upstream/borgbackup
1
0
Fork 0
mirror of https://github.com/borgbackup/borg.git synced 2026-06-09 00:32:37 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions 5

Merge branch 'master' into multithreading

Browse source
This commit is contained in:
Thomas Waldmann 2015-06-27 22:24:51 +02:00
commit 4736f5b9d0
24 changed files with 915 additions and 340 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
AUTHORS
View file

@ -1,6 +1,7 @@
Borg Developers / Contributors ("The Borg Collective")
``````````````````````````````````````````````````````
- Thomas Waldmann
- Thomas Waldmann <tw@waldmann-edv.de>
- Antoine Beaupré
Borg is a fork of Attic. Attic is written and maintained

127
CHANGES
View file

@ -1,56 +1,108 @@
Borg Changelog
==============
Version <TBD>
-------------
Version 0.24.0
--------------
New features:
- borg create --chunker-params ... to configure the chunker.
See docs/misc/create_chunker-params.txt for more information.
- borg info now reports chunk counts in the chunk index.
Bug fixes:
- reduce memory usage, see --chunker-params, fixes #16.
This can be used to reduce chunk management overhead, so borg does not create
a huge chunks index/repo index and eats all your RAM if you back up lots of
data in huge files (like VM disk images).
- better Exception msg if there is no Borg installed on the remote repo server.
Other changes:
- Fedora/Fedora-based install instructions added to docs.
- added docs/misc directory for misc. writeups that won't be included "as is"
into the html docs.
I forgot to list some stuff already implemented in 0.23.0, here they are:
New features:
- efficient archive list from manifest, meaning a big speedup for slow
repo connections and "list <repo>", "delete <repo>", "prune"
- big speedup for chunks cache sync (esp. for slow repo connections), fixes #18
- hashindex: improve error messages
Other changes:
- explicitly specify binary mode to open binary files
- some easy micro optimizations
Version 0.23.0
--------------
Incompatible changes (compared to attic, fork related):
- changed sw name and cli command to "borg", updated docs
- package name and name in urls uses "borgbackup" to have less collisions
- package name (and name in urls) uses "borgbackup" to have less collisions
- changed repo / cache internal magic strings from ATTIC* to BORG*,
changed cache location to .cache/borg/
- give specific path to xattr.is_enabled(), disable symlink setattr call that
always fails
- fix misleading hint the fuse ImportError handler gave, fixes attic #237
- source: misc. cleanups, pep8, style
- implement check --last N
- check: sort archives in reverse time order
changed cache location to .cache/borg/ - this means that it currently won't
accept attic repos (see issue #21 about improving that)
Bug fixes:
- avoid defect python-msgpack releases, fixes attic #171, fixes attic #185
- check unpacked data from RPC for tuple type and correct length, fixes attic #127
- less memory usage: add global option --no-cache-files
- fix traceback when trying to do unsupported passphrase change, fixes attic #189
- datetime does not like the year 10.000, fixes attic #139
- docs and faq improvements, fixes, updates
- cleanup crypto.pyx, make it easier to adapt to other modes
- extract: if --stdout is given, write all extracted binary data to stdout
- fix "info" all archives stats, fixes attic #183
- fix parsing with missing microseconds, fixes attic #282
- fix misleading hint the fuse ImportError handler gave, fixes attic #237
- check unpacked data from RPC for tuple type and correct length, fixes attic #127
- fix Repository._active_txn state when lock upgrade fails
- give specific path to xattr.is_enabled(), disable symlink setattr call that
always fails
- fix test setup for 32bit platforms, partial fix for attic #196
- upgraded versioneer, PEP440 compliance, fixes attic #257
New features:
- less memory usage: add global option --no-cache-files
- check --last N (only check the last N archives)
- check: sort archives in reverse time order
- rename repo::oldname newname (rename repository)
- create -v output more informative
- create --progress (backup progress indicator)
- create --timestamp (utc string or reference file/dir)
- create: if "-" is given as path, read binary from stdin
- do os.fsync like recommended in the python docs
- extract: if --stdout is given, write all extracted binary data to stdout
- extract --sparse (simple sparse file support)
- extra debug information for 'fread failed'
- delete <repo> (deletes whole repo + local cache)
- FUSE: reflect deduplication in allocated blocks
- only allow whitelisted RPC calls in server mode
- normalize source/exclude paths before matching
- fix "info" all archives stats, fixes attic #183
- implement create --timestamp, utc string or reference file/dir
- simple sparse file support (extract --sparse)
- fix parsing with missing microseconds, fixes attic #282
- use posix_fadvise to not spoil the OS cache, fixes attic #252
- source: Let chunker optionally work with os-level file descriptor.
- source: Linux: remove duplicate os.fsencode calls
- fix test setup for 32bit platforms, partial fix for attic #196
- source: refactor _open_rb code a bit, so it is more consistent / regular
- implement rename repo::oldname newname
- implement create --progress
- source: refactor indicator (status) and item processing
- implement delete repo (also deletes local cache)
- better create -v output
- upgraded versioneer, PEP440 compliance, fixes attic #257
- source: use py.test for better testing, flake8 for code style checks
- source: fix tox >=2.0 compatibility
- toplevel error handler: show tracebacks for better error analysis
- sigusr1 / sigint handler to print current file infos - attic PR #286
- pypi package: add python version classifiers, add FreeBSD to platforms
- fix Repository._active_txn state when lock upgrade fails
- RPCError: include the exception args we get from remote
Other changes:
- source: misc. cleanups, pep8, style
- docs and faq improvements, fixes, updates
- cleanup crypto.pyx, make it easier to adapt to other AES modes
- do os.fsync like recommended in the python docs
- source: Let chunker optionally work with os-level file descriptor.
- source: Linux: remove duplicate os.fsencode calls
- source: refactor _open_rb code a bit, so it is more consistent / regular
- source: refactor indicator (status) and item processing
- source: use py.test for better testing, flake8 for code style checks
- source: fix tox >=2.0 compatibility (test runner)
- pypi package: add python version classifiers, add FreeBSD to platforms
Attic Changelog
===============
@ -58,6 +110,13 @@ Attic Changelog
Here you can see the full list of changes between each Attic release until Borg
forked from Attic:
Version 0.17
------------
(bugfix release, released on X)
- Fix hashindex ARM memory alignment issue (#309)
- Improve hashindex error messages (#298)
Version 0.16
------------

2
MANIFEST.in
View file

@ -1,4 +1,4 @@
include README.rst LICENSE CHANGES MANIFEST.in versioneer.py
include README.rst AUTHORS LICENSE CHANGES MANIFEST.in versioneer.py
recursive-include borg *.pyx
recursive-include docs *
recursive-exclude docs *.pyc

10
README.rst
View file

@ -10,8 +10,12 @@ are stored.
Borg is a fork of Attic and maintained by "The Borg Collective" (see AUTHORS file).
BORG IS NOT COMPATIBLE WITH ORIGINAL ATTIC.
UNTIL FURTHER NOTICE, EXPECT THAT WE WILL BREAK COMPATIBILITY REPEATEDLY.
THIS IS SOFTWARE IN DEVELOPMENT, DECIDE YOURSELF IF IT FITS YOUR NEEDS.
EXPECT THAT WE WILL BREAK COMPATIBILITY REPEATEDLY WHEN MAJOR RELEASE NUMBER
CHANGES (like when going from 0.x.y to 1.0.0). Please read CHANGES document.
NOT RELEASED DEVELOPMENT VERSIONS HAVE UNKNOWN COMPATIBILITY PROPERTIES.
THIS IS SOFTWARE IN DEVELOPMENT, DECIDE YOURSELF WHETHER IT FITS YOUR NEEDS.
Read issue #1 on the issue tracker, goals are being defined there.
@ -66,7 +70,7 @@ Where are the tests?
The tests are in the borg/testsuite package. To run the test suite use the
following command::
$ fakeroot -u tox # you need to have tox installed
$ fakeroot -u tox # you need to have tox and pytest installed
.. |build| image:: https://travis-ci.org/borgbackup/borg.svg
:alt: Build Status

7
borg/_chunker.c
View file

@ -79,7 +79,7 @@ typedef struct {
int window_size, chunk_mask, min_size;
size_t buf_size;
uint32_t *table;
uint8_t *data, *read_buf;
uint8_t *data;
PyObject *fd;
int fh;
int done, eof;
@ -96,7 +96,6 @@ chunker_init(int window_size, int chunk_mask, int min_size, int max_size, uint32
c->table = buzhash_init_table(seed);
c->buf_size = max_size;
c->data = malloc(c->buf_size);
c->read_buf = malloc(c->buf_size);
return c;
}
@ -122,7 +121,6 @@ chunker_free(Chunker *c)
Py_XDECREF(c->fd);
free(c->table);
free(c->data);
free(c->read_buf);
free(c);
}
@ -140,9 +138,8 @@ chunker_fill(Chunker *c)
}
if(c->fh >= 0) {
// if we have a os-level file descriptor, use os-level API
n = read(c->fh, c->read_buf, n);
n = read(c->fh, c->data + c->position + c->remaining, n);
if(n > 0) {
memcpy(c->data + c->position + c->remaining, c->read_buf, n);
c->remaining += n;
c->bytes_read += n;
}

118
borg/_hashindex.c
View file

@ -18,8 +18,11 @@
#error Unknown byte order
#endif
#define MAGIC "BORG_IDX"
#define MAGIC_LEN 8
typedef struct {
char magic[8];
char magic[MAGIC_LEN];
int32_t num_entries;
int32_t num_buckets;
int8_t key_size;
@ -27,7 +30,6 @@ typedef struct {
} __attribute__((__packed__)) HashHeader;
typedef struct {
void *data;
void *buckets;
int num_entries;
int num_buckets;
@ -36,10 +38,8 @@ typedef struct {
off_t bucket_size;
int lower_limit;
int upper_limit;
off_t data_len;
} HashIndex;
#define MAGIC "BORG_IDX"
#define EMPTY _htole32(0xffffffff)
#define DELETED _htole32(0xfffffffe)
#define MAX_BUCKET_SIZE 512
@ -57,8 +57,10 @@ typedef struct {
#define BUCKET_MARK_DELETED(index, idx) (*((uint32_t *)(BUCKET_ADDR(index, idx) + index->key_size)) = DELETED)
#define BUCKET_MARK_EMPTY(index, idx) (*((uint32_t *)(BUCKET_ADDR(index, idx) + index->key_size)) = EMPTY)
#define EPRINTF(msg, ...) fprintf(stderr, "hashindex: " msg "\n", ##__VA_ARGS__)
#define EPRINTF_PATH(path, msg, ...) fprintf(stderr, "hashindex: %s: " msg "\n", path, ##__VA_ARGS__)
#define EPRINTF_MSG(msg, ...) fprintf(stderr, "hashindex: " msg "\n", ##__VA_ARGS__)
#define EPRINTF_MSG_PATH(path, msg, ...) fprintf(stderr, "hashindex: %s: " msg "\n", path, ##__VA_ARGS__)
#define EPRINTF(msg, ...) fprintf(stderr, "hashindex: " msg "(%s)\n", ##__VA_ARGS__, strerror(errno))
#define EPRINTF_PATH(path, msg, ...) fprintf(stderr, "hashindex: %s: " msg " (%s)\n", path, ##__VA_ARGS__, strerror(errno))
static HashIndex *hashindex_read(const char *path);
static int hashindex_write(HashIndex *index, const char *path);
@ -118,13 +120,11 @@ hashindex_resize(HashIndex *index, int capacity)
while((key = hashindex_next_key(index, key))) {
hashindex_set(new, key, hashindex_get(index, key));
}
free(index->data);
index->data = new->data;
index->data_len = new->data_len;
free(index->buckets);
index->buckets = new->buckets;
index->num_buckets = new->num_buckets;
index->lower_limit = new->lower_limit;
index->upper_limit = new->upper_limit;
index->buckets = new->buckets;
free(new);
return 1;
}
@ -134,18 +134,22 @@ static HashIndex *
hashindex_read(const char *path)
{
FILE *fd;
off_t length;
off_t bytes_read;
off_t length, buckets_length, bytes_read;
HashHeader header;
HashIndex *index = NULL;
if((fd = fopen(path, "r")) == NULL) {
EPRINTF_PATH(path, "fopen failed");
if((fd = fopen(path, "rb")) == NULL) {
EPRINTF_PATH(path, "fopen for reading failed");
return NULL;
}
bytes_read = fread(&header, 1, sizeof(HashHeader), fd);
if(bytes_read != sizeof(HashHeader)) {
EPRINTF_PATH(path, "fread header failed (expected %ld, got %ld)", sizeof(HashHeader), bytes_read);
if(ferror(fd)) {
EPRINTF_PATH(path, "fread header failed (expected %ld, got %ld)", sizeof(HashHeader), bytes_read);
}
else {
EPRINTF_MSG_PATH(path, "fread header failed (expected %ld, got %ld)", sizeof(HashHeader), bytes_read);
}
goto fail;
}
if(fseek(fd, 0, SEEK_END) < 0) {
@ -156,43 +160,47 @@ hashindex_read(const char *path)
EPRINTF_PATH(path, "ftell failed");
goto fail;
}
if(fseek(fd, 0, SEEK_SET) < 0) {
if(fseek(fd, sizeof(HashHeader), SEEK_SET) < 0) {
EPRINTF_PATH(path, "fseek failed");
goto fail;
}
if(memcmp(header.magic, MAGIC, 8)) {
EPRINTF_PATH(path, "Unknown file header");
if(memcmp(header.magic, MAGIC, MAGIC_LEN)) {
EPRINTF_MSG_PATH(path, "Unknown MAGIC in header");
goto fail;
}
if(length != sizeof(HashHeader) + (off_t)_le32toh(header.num_buckets) * (header.key_size + header.value_size)) {
EPRINTF_PATH(path, "Incorrect file length");
buckets_length = (off_t)_le32toh(header.num_buckets) * (header.key_size + header.value_size);
if(length != sizeof(HashHeader) + buckets_length) {
EPRINTF_MSG_PATH(path, "Incorrect file length (expected %ld, got %ld)", sizeof(HashHeader) + buckets_length, length);
goto fail;
}
if(!(index = malloc(sizeof(HashIndex)))) {
EPRINTF_PATH(path, "malloc failed");
EPRINTF_PATH(path, "malloc header failed");
goto fail;
}
if(!(index->data = malloc(length))) {
EPRINTF_PATH(path, "malloc failed");
if(!(index->buckets = malloc(buckets_length))) {
EPRINTF_PATH(path, "malloc buckets failed");
free(index);
index = NULL;
goto fail;
}
bytes_read = fread(index->data, 1, length, fd);
if(bytes_read != length) {
EPRINTF_PATH(path, "fread hashindex failed (expected %ld, got %ld)", length, bytes_read);
free(index->data);
bytes_read = fread(index->buckets, 1, buckets_length, fd);
if(bytes_read != buckets_length) {
if(ferror(fd)) {
EPRINTF_PATH(path, "fread buckets failed (expected %ld, got %ld)", buckets_length, bytes_read);
}
else {
EPRINTF_MSG_PATH(path, "fread buckets failed (expected %ld, got %ld)", buckets_length, bytes_read);
}
free(index->buckets);
free(index);
index = NULL;
goto fail;
}
index->data_len = length;
index->num_entries = _le32toh(header.num_entries);
index->num_buckets = _le32toh(header.num_buckets);
index->key_size = header.key_size;
index->value_size = header.value_size;
index->bucket_size = index->key_size + index->value_size;
index->buckets = index->data + sizeof(HashHeader);
index->lower_limit = index->num_buckets > MIN_BUCKETS ? ((int)(index->num_buckets * BUCKET_LOWER_LIMIT)) : 0;
index->upper_limit = (int)(index->num_buckets * BUCKET_UPPER_LIMIT);
fail:
@ -205,20 +213,18 @@ fail:
static HashIndex *
hashindex_init(int capacity, int key_size, int value_size)
{
off_t buckets_length;
HashIndex *index;
HashHeader header = {
.magic = MAGIC, .num_entries = 0, .key_size = key_size, .value_size = value_size
};
int i;
capacity = MAX(MIN_BUCKETS, capacity);
if(!(index = malloc(sizeof(HashIndex)))) {
EPRINTF("malloc failed");
EPRINTF("malloc header failed");
return NULL;
}
index->data_len = sizeof(HashHeader) + (off_t)capacity * (key_size + value_size);
if(!(index->data = calloc(index->data_len, 1))) {
EPRINTF("malloc failed");
buckets_length = (off_t)capacity * (key_size + value_size);
if(!(index->buckets = calloc(buckets_length, 1))) {
EPRINTF("malloc buckets failed");
free(index);
return NULL;
}
@ -229,8 +235,6 @@ hashindex_init(int capacity, int key_size, int value_size)
index->bucket_size = index->key_size + index->value_size;
index->lower_limit = index->num_buckets > MIN_BUCKETS ? ((int)(index->num_buckets * BUCKET_LOWER_LIMIT)) : 0;
index->upper_limit = (int)(index->num_buckets * BUCKET_UPPER_LIMIT);
index->buckets = index->data + sizeof(HashHeader);
memcpy(index->data, &header, sizeof(HashHeader));
for(i = 0; i < capacity; i++) {
BUCKET_MARK_EMPTY(index, i);
}
@ -240,25 +244,34 @@ hashindex_init(int capacity, int key_size, int value_size)
static void
hashindex_free(HashIndex *index)
{
free(index->data);
free(index->buckets);
free(index);
}
static int
hashindex_write(HashIndex *index, const char *path)
{
off_t buckets_length = (off_t)index->num_buckets * index->bucket_size;
FILE *fd;
HashHeader header = {
.magic = MAGIC,
.num_entries = _htole32(index->num_entries),
.num_buckets = _htole32(index->num_buckets),
.key_size = index->key_size,
.value_size = index->value_size
};
int ret = 1;
if((fd = fopen(path, "w")) == NULL) {
EPRINTF_PATH(path, "open failed");
fprintf(stderr, "Failed to open %s for writing\n", path);
if((fd = fopen(path, "wb")) == NULL) {
EPRINTF_PATH(path, "fopen for writing failed");
return 0;
}
*((uint32_t *)(index->data + 8)) = _htole32(index->num_entries);
*((uint32_t *)(index->data + 12)) = _htole32(index->num_buckets);
if(fwrite(index->data, 1, index->data_len, fd) != index->data_len) {
EPRINTF_PATH(path, "fwrite failed");
if(fwrite(&header, 1, sizeof(header), fd) != sizeof(header)) {
EPRINTF_PATH(path, "fwrite header failed");
ret = 0;
}
if(fwrite(index->buckets, 1, buckets_length, fd) != buckets_length) {
EPRINTF_PATH(path, "fwrite buckets failed");
ret = 0;
}
if(fclose(fd) < 0) {
@ -348,14 +361,18 @@ hashindex_get_size(HashIndex *index)
}
static void
hashindex_summarize(HashIndex *index, long long *total_size, long long *total_csize, long long *total_unique_size, long long *total_unique_csize)
hashindex_summarize(HashIndex *index, long long *total_size, long long *total_csize,
long long *total_unique_size, long long *total_unique_csize,
long long *total_unique_chunks, long long *total_chunks)
{
int64_t size = 0, csize = 0, unique_size = 0, unique_csize = 0;
int64_t size = 0, csize = 0, unique_size = 0, unique_csize = 0, chunks = 0, unique_chunks = 0;
const int32_t *values;
void *key = NULL;
while((key = hashindex_next_key(index, key))) {
values = key + 32;
values = key + index->key_size;
unique_chunks++;
chunks += values[0];
unique_size += values[1];
unique_csize += values[2];
size += values[0] * values[1];
@ -365,5 +382,6 @@ hashindex_summarize(HashIndex *index, long long *total_size, long long *total_cs
*total_csize = csize;
*total_unique_size = unique_size;
*total_unique_csize = unique_csize;
*total_unique_chunks = unique_chunks;
*total_chunks = chunks;
}

53
borg/archive.py
View file

@ -24,12 +24,14 @@ from .helpers import parse_timestamp, Error, uid2user, user2uid, gid2group, grou
make_queue, TerminatedQueue
ITEMS_BUFFER = 1024 * 1024
CHUNK_MIN = 1024
CHUNK_MAX = 10 * 1024 * 1024
WINDOW_SIZE = 0xfff
CHUNK_MASK = 0xffff
ZEROS = b'\0' * CHUNK_MAX
CHUNK_MIN_EXP = 10 # 2**10 == 1kiB
CHUNK_MAX_EXP = 23 # 2**23 == 8MiB
HASH_WINDOW_SIZE = 0xfff # 4095B
HASH_MASK_BITS = 16 # results in ~64kiB chunks statistically
# defaults, use --chunker-params to override
CHUNKER_PARAMS = (CHUNK_MIN_EXP, CHUNK_MAX_EXP, HASH_MASK_BITS, HASH_WINDOW_SIZE)
utime_supports_fd = os.utime in getattr(os, 'supports_fd', {})
utime_supports_follow_symlinks = os.utime in getattr(os, 'supports_follow_symlinks', {})
@ -72,12 +74,12 @@ class DownloadPipeline:
class ChunkBuffer:
BUFFER_SIZE = 1 * 1024 * 1024
def __init__(self, key):
def __init__(self, key, chunker_params=CHUNKER_PARAMS):
self.buffer = BytesIO()
self.packer = msgpack.Packer(unicode_errors='surrogateescape')
self.chunks = []
self.key = key
self.chunker = Chunker(WINDOW_SIZE, CHUNK_MASK, CHUNK_MIN, CHUNK_MAX,self.key.chunk_seed)
self.chunker = Chunker(self.key.chunk_seed, *chunker_params)
def add(self, item):
self.buffer.write(self.packer.pack(StableDict(item)))
@ -107,8 +109,8 @@ class ChunkBuffer:
class CacheChunkBuffer(ChunkBuffer):
def __init__(self, cache, key, stats):
super(CacheChunkBuffer, self).__init__(key)
def __init__(self, cache, key, stats, chunker_params=CHUNKER_PARAMS):
super(CacheChunkBuffer, self).__init__(key, chunker_params)
self.cache = cache
self.stats = stats
@ -317,7 +319,8 @@ class Archive:
def __init__(self, repository, key, manifest, name, cache=None, create=False,
checkpoint_interval=300, numeric_owner=False, progress=False):
checkpoint_interval=300, numeric_owner=False, progress=False,
chunker_params=CHUNKER_PARAMS):
self.cwd = os.getcwd()
self.key = key
self.repository = repository
@ -333,8 +336,8 @@ class Archive:
self.pipeline = DownloadPipeline(self.repository, self.key)
if create:
self.pp = ParallelProcessor(self)
self.items_buffer = CacheChunkBuffer(self.cache, self.key, self.stats)
self.chunker = Chunker(WINDOW_SIZE, CHUNK_MASK, CHUNK_MIN, CHUNK_MAX, self.key.chunk_seed)
self.items_buffer = CacheChunkBuffer(self.cache, self.key, self.stats, chunker_params)
self.chunker = Chunker(self.key.chunk_seed, *chunker_params)
if name in manifest.archives:
raise self.AlreadyExists(name)
self.last_checkpoint = time.time()
@ -350,6 +353,7 @@ class Archive:
raise self.DoesNotExist(name)
info = self.manifest.archives[name]
self.load(info[b'id'])
self.zeros = b'\0' * (1 << chunker_params[1])
def close(self):
if self.pp:
@ -475,12 +479,7 @@ class Archive:
except OSError:
pass
mode = item[b'mode']
if stat.S_ISDIR(mode):
if not os.path.exists(path):
os.makedirs(path)
if restore_attrs:
self.restore_attrs(path, item)
elif stat.S_ISREG(mode):
if stat.S_ISREG(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
# Hard link?
@ -501,7 +500,7 @@ class Archive:
with open(path, 'wb') as fd:
ids = [c[0] for c in item[b'chunks']]
for data in self.pipeline.fetch_many(ids, is_preloaded=True):
if sparse and ZEROS.startswith(data):
if sparse and self.zeros.startswith(data):
# all-zero chunk: create a hole in a sparse file
fd.seek(len(data), 1)
else:
@ -510,11 +509,11 @@ class Archive:
fd.truncate(pos)
fd.flush()
self.restore_attrs(path, item, fd=fd.fileno())
elif stat.S_ISFIFO(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
os.mkfifo(path)
self.restore_attrs(path, item)
elif stat.S_ISDIR(mode):
if not os.path.exists(path):
os.makedirs(path)
if restore_attrs:
self.restore_attrs(path, item)
elif stat.S_ISLNK(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
@ -523,6 +522,11 @@ class Archive:
os.unlink(path)
os.symlink(source, path)
self.restore_attrs(path, item, symlink=True)
elif stat.S_ISFIFO(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
os.mkfifo(path)
self.restore_attrs(path, item)
elif stat.S_ISCHR(mode) or stat.S_ISBLK(mode):
os.mknod(path, item[b'mode'], item[b'rdev'])
self.restore_attrs(path, item)
@ -700,6 +704,7 @@ class Archive:
@staticmethod
def list_archives(repository, key, manifest, cache=None):
# expensive! see also Manifest.list_archive_infos.
for name, info in manifest.archives.items():
yield Archive(repository, key, manifest, name, cache=cache)

61
borg/archiver.py
View file

@ -13,7 +13,7 @@ import textwrap
import traceback
from . import __version__
from .archive import Archive, ArchiveChecker
from .archive import Archive, ArchiveChecker, CHUNKER_PARAMS
from .repository import Repository
from .cache import Cache
from .key import key_creator
@ -21,7 +21,7 @@ from .helpers import Error, location_validator, format_time, format_file_size, \
format_file_mode, ExcludePattern, exclude_path, adjust_patterns, to_localtime, timestamp, \
get_cache_dir, get_keys_dir, format_timedelta, prune_within, prune_split, \
Manifest, remove_surrogates, update_excludes, format_archive, check_extension_modules, Statistics, \
is_cachedir, bigint_to_int
is_cachedir, bigint_to_int, ChunkerParams
from .remote import RepositoryServer, RemoteRepository
@ -101,10 +101,12 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
t0 = datetime.now()
repository = self.open_repository(args.archive, exclusive=True)
manifest, key = Manifest.load(repository)
key.compression_level = args.compression
cache = Cache(repository, key, manifest, do_files=args.cache_files)
archive = Archive(repository, key, manifest, args.archive.archive, cache=cache,
create=True, checkpoint_interval=args.checkpoint_interval,
numeric_owner=args.numeric_owner, progress=args.progress)
numeric_owner=args.numeric_owner, progress=args.progress,
chunker_params=args.chunker_params)
try:
# Add cache dir to inode_skip list
skip_inodes = set()
@ -171,9 +173,6 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
# Entering a new filesystem?
if restrict_dev and st.st_dev != restrict_dev:
return
# Ignore unix sockets
if stat.S_ISSOCK(st.st_mode):
return
status = None
if stat.S_ISREG(st.st_mode):
try:
@ -199,6 +198,9 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
status = archive.process_fifo(path, st)
elif stat.S_ISCHR(st.st_mode) or stat.S_ISBLK(st.st_mode):
status = archive.process_dev(path, st)
elif stat.S_ISSOCK(st.st_mode):
# Ignore unix sockets
return
else:
self.print_error('Unknown file type: %s', path)
return
@ -287,8 +289,8 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
stats.print_('Deleted data:', cache)
else:
print("You requested to completely DELETE the repository *including* all archives it contains:")
for archive in sorted(Archive.list_archives(repository, key, manifest), key=attrgetter('ts')):
print(format_archive(archive))
for archive_info in manifest.list_archive_infos(sort_by='ts'):
print(format_archive(archive_info))
print("""Type "YES" if you understand this and want to continue.\n""")
if input('Do you want to continue? ') == 'YES':
repository.destroy()
@ -357,8 +359,8 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
item[b'group'] or item[b'gid'], size, format_time(mtime),
remove_surrogates(item[b'path']), extra))
else:
for archive in sorted(Archive.list_archives(repository, key, manifest), key=attrgetter('ts')):
print(format_archive(archive))
for archive_info in manifest.list_archive_infos(sort_by='ts'):
print(format_archive(archive_info))
return self.exit_code
def do_info(self, args):
@ -383,11 +385,10 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
repository = self.open_repository(args.repository, exclusive=True)
manifest, key = Manifest.load(repository)
cache = Cache(repository, key, manifest, do_files=args.cache_files)
archives = list(sorted(Archive.list_archives(repository, key, manifest, cache),
key=attrgetter('ts'), reverse=True))
archives = manifest.list_archive_infos(sort_by='ts', reverse=True) # just a ArchiveInfo list
if args.hourly + args.daily + args.weekly + args.monthly + args.yearly == 0 and args.within is None:
self.print_error('At least one of the "within", "hourly", "daily", "weekly", "monthly" or "yearly" '
'settings must be specified')
self.print_error('At least one of the "within", "keep-hourly", "keep-daily", "keep-weekly", '
'"keep-monthly" or "keep-yearly" settings must be specified')
return 1
if args.prefix:
archives = [archive for archive in archives if archive.name.startswith(args.prefix)]
@ -415,7 +416,7 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
self.print_verbose('Would prune: %s' % format_archive(archive))
else:
self.print_verbose('Pruning archive: %s' % format_archive(archive))
archive.delete(stats)
Archive(repository, key, manifest, archive.name, cache).delete(stats)
if to_delete and not args.dry_run:
manifest.write()
repository.commit()
@ -519,8 +520,12 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
parser = argparse.ArgumentParser(description='Borg %s - Deduplicated Backups' % __version__)
subparsers = parser.add_subparsers(title='Available commands')
serve_epilog = textwrap.dedent("""
This command starts a repository server process. This command is usually not used manually.
""")
subparser = subparsers.add_parser('serve', parents=[common_parser],
description=self.do_serve.__doc__)
description=self.do_serve.__doc__, epilog=serve_epilog,
formatter_class=argparse.RawDescriptionHelpFormatter)
subparser.set_defaults(func=self.do_serve)
subparser.add_argument('--restrict-to-path', dest='restrict_to_paths', action='append',
metavar='PATH', help='restrict repository access to PATH')
@ -625,6 +630,14 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
metavar='yyyy-mm-ddThh:mm:ss',
help='manually specify the archive creation date/time (UTC). '
'alternatively, give a reference file/directory.')
subparser.add_argument('--chunker-params', dest='chunker_params',
type=ChunkerParams, default=CHUNKER_PARAMS,
metavar='CHUNK_MIN_EXP,CHUNK_MAX_EXP,HASH_MASK_BITS,HASH_WINDOW_SIZE',
help='specify the chunker parameters. default: %d,%d,%d,%d' % CHUNKER_PARAMS)
subparser.add_argument('-C', '--compression', dest='compression',
type=int, default=0, metavar='N',
help='select compression algorithm and level. 0..9 is supported and means zlib '
'level 0 (no compression, fast, default) .. zlib level 9 (high compression, slow).')
subparser.add_argument('archive', metavar='ARCHIVE',
type=location_validator(archive=True),
help='archive to create')
@ -856,19 +869,19 @@ def main():
try:
exit_code = archiver.run(sys.argv[1:])
except Error as e:
traceback.print_exc()
archiver.print_error(e.get_message())
archiver.print_error(e.get_message() + "\n%s" % traceback.format_exc())
exit_code = e.exit_code
except RemoteRepository.RPCError as e:
print(e)
archiver.print_error('Error: Remote Exception.\n%s' % str(e))
exit_code = 1
except Exception:
archiver.print_error('Error: Local Exception.\n%s' % traceback.format_exc())
exit_code = 1
except KeyboardInterrupt:
traceback.print_exc()
archiver.print_error('Error: Keyboard interrupt')
archiver.print_error('Error: Keyboard interrupt.\n%s' % traceback.format_exc())
exit_code = 1
else:
if exit_code:
archiver.print_error('Exiting with failure status due to previous errors')
if exit_code:
archiver.print_error('Exiting with failure status due to previous errors')
sys.exit(exit_code)
if __name__ == '__main__':

149
borg/cache.py
View file

@ -1,11 +1,14 @@
from configparser import RawConfigParser
from .remote import cache_if_remote
import errno
import msgpack
import os
import sys
import threading
from binascii import hexlify
import shutil
import tarfile
import tempfile
from .key import PlaintextKey
from .helpers import Error, get_cache_dir, decode_dict, st_mtime_ns, unhexlify, UpgradableLock, int_to_bigint, \
@ -98,7 +101,9 @@ class Cache:
with open(os.path.join(self.path, 'config'), 'w') as fd:
config.write(fd)
ChunkIndex().write(os.path.join(self.path, 'chunks').encode('utf-8'))
with open(os.path.join(self.path, 'files'), 'w') as fd:
with open(os.path.join(self.path, 'chunks.archive'), 'wb') as fd:
pass # empty file
with open(os.path.join(self.path, 'files'), 'wb') as fd:
pass # empty file
def destroy(self):
@ -153,6 +158,7 @@ class Cache:
os.mkdir(txn_dir)
shutil.copy(os.path.join(self.path, 'config'), txn_dir)
shutil.copy(os.path.join(self.path, 'chunks'), txn_dir)
shutil.copy(os.path.join(self.path, 'chunks.archive'), txn_dir)
shutil.copy(os.path.join(self.path, 'files'), txn_dir)
os.rename(os.path.join(self.path, 'txn.tmp'),
os.path.join(self.path, 'txn.active'))
@ -194,6 +200,7 @@ class Cache:
if os.path.exists(txn_dir):
shutil.copy(os.path.join(txn_dir, 'config'), self.path)
shutil.copy(os.path.join(txn_dir, 'chunks'), self.path)
shutil.copy(os.path.join(txn_dir, 'chunks.archive'), self.path)
shutil.copy(os.path.join(txn_dir, 'files'), self.path)
os.rename(txn_dir, os.path.join(self.path, 'txn.tmp'))
if os.path.exists(os.path.join(self.path, 'txn.tmp')):
@ -202,37 +209,139 @@ class Cache:
self._do_open()
def sync(self):
"""Initializes cache by fetching and reading all archive indicies
"""Re-synchronize chunks cache with repository.
If present, uses a compressed tar archive of known backup archive
indices, so it only needs to fetch infos from repo and build a chunk
index once per backup archive.
If out of sync, the tar gets rebuilt from known + fetched chunk infos,
so it has complete and current information about all backup archives.
Finally, it builds the master chunks index by merging all indices from
the tar.
Note: compression (esp. xz) is very effective in keeping the tar
relatively small compared to the files it contains.
"""
def add(id, size, csize):
in_archive_path = os.path.join(self.path, 'chunks.archive')
out_archive_path = os.path.join(self.path, 'chunks.archive.tmp')
def open_in_archive():
try:
count, size, csize = self.chunks[id]
self.chunks[id] = count + 1, size, csize
tf = tarfile.open(in_archive_path, 'r')
except OSError as e:
if e.errno != errno.ENOENT:
raise
# file not found
tf = None
except tarfile.ReadError:
# empty file?
tf = None
return tf
def open_out_archive():
for compression in ('xz', 'bz2', 'gz'):
# xz needs py 3.3, bz2 and gz also work on 3.2
try:
tf = tarfile.open(out_archive_path, 'w:'+compression, format=tarfile.PAX_FORMAT)
break
except tarfile.CompressionError:
continue
else: # shouldn't happen
tf = None
return tf
def close_archive(tf):
if tf:
tf.close()
def delete_in_archive():
os.unlink(in_archive_path)
def rename_out_archive():
os.rename(out_archive_path, in_archive_path)
def add(chunk_idx, id, size, csize, incr=1):
try:
count, size, csize = chunk_idx[id]
chunk_idx[id] = count + incr, size, csize
except KeyError:
self.chunks[id] = 1, size, csize
self.begin_txn()
print('Initializing cache...')
self.chunks.clear()
unpacker = msgpack.Unpacker()
repository = cache_if_remote(self.repository)
for name, info in self.manifest.archives.items():
archive_id = info[b'id']
chunk_idx[id] = incr, size, csize
def transfer_known_idx(archive_id, tf_in, tf_out):
archive_id_hex = hexlify(archive_id).decode('ascii')
tarinfo = tf_in.getmember(archive_id_hex)
archive_name = tarinfo.pax_headers['archive_name']
print('Already known archive:', archive_name)
f_in = tf_in.extractfile(archive_id_hex)
tf_out.addfile(tarinfo, f_in)
return archive_name
def fetch_and_build_idx(archive_id, repository, key, tmp_dir, tf_out):
chunk_idx = ChunkIndex()
cdata = repository.get(archive_id)
data = self.key.decrypt(archive_id, cdata)
add(archive_id, len(data), len(cdata))
data = key.decrypt(archive_id, cdata)
add(chunk_idx, archive_id, len(data), len(cdata))
archive = msgpack.unpackb(data)
if archive[b'version'] != 1:
raise Exception('Unknown archive metadata version')
decode_dict(archive, (b'name',))
print('Analyzing archive:', archive[b'name'])
for key, chunk in zip(archive[b'items'], repository.get_many(archive[b'items'])):
data = self.key.decrypt(key, chunk)
add(key, len(data), len(chunk))
print('Analyzing new archive:', archive[b'name'])
unpacker = msgpack.Unpacker()
for item_id, chunk in zip(archive[b'items'], repository.get_many(archive[b'items'])):
data = key.decrypt(item_id, chunk)
add(chunk_idx, item_id, len(data), len(chunk))
unpacker.feed(data)
for item in unpacker:
if b'chunks' in item:
for chunk_id, size, csize in item[b'chunks']:
add(chunk_id, size, csize)
add(chunk_idx, chunk_id, size, csize)
archive_id_hex = hexlify(archive_id).decode('ascii')
file_tmp = os.path.join(tmp_dir, archive_id_hex).encode('utf-8')
chunk_idx.write(file_tmp)
tarinfo = tf_out.gettarinfo(file_tmp, archive_id_hex)
tarinfo.pax_headers['archive_name'] = archive[b'name']
with open(file_tmp, 'rb') as f:
tf_out.addfile(tarinfo, f)
os.unlink(file_tmp)
def create_master_idx(chunk_idx, tf_in, tmp_dir):
chunk_idx.clear()
for tarinfo in tf_in:
archive_id_hex = tarinfo.name
tf_in.extract(archive_id_hex, tmp_dir)
chunk_idx_path = os.path.join(tmp_dir, archive_id_hex).encode('utf-8')
archive_chunk_idx = ChunkIndex.read(chunk_idx_path)
for chunk_id, (count, size, csize) in archive_chunk_idx.iteritems():
add(chunk_idx, chunk_id, size, csize, incr=count)
os.unlink(chunk_idx_path)
self.begin_txn()
print('Synchronizing chunks cache...')
# XXX we have to do stuff on disk due to lacking ChunkIndex api
with tempfile.TemporaryDirectory() as tmp_dir:
repository = cache_if_remote(self.repository)
out_archive = open_out_archive()
in_archive = open_in_archive()
if in_archive:
known_ids = set(unhexlify(hexid) for hexid in in_archive.getnames())
else:
known_ids = set()
archive_ids = set(info[b'id'] for info in self.manifest.archives.values())
print('Rebuilding archive collection. Known: %d Repo: %d Unknown: %d' % (
len(known_ids), len(archive_ids), len(archive_ids - known_ids), ))
for archive_id in archive_ids & known_ids:
transfer_known_idx(archive_id, in_archive, out_archive)
close_archive(in_archive)
delete_in_archive() # free disk space
for archive_id in archive_ids - known_ids:
fetch_and_build_idx(archive_id, repository, self.key, tmp_dir, out_archive)
close_archive(out_archive)
rename_out_archive()
print('Merging collection into master chunks cache...')
in_archive = open_in_archive()
create_master_idx(self.chunks, in_archive, tmp_dir)
close_archive(in_archive)
print('Done.')
def add_chunk(self, id, data, stats):
if not self.txn_active:

7
borg/chunker.pyx
View file

@ -20,8 +20,11 @@ cdef extern from "_chunker.c":
cdef class Chunker:
cdef _Chunker *chunker
def __cinit__(self, window_size, chunk_mask, min_size, max_size, seed):
self.chunker = chunker_init(window_size, chunk_mask, min_size, max_size, seed & 0xffffffff)
def __cinit__(self, seed, chunk_min_exp, chunk_max_exp, hash_mask_bits, hash_window_size):
min_size = 1 << chunk_min_exp
max_size = 1 << chunk_max_exp
hash_mask = (1 << hash_mask_bits) - 1
self.chunker = chunker_init(hash_window_size, hash_mask, min_size, max_size, seed & 0xffffffff)
def chunkify(self, fd, fh=-1):
"""

12
borg/hashindex.pyx
View file

@ -11,7 +11,9 @@ cdef extern from "_hashindex.c":
HashIndex *hashindex_read(char *path)
HashIndex *hashindex_init(int capacity, int key_size, int value_size)
void hashindex_free(HashIndex *index)
void hashindex_summarize(HashIndex *index, long long *total_size, long long *total_csize, long long *unique_size, long long *unique_csize)
void hashindex_summarize(HashIndex *index, long long *total_size, long long *total_csize,
long long *unique_size, long long *unique_csize,
long long *total_unique_chunks, long long *total_chunks)
int hashindex_get_size(HashIndex *index)
int hashindex_write(HashIndex *index, char *path)
void *hashindex_get(HashIndex *index, void *key)
@ -179,9 +181,11 @@ cdef class ChunkIndex(IndexBase):
return iter
def summarize(self):
cdef long long total_size, total_csize, unique_size, unique_csize
hashindex_summarize(self.index, &total_size, &total_csize, &unique_size, &unique_csize)
return total_size, total_csize, unique_size, unique_csize
cdef long long total_size, total_csize, unique_size, unique_csize, total_unique_chunks, total_chunks
hashindex_summarize(self.index, &total_size, &total_csize,
&unique_size, &unique_csize,
&total_unique_chunks, &total_chunks)
return total_size, total_csize, unique_size, unique_csize, total_unique_chunks, total_chunks
cdef class ChunkKeyIterator:

23
borg/helpers.py
View file

@ -1,5 +1,6 @@
import argparse
import binascii
from collections import namedtuple
import grp
import msgpack
import os
@ -122,6 +123,18 @@ class Manifest:
self.id = self.key.id_hash(data)
self.repository.put(self.MANIFEST_ID, self.key.encrypt(data))
def list_archive_infos(self, sort_by=None, reverse=False):
# inexpensive Archive.list_archives replacement if we just need .name, .id, .ts
ArchiveInfo = namedtuple('ArchiveInfo', 'name id ts')
archives = []
for name, values in self.archives.items():
ts = parse_timestamp(values[b'time'].decode('utf-8'))
id = values[b'id']
archives.append(ArchiveInfo(name=name, id=id, ts=ts))
if sort_by is not None:
archives = sorted(archives, key=attrgetter(sort_by), reverse=reverse)
return archives
def prune_within(archives, within):
multiplier = {'H': 1, 'd': 24, 'w': 24*7, 'm': 24*31, 'y': 24*365}
@ -164,11 +177,14 @@ class Statistics:
self.usize += csize
def print_(self, label, cache):
total_size, total_csize, unique_size, unique_csize = cache.chunks.summarize()
total_size, total_csize, unique_size, unique_csize, total_unique_chunks, total_chunks = cache.chunks.summarize()
print()
print(' Original size Compressed size Deduplicated size')
print('%-15s %20s %20s %20s' % (label, format_file_size(self.osize), format_file_size(self.csize), format_file_size(self.usize)))
print('All archives: %20s %20s %20s' % (format_file_size(total_size), format_file_size(total_csize), format_file_size(unique_csize)))
print()
print(' Unique chunks Total chunks')
print('Chunk index: %20d %20d' % (total_unique_chunks, total_chunks))
def show_progress(self, item=None, final=False):
if not final:
@ -300,6 +316,11 @@ def timestamp(s):
raise ValueError
def ChunkerParams(s):
window_size, chunk_mask, chunk_min, chunk_max = s.split(',')
return int(window_size), int(chunk_mask), int(chunk_min), int(chunk_max)
def is_cachedir(path):
"""Determines whether the specified path is a cache directory (and
therefore should potentially be excluded from the backup) according to

5
borg/key.py
View file

@ -53,6 +53,7 @@ class KeyBase:
def __init__(self):
self.TYPE_STR = bytes([self.TYPE])
self.compression_level = 0
def id_hash(self, data):
"""Return HMAC hash using the "id" HMAC key
@ -83,7 +84,7 @@ class PlaintextKey(KeyBase):
return sha256(data).digest()
def encrypt(self, data):
return b''.join([self.TYPE_STR, zlib.compress(data)])
return b''.join([self.TYPE_STR, zlib.compress(data, self.compression_level)])
def decrypt(self, id, data):
if data[0] != self.TYPE:
@ -115,7 +116,7 @@ class AESKeyBase(KeyBase):
return HMAC(self.id_key, data, sha256).digest()
def encrypt(self, data):
data = zlib.compress(data)
data = zlib.compress(data, self.compression_level)
self.enc_cipher.reset()
data = b''.join((self.enc_cipher.iv[8:], self.enc_cipher.encrypt(data)))
hmac = HMAC(self.enc_hmac_key, data, sha256).digest()

5
borg/remote.py
View file

@ -141,7 +141,10 @@ class RemoteRepository:
self.r_fds = [self.stdout_fd]
self.x_fds = [self.stdin_fd, self.stdout_fd]
version = self.call('negotiate', 1)
try:
version = self.call('negotiate', 1)
except ConnectionClosed:
raise Exception('Server immediately closed connection - is Borg installed and working on the server?')
if version != 1:
raise Exception('Server insisted on using unsupported protocol version %d' % version)
self.id = self.call('open', location.path, create)

30
borg/repository.py
View file

@ -14,6 +14,7 @@ from .lrucache import LRUCache
MAX_OBJECT_SIZE = 20 * 1024 * 1024
MAGIC = b'BORG_SEG'
MAGIC_LEN = len(MAGIC)
TAG_PUT = 0
TAG_DELETE = 1
TAG_COMMIT = 2
@ -281,8 +282,8 @@ class Repository:
continue
try:
objects = list(self.io.iter_objects(segment))
except (IntegrityError, struct.error):
report_error('Error reading segment {}'.format(segment))
except IntegrityError as err:
report_error('Error reading segment {}: {}'.format(segment, err))
objects = []
if repair:
self.io.recover_segment(segment, filename)
@ -481,7 +482,7 @@ class LoggedIO:
os.mkdir(dirname)
self._write_fd = open(self.segment_filename(self.segment), 'ab')
self._write_fd.write(MAGIC)
self.offset = 8
self.offset = MAGIC_LEN
return self._write_fd
def get_fd(self, segment):
@ -504,19 +505,26 @@ class LoggedIO:
def iter_objects(self, segment, include_data=False):
fd = self.get_fd(segment)
fd.seek(0)
if fd.read(8) != MAGIC:
raise IntegrityError('Invalid segment header')
offset = 8
if fd.read(MAGIC_LEN) != MAGIC:
raise IntegrityError('Invalid segment magic')
offset = MAGIC_LEN
header = fd.read(self.header_fmt.size)
while header:
crc, size, tag = self.header_fmt.unpack(header)
try:
crc, size, tag = self.header_fmt.unpack(header)
except struct.error as err:
raise IntegrityError('Invalid segment entry header [offset {}]: {}'.format(offset, err))
if size > MAX_OBJECT_SIZE:
raise IntegrityError('Invalid segment object size')
rest = fd.read(size - self.header_fmt.size)
raise IntegrityError('Invalid segment entry size [offset {}]'.format(offset))
length = size - self.header_fmt.size
rest = fd.read(length)
if len(rest) != length:
raise IntegrityError('Segment entry data short read [offset {}]: expected: {}, got {} bytes'.format(
offset, length, len(rest)))
if crc32(rest, crc32(memoryview(header)[4:])) & 0xffffffff != crc:
raise IntegrityError('Segment checksum mismatch')
raise IntegrityError('Segment entry checksum mismatch [offset {}]'.format(offset))
if tag not in (TAG_PUT, TAG_DELETE, TAG_COMMIT):
raise IntegrityError('Invalid segment entry header')
raise IntegrityError('Invalid segment entry tag [offset {}]'.format(offset))
key = None
if tag in (TAG_PUT, TAG_DELETE):
key = rest[:32]

8
borg/testsuite/archiver.py
View file

@ -12,7 +12,7 @@ import unittest
from hashlib import sha256
from .. import xattr
from ..archive import Archive, ChunkBuffer, CHUNK_MAX
from ..archive import Archive, ChunkBuffer, CHUNK_MAX_EXP
from ..archiver import Archiver
from ..cache import Cache
from ..crypto import bytes_to_long, num_aes_blocks
@ -213,7 +213,7 @@ class ArchiverTestCase(ArchiverTestCaseBase):
sparse_support = sys.platform != 'darwin'
filename = os.path.join(self.input_path, 'sparse')
content = b'foobar'
hole_size = 5 * CHUNK_MAX # 5 full chunker buffers
hole_size = 5 * (1 << CHUNK_MAX_EXP) # 5 full chunker buffers
with open(filename, 'wb') as fd:
# create a file that has a hole at the beginning and end (if the
# OS and filesystem supports sparse files)
@ -400,9 +400,9 @@ class ArchiverTestCase(ArchiverTestCaseBase):
self.cmd('extract', '--dry-run', self.repository_location + '::test')
self.cmd('check', self.repository_location)
name = sorted(os.listdir(os.path.join(self.tmpdir, 'repository', 'data', '0')), reverse=True)[0]
with open(os.path.join(self.tmpdir, 'repository', 'data', '0', name), 'r+') as fd:
with open(os.path.join(self.tmpdir, 'repository', 'data', '0', name), 'r+b') as fd:
fd.seek(100)
fd.write('XXXX')
fd.write(b'XXXX')
self.cmd('check', self.repository_location, exit_code=1)
def test_readonly_repository(self):

26
borg/testsuite/chunker.py
View file

@ -1,27 +1,27 @@
from io import BytesIO
from ..chunker import Chunker, buzhash, buzhash_update
from ..archive import CHUNK_MAX
from ..archive import CHUNK_MAX_EXP
from . import BaseTestCase
class ChunkerTestCase(BaseTestCase):
def test_chunkify(self):
data = b'0' * int(1.5 * CHUNK_MAX) + b'Y'
parts = [bytes(c) for c in Chunker(2, 0x3, 2, CHUNK_MAX, 0).chunkify(BytesIO(data))]
data = b'0' * int(1.5 * (1 << CHUNK_MAX_EXP)) + b'Y'
parts = [bytes(c) for c in Chunker(0, 1, CHUNK_MAX_EXP, 2, 2).chunkify(BytesIO(data))]
self.assert_equal(len(parts), 2)
self.assert_equal(b''.join(parts), data)
self.assert_equal([bytes(c) for c in Chunker(2, 0x3, 2, CHUNK_MAX, 0).chunkify(BytesIO(b''))], [])
self.assert_equal([bytes(c) for c in Chunker(2, 0x3, 2, CHUNK_MAX, 0).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'fooba', b'rboobaz', b'fooba', b'rboobaz', b'fooba', b'rboobaz'])
self.assert_equal([bytes(c) for c in Chunker(2, 0x3, 2, CHUNK_MAX, 1).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'fo', b'obarb', b'oob', b'azf', b'oobarb', b'oob', b'azf', b'oobarb', b'oobaz'])
self.assert_equal([bytes(c) for c in Chunker(2, 0x3, 2, CHUNK_MAX, 2).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foob', b'ar', b'boobazfoob', b'ar', b'boobazfoob', b'ar', b'boobaz'])
self.assert_equal([bytes(c) for c in Chunker(3, 0x3, 3, CHUNK_MAX, 0).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobarboobaz' * 3])
self.assert_equal([bytes(c) for c in Chunker(3, 0x3, 3, CHUNK_MAX, 1).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobar', b'boo', b'bazfo', b'obar', b'boo', b'bazfo', b'obar', b'boobaz'])
self.assert_equal([bytes(c) for c in Chunker(3, 0x3, 3, CHUNK_MAX, 2).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foo', b'barboobaz', b'foo', b'barboobaz', b'foo', b'barboobaz'])
self.assert_equal([bytes(c) for c in Chunker(3, 0x3, 4, CHUNK_MAX, 0).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobarboobaz' * 3])
self.assert_equal([bytes(c) for c in Chunker(3, 0x3, 4, CHUNK_MAX, 1).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobar', b'boobazfo', b'obar', b'boobazfo', b'obar', b'boobaz'])
self.assert_equal([bytes(c) for c in Chunker(3, 0x3, 4, CHUNK_MAX, 2).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foob', b'arboobaz', b'foob', b'arboobaz', b'foob', b'arboobaz'])
self.assert_equal([bytes(c) for c in Chunker(0, 1, CHUNK_MAX_EXP, 2, 2).chunkify(BytesIO(b''))], [])
self.assert_equal([bytes(c) for c in Chunker(0, 1, CHUNK_MAX_EXP, 2, 2).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'fooba', b'rboobaz', b'fooba', b'rboobaz', b'fooba', b'rboobaz'])
self.assert_equal([bytes(c) for c in Chunker(1, 1, CHUNK_MAX_EXP, 2, 2).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'fo', b'obarb', b'oob', b'azf', b'oobarb', b'oob', b'azf', b'oobarb', b'oobaz'])
self.assert_equal([bytes(c) for c in Chunker(2, 1, CHUNK_MAX_EXP, 2, 2).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foob', b'ar', b'boobazfoob', b'ar', b'boobazfoob', b'ar', b'boobaz'])
self.assert_equal([bytes(c) for c in Chunker(0, 2, CHUNK_MAX_EXP, 2, 3).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobarboobaz' * 3])
self.assert_equal([bytes(c) for c in Chunker(1, 2, CHUNK_MAX_EXP, 2, 3).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobar', b'boobazfo', b'obar', b'boobazfo', b'obar', b'boobaz'])
self.assert_equal([bytes(c) for c in Chunker(2, 2, CHUNK_MAX_EXP, 2, 3).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foob', b'arboobaz', b'foob', b'arboobaz', b'foob', b'arboobaz'])
self.assert_equal([bytes(c) for c in Chunker(0, 3, CHUNK_MAX_EXP, 2, 3).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobarboobaz' * 3])
self.assert_equal([bytes(c) for c in Chunker(1, 3, CHUNK_MAX_EXP, 2, 3).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobarbo', b'obazfoobar', b'boobazfo', b'obarboobaz'])
self.assert_equal([bytes(c) for c in Chunker(2, 3, CHUNK_MAX_EXP, 2, 3).chunkify(BytesIO(b'foobarboobaz' * 3))], [b'foobarboobaz', b'foobarboobaz', b'foobarboobaz'])
def test_buzhash(self):
self.assert_equal(buzhash(b'abcdefghijklmnop', 0), 3795437769)

4
docs/_themes/local/static/local.css_t vendored
View file

@ -161,8 +161,8 @@ p.admonition-title:after {
}
div.note {
background-color: #0f5;
border-bottom: 2px solid #d22;
background-color: #002211;
border-bottom: 2px solid #22dd22;
}
div.seealso {

2
docs/faq.rst
View file

@ -51,7 +51,7 @@ Which file types, attributes, etc. are *not* preserved?
recreate them in any case). So, don't panic if your backup misses a UDS!
* The precise on-disk representation of the holes in a sparse file.
Archive creation has no special support for sparse files, holes are
backed up up as (deduplicated and compressed) runs of zero bytes.
backed up as (deduplicated and compressed) runs of zero bytes.
Archive extraction has optional support to extract all-zero chunks as
holes in a sparse file.

59
docs/installation.rst
View file

@ -62,21 +62,60 @@ Some of the steps detailled below might be useful also for non-git installs.
# optional: for unit testing
apt-get install fakeroot
# install virtualenv tool, create and activate a virtual env
apt-get install python-virtualenv
virtualenv --python=python3 borg-env
source borg-env/bin/activate # always do this before using!
# install some dependencies into virtual env
pip install cython # to compile .pyx -> .c
pip install tox pytest # optional, for running unit tests
pip install sphinx # optional, to build the docs
# get |project_name| from github, install it
git clone |git_url|
apt-get install python-virtualenv
virtualenv --python=python3 borg-env
source borg-env/bin/activate # always before using!
# install borg + dependencies into virtualenv
pip install cython # compile .pyx -> .c
pip install tox pytest # optional, for running unit tests
pip install sphinx # optional, to build the docs
cd borg
pip install -e . # in-place editable mode
# optional: run all the tests, on all supported Python versions
fakeroot -u tox
Korora / Fedora 21 installation (from git)
------------------------------------------
Note: this uses latest, unreleased development code from git.
While we try not to break master, there are no guarantees on anything.
Some of the steps detailled below might be useful also for non-git installs.
.. parsed-literal::
# Python 3.x (>= 3.2) + Headers, Py Package Installer
sudo dnf install python3 python3-devel python3-pip
# we need OpenSSL + Headers for Crypto
sudo dnf install openssl-devel openssl
# ACL support Headers + Library
sudo dnf install libacl-devel libacl
# optional: lowlevel FUSE py binding - to mount backup archives
sudo dnf install python3-llfuse fuse
# optional: for unit testing
sudo dnf install fakeroot
# get |project_name| from github, install it
git clone |git_url|
dnf install python3-virtualenv
virtualenv --python=python3 borg-env
source borg-env/bin/activate # always before using!
# install borg + dependencies into virtualenv
pip install cython # compile .pyx -> .c
pip install tox pytest # optional, for running unit tests
pip install sphinx # optional, to build the docs
cd borg
pip install -e . # in-place editable mode
# optional: run all the tests, on all supported Python versions
fakeroot -u tox

295
docs/internals.rst
View file

@ -6,38 +6,43 @@ Internals
This page documents the internal data structures and storage
mechanisms of |project_name|. It is partly based on `mailing list
discussion about internals`_ and also on static code analysis. It may
not be exactly up to date with the current source code.
discussion about internals`_ and also on static code analysis.
It may not be exactly up to date with the current source code.
Repository and Archives
-----------------------
|project_name| stores its data in a `Repository`. Each repository can
hold multiple `Archives`, which represent individual backups that
contain a full archive of the files specified when the backup was
performed. Deduplication is performed across multiple backups, both on
data and metadata, using `Segments` chunked with the Buzhash_
algorithm. Each repository has the following file structure:
data and metadata, using `Chunks` created by the chunker using the Buzhash_
algorithm.
Each repository has the following file structure:
README
simple text file describing the repository
simple text file telling that this is a |project_name| repository
config
description of the repository, includes the unique identifier. also
acts as a lock file
repository configuration and lock file
data/
directory where the actual data (`segments`) is stored
directory where the actual data is stored
hints.%d
undocumented
hints for repository compaction
index.%d
cache of the file indexes. those files can be regenerated with
``check --repair``
repository index
Config file
-----------
Each repository has a ``config`` file which which is a ``INI``
formatted file which looks like this::
Each repository has a ``config`` file which which is a ``INI``-style file
and looks like this::
[repository]
version = 1
@ -48,20 +53,35 @@ formatted file which looks like this::
This is where the ``repository.id`` is stored. It is a unique
identifier for repositories. It will not change if you move the
repository around so you can make a local transfer then decide to move
the repository in another (even remote) location at a later time.
the repository to another (even remote) location at a later time.
|project_name| will do a POSIX read lock on that file when operating
|project_name| will do a POSIX read lock on the config file when operating
on the repository.
Keys
----
The key to address the key/value store is usually computed like this:
key = id = id_hash(unencrypted_data)
The id_hash function is:
* sha256 (no encryption keys available)
* hmac-sha256 (encryption keys available)
Segments and archives
---------------------
|project_name| is a "filesystem based transactional key value
store". It makes extensive use of msgpack_ to store data and, unless
A |project_name| repository is a filesystem based transactional key/value
store. It makes extensive use of msgpack_ to store data and, unless
otherwise noted, data is stored in msgpack_ encoded files.
Objects referenced by a key (256bits id/hash) are stored inline in
files (`segments`) of size approx 5MB in ``repo/data``. They contain:
Objects referenced by a key are stored inline in files (`segments`) of approx.
5MB size in numbered subdirectories of ``repo/data``.
They contain:
* header size
* crc
@ -77,21 +97,26 @@ Tag is either ``PUT``, ``DELETE``, or ``COMMIT``. A segment file is
basically a transaction log where each repository operation is
appended to the file. So if an object is written to the repository a
``PUT`` tag is written to the file followed by the object id and
data. And if an object is deleted a ``DELETE`` tag is appended
data. If an object is deleted a ``DELETE`` tag is appended
followed by the object id. A ``COMMIT`` tag is written when a
repository transaction is committed. When a repository is opened any
``PUT`` or ``DELETE`` operations not followed by a ``COMMIT`` tag are
discarded since they are part of a partial/uncommitted transaction.
The manifest is an object with an id of only zeros (32 bytes), that
references all the archives. It contains:
The manifest
------------
The manifest is an object with an all-zero key that references all the
archives.
It contains:
* version
* list of archives
* list of archive infos
* timestamp
* config
Each archive contains:
Each archive info contains:
* name
* id
@ -102,21 +127,21 @@ each time.
The archive metadata does not contain the file items directly. Only
references to other objects that contain that data. An archive is an
object that contain metadata:
object that contains:
* version
* name
* items list
* list of chunks containing item metadata
* cmdline
* hostname
* username
* time
Each item represents a file or directory or
symlink is stored as an ``item`` dictionary that contains:
Each item represents a file, directory or other fs item and is stored as an
``item`` dictionary that contains:
* path
* list of chunks
* list of data chunks
* user
* group
* uid
@ -135,124 +160,136 @@ it and it is reset every time an inode's metadata is changed.
All items are serialized using msgpack and the resulting byte stream
is fed into the same chunker used for regular file data and turned
into deduplicated chunks. The reference to these chunks is then added
to the archive metadata. This allows the archive to store many files,
beyond the ``MAX_OBJECT_SIZE`` barrier of 20MB.
to the archive metadata.
A chunk is an object as well, of course. The chunk id is either
HMAC-SHA256_, when encryption is used, or a SHA256_ hash otherwise.
A chunk is stored as an object as well, of course.
Hints are stored in a file (``repo/hints``) and contain:
* version
* list of segments
* compact
Chunks
------
|project_name| uses a rolling checksum with Buzhash_ algorithm, with
window size of 4095 bytes (`0xFFF`), with a minimum of 1024, and triggers when
the last 16 bits of the checksum are null, producing chunks of 64kB on
average. All these parameters are fixed. The buzhash table is altered
by XORing it with a seed randomly generated once for the archive, and
stored encrypted in the keyfile.
|project_name| uses a rolling hash computed by the Buzhash_ algorithm, with a
window size of 4095 bytes (`0xFFF`), with a minimum chunk size of 1024 bytes.
It triggers (chunks) when the last 16 bits of the hash are zero, producing
chunks of 64kiB on average.
Indexes
-------
The buzhash table is altered by XORing it with a seed randomly generated once
for the archive, and stored encrypted in the keyfile.
There are two main indexes: the chunk lookup index and the repository
index. There is also the file chunk cache.
The chunk lookup index is stored in ``cache/chunk`` and is indexed on
the ``chunk hash``. It contains:
Indexes / Caches
----------------
* reference count
* size
* ciphered size
The repository index is stored in ``repo/index.%d`` and is also
indexed on ``chunk hash`` and contains:
* segment
* offset
The repository index files are random access but those files can be
recreated if damaged or lost using ``check --repair``.
Both indexes are stored as hash tables, directly mapped in memory from
the file content, with only one slot per bucket, but that spreads the
collisions to the following buckets. As a consequence the hash is just
a start position for a linear search, and if the element is not in the
table the index is linearly crossed until an empty bucket is
found. When the table is full at 90% its size is doubled, when it's
empty at 25% its size is halfed. So operations on it have a variable
complexity between constant and linear with low factor, and memory
overhead varies between 10% and 300%.
The file chunk cache is stored in ``cache/files`` and is indexed on
the ``file path hash`` and contains:
The files cache is stored in ``cache/files`` and is indexed on the
``file path hash``. At backup time, it is used to quickly determine whether we
need to chunk a given file (or whether it is unchanged and we already have all
its pieces).
It contains:
* age
* inode number
* size
* mtime_ns
* chunks hashes
* file inode number
* file size
* file mtime_ns
* file content chunk hashes
The inode number is stored to make sure we distinguish between
different files, as a single path may not be unique across different
archives in different setups.
The file chunk cache is stored as a python associative array storing
python objects, which generate a lot of overhead. This takes around
240 bytes per file without the chunk list, to be compared to at most
64 bytes of real data (depending on data alignment), and around 80
bytes per chunk hash (vs 32), with a minimum of ~250 bytes even if
only one chunk hash.
The files cache is stored as a python associative array storing
python objects, which generates a lot of overhead.
Indexes memory usage
--------------------
The chunks cache is stored in ``cache/chunks`` and is indexed on the
``chunk id_hash``. It is used to determine whether we already have a specific
chunk, to count references to it and also for statistics.
It contains:
Here is the estimated memory usage of |project_name| when using those
indexes.
* reference count
* size
* encrypted/compressed size
Repository index
40 bytes x N ~ 200MB (If a remote repository is
used this will be allocated on the remote side)
The repository index is stored in ``repo/index.%d`` and is indexed on the
``chunk id_hash``. It is used to determine a chunk's location in the repository.
It contains:
Chunk lookup index
44 bytes x N ~ 220MB
* segment (that contains the chunk)
* offset (where the chunk is located in the segment)
File chunk cache
probably 80-100 bytes x N ~ 400MB
The repository index file is random access.
Hints are stored in a file (``repo/hints.%d``).
It contains:
* version
* list of segments
* compact
hints and index can be recreated if damaged or lost using ``check --repair``.
The chunks cache and the repository index are stored as hash tables, with
only one slot per bucket, but that spreads the collisions to the following
buckets. As a consequence the hash is just a start position for a linear
search, and if the element is not in the table the index is linearly crossed
until an empty bucket is found.
When the hash table is almost full at 90%, its size is doubled. When it's
almost empty at 25%, its size is halved. So operations on it have a variable
complexity between constant and linear with low factor, and memory overhead
varies between 10% and 300%.
Indexes / Caches memory usage
-----------------------------
Here is the estimated memory usage of |project_name|:
chunk_count ~= total_file_size / 65536
repo_index_usage = chunk_count * 40
chunks_cache_usage = chunk_count * 44
files_cache_usage = total_file_count * 240 + chunk_count * 80
mem_usage ~= repo_index_usage + chunks_cache_usage + files_cache_usage
= total_file_count * 240 + total_file_size / 400
All units are Bytes.
It is assuming every chunk is referenced exactly once and that typical chunk size is 64kiB.
If a remote repository is used the repo index will be allocated on the remote side.
E.g. backing up a total count of 1Mi files with a total size of 1TiB:
mem_usage = 1 * 2**20 * 240 + 1 * 2**40 / 400 = 2.8GiB
Note: there is a commandline option to switch off the files cache. You'll save
some memory, but it will need to read / chunk all the files then.
In the above we assume 350GB of data that we divide on an average 64KB
chunk size, so N is around 5.3 million.
Encryption
----------
AES_ is used with CTR mode of operation (so no need for padding). A 64
bits initialization vector is used, a `HMAC-SHA256`_ is computed
on the encrypted chunk with a random 64 bits nonce and both are stored
in the chunk. The header of each chunk is : ``TYPE(1)`` +
``HMAC(32)`` + ``NONCE(8)`` + ``CIPHERTEXT``. Encryption and HMAC use
two different keys.
AES_ is used in CTR mode (so no need for padding). A 64bit initialization
vector is used, a `HMAC-SHA256`_ is computed on the encrypted chunk with a
random 64bit nonce and both are stored in the chunk.
The header of each chunk is : ``TYPE(1)`` + ``HMAC(32)`` + ``NONCE(8)`` + ``CIPHERTEXT``.
Encryption and HMAC use two different keys.
In AES CTR mode you can think of the IV as the start value for the
counter. The counter itself is incremented by one after each 16 byte
block. The IV/counter is not required to be random but it must NEVER be
reused. So to accomplish this |project_name| initializes the encryption counter
to be higher than any previously used counter value before encrypting
new data.
In AES CTR mode you can think of the IV as the start value for the counter.
The counter itself is incremented by one after each 16 byte block.
The IV/counter is not required to be random but it must NEVER be reused.
So to accomplish this |project_name| initializes the encryption counter to be
higher than any previously used counter value before encrypting new data.
To reduce payload size only 8 bytes of the 16 bytes nonce is saved in
the payload, the first 8 bytes are always zeroes. This does not affect
security but limits the maximum repository capacity to only 295
exabytes (2**64 * 16 bytes).
To reduce payload size, only 8 bytes of the 16 bytes nonce is saved in the
payload, the first 8 bytes are always zeros. This does not affect security but
limits the maximum repository capacity to only 295 exabytes (2**64 * 16 bytes).
Encryption keys are either a passphrase, passed through the
``BORG_PASSPHRASE`` environment or prompted on the commandline, or
stored in automatically generated key files.
Encryption keys are either derived from a passphrase or kept in a key file.
The passphrase is passed through the ``BORG_PASSPHRASE`` environment variable
or prompted for interactive usage.
Key files
---------
@ -274,22 +311,20 @@ enc_key
the key used to encrypt data with AES (256 bits)
enc_hmac_key
the key used to HMAC the resulting AES-encrypted data (256 bits)
the key used to HMAC the encrypted data (256 bits)
id_key
the key used to HMAC the above chunks, the resulting hash is
stored out of band (256 bits)
the key used to HMAC the plaintext chunk data to compute the chunk's id
chunk_seed
the seed for the buzhash chunking table (signed 32 bit integer)
Those fields are processed using msgpack_. The utf-8 encoded phassphrase
is encrypted with PBKDF2_ and SHA256_ using 100000 iterations and a
random 256 bits salt to give us a derived key. The derived key is 256
bits long. A `HMAC-SHA256`_ checksum of the above fields is generated
with the derived key, then the derived key is also used to encrypt the
above pack of fields. Then the result is stored in a another msgpack_
formatted as follows:
Those fields are processed using msgpack_. The utf-8 encoded passphrase
is processed with PBKDF2_ (SHA256_, 100000 iterations, random 256 bit salt)
to give us a derived key. The derived key is 256 bits long.
A `HMAC-SHA256`_ checksum of the above fields is generated with the derived
key, then the derived key is also used to encrypt the above pack of fields.
Then the result is stored in a another msgpack_ formatted as follows:
version
currently always an integer, 1
@ -315,3 +350,9 @@ The resulting msgpack_ is then encoded using base64 and written to the
key file, wrapped using the standard ``textwrap`` module with a header.
The header is a single line with a MAGIC string, a space and a hexadecimal
representation of the repository id.
Compression
-----------
Currently, zlib level 6 is used as compression.

116
docs/misc/create_chunker-params.txt Normal file
View file

@ -0,0 +1,116 @@
About borg create --chunker-params
==================================
--chunker-params CHUNK_MIN_EXP,CHUNK_MAX_EXP,HASH_MASK_BITS,HASH_WINDOW_SIZE
CHUNK_MIN_EXP and CHUNK_MAX_EXP give the exponent N of the 2^N minimum and
maximum chunk size. Required: CHUNK_MIN_EXP < CHUNK_MAX_EXP.
Defaults: 10 (2^10 == 1KiB) minimum, 23 (2^23 == 8MiB) maximum.
HASH_MASK_BITS is the number of least-significant bits of the rolling hash
that need to be zero to trigger a chunk cut.
Recommended: CHUNK_MIN_EXP + X <= HASH_MASK_BITS <= CHUNK_MAX_EXP - X, X >= 2
(this allows the rolling hash some freedom to make its cut at a place
determined by the windows contents rather than the min/max. chunk size).
Default: 16 (statistically, chunks will be about 2^16 == 64kiB in size)
HASH_WINDOW_SIZE: the size of the window used for the rolling hash computation.
Default: 4095B
Trying it out
=============
I backed up a VM directory to demonstrate how different chunker parameters
influence repo size, index size / chunk count, compression, deduplication.
repo-sm: ~64kiB chunks (16 bits chunk mask), min chunk size 1kiB (2^10B)
(these are attic / borg 0.23 internal defaults)
repo-lg: ~1MiB chunks (20 bits chunk mask), min chunk size 64kiB (2^16B)
repo-xl: 8MiB chunks (2^23B max chunk size), min chunk size 64kiB (2^16B).
The chunk mask bits was set to 31, so it (almost) never triggers.
This degrades the rolling hash based dedup to a fixed-offset dedup
as the cutting point is now (almost) always the end of the buffer
(at 2^23B == 8MiB).
The repo index size is an indicator for the RAM needs of Borg.
In this special case, the total RAM needs are about 2.1x the repo index size.
You see index size of repo-sm is 16x larger than of repo-lg, which corresponds
to the ratio of the different target chunk sizes.
Note: RAM needs were not a problem in this specific case (37GB data size).
But just imagine, you have 37TB of such data and much less than 42GB RAM,
then you'ld definitely want the "lg" chunker params so you only need
2.6GB RAM. Or even bigger chunks than shown for "lg" (see "xl").
You also see compression works better for larger chunks, as expected.
Duplication works worse for larger chunks, also as expected.
small chunks
============
$ borg info /extra/repo-sm::1
Command line: /home/tw/w/borg-env/bin/borg create --chunker-params 10,23,16,4095 /extra/repo-sm::1 /home/tw/win
Number of files: 3
Original size Compressed size Deduplicated size
This archive: 37.12 GB 14.81 GB 12.18 GB
All archives: 37.12 GB 14.81 GB 12.18 GB
Unique chunks Total chunks
Chunk index: 378374 487316
$ ls -l /extra/repo-sm/index*
-rw-rw-r-- 1 tw tw 20971538 Jun 20 23:39 index.2308
$ du -sk /extra/repo-sm
11930840 /extra/repo-sm
large chunks
============
$ borg info /extra/repo-lg::1
Command line: /home/tw/w/borg-env/bin/borg create --chunker-params 16,23,20,4095 /extra/repo-lg::1 /home/tw/win
Number of files: 3
Original size Compressed size Deduplicated size
This archive: 37.10 GB 14.60 GB 13.38 GB
All archives: 37.10 GB 14.60 GB 13.38 GB
Unique chunks Total chunks
Chunk index: 25889 29349
$ ls -l /extra/repo-lg/index*
-rw-rw-r-- 1 tw tw 1310738 Jun 20 23:10 index.2264
$ du -sk /extra/repo-lg
13073928 /extra/repo-lg
xl chunks
=========
(borg-env)tw@tux:~/w/borg$ borg info /extra/repo-xl::1
Command line: /home/tw/w/borg-env/bin/borg create --chunker-params 16,23,31,4095 /extra/repo-xl::1 /home/tw/win
Number of files: 3
Original size Compressed size Deduplicated size
This archive: 37.10 GB 14.59 GB 14.59 GB
All archives: 37.10 GB 14.59 GB 14.59 GB
Unique chunks Total chunks
Chunk index: 4319 4434
$ ls -l /extra/repo-xl/index*
-rw-rw-r-- 1 tw tw 327698 Jun 21 00:52 index.2011
$ du -sk /extra/repo-xl/
14253464 /extra/repo-xl/

130
docs/misc/create_compression.txt Normal file
View file

@ -0,0 +1,130 @@
data compression
================
borg create --compression N repo::archive data
Currently, borg only supports zlib compression. There are plans to expand this
to other, faster or better compression algorithms in the future.
N == 0 -> zlib level 0 == very quick, no compression
N == 1 -> zlib level 1 == quick, low compression
...
N == 9 -> zlib level 9 == slow, high compression
Measurements made on a Haswell Ultrabook, SSD storage, Linux.
Example 1: lots of relatively small text files (linux kernel src)
-----------------------------------------------------------------
N == 1 does a good job here, it saves the additional time needed for
compression because it needs to store less into storage (see N == 0).
N == 6 is also quite ok, a little slower, a little less repo size.
6 was the old default of borg.
High compression levels only give a little more compression, but take a lot
of cpu time.
$ borg create --stats --compression 0
------------------------------------------------------------------------------
Duration: 50.40 seconds
Number of files: 72890
Original size Compressed size Deduplicated size
This archive: 1.17 GB 1.18 GB 1.01 GB
Unique chunks Total chunks
Chunk index: 70263 82309
------------------------------------------------------------------------------
$ borg create --stats --compression 1
------------------------------------------------------------------------------
Duration: 49.29 seconds
Number of files: 72890
Original size Compressed size Deduplicated size
This archive: 1.17 GB 368.62 MB 295.22 MB
Unique chunks Total chunks
Chunk index: 70280 82326
------------------------------------------------------------------------------
$ borg create --stats --compression 5
------------------------------------------------------------------------------
Duration: 59.99 seconds
Number of files: 72890
Original size Compressed size Deduplicated size
This archive: 1.17 GB 331.70 MB 262.20 MB
Unique chunks Total chunks
Chunk index: 70290 82336
------------------------------------------------------------------------------
$ borg create --stats --compression 6
------------------------------------------------------------------------------
Duration: 1 minutes 13.64 seconds
Number of files: 72890
Original size Compressed size Deduplicated size
This archive: 1.17 GB 328.79 MB 259.56 MB
Unique chunks Total chunks
Chunk index: 70279 82325
------------------------------------------------------------------------------
$ borg create --stats --compression 9
------------------------------------------------------------------------------
Duration: 3 minutes 1.58 seconds
Number of files: 72890
Original size Compressed size Deduplicated size
This archive: 1.17 GB 326.57 MB 257.57 MB
Unique chunks Total chunks
Chunk index: 70292 82338
------------------------------------------------------------------------------
Example 2: large VM disk file (sparse file)
-------------------------------------------
The file's directory size is 80GB, but a lot of it is sparse (and reads as
zeros).
$ borg create --stats --compression 0
------------------------------------------------------------------------------
Duration: 13 minutes 48.47 seconds
Number of files: 1
Original size Compressed size Deduplicated size
This archive: 80.54 GB 80.55 GB 10.87 GB
Unique chunks Total chunks
Chunk index: 147307 177109
------------------------------------------------------------------------------
$ borg create --stats --compression 1
------------------------------------------------------------------------------
Duration: 15 minutes 31.34 seconds
Number of files: 1
Original size Compressed size Deduplicated size
This archive: 80.54 GB 6.68 GB 5.67 GB
Unique chunks Total chunks
Chunk index: 147309 177111
------------------------------------------------------------------------------
$ borg create --stats --compression 6
------------------------------------------------------------------------------
Duration: 18 minutes 57.54 seconds
Number of files: 1
Original size Compressed size Deduplicated size
This archive: 80.54 GB 6.19 GB 5.44 GB
Unique chunks Total chunks
Chunk index: 147307 177109
------------------------------------------------------------------------------

3
docs/usage.rst
View file

@ -50,6 +50,9 @@ Examples
NAME="root-`date +%Y-%m-%d`"
$ borg create /mnt/backup::$NAME / --do-not-cross-mountpoints
# Backup huge files with little chunk management overhead
$ borg create --chunker-params 19,23,21,4095 /mnt/backup::VMs /srv/VMs
.. include:: usage/extract.rst.inc