From fd71d3ebeed399892ef1f286cd7ea1209dd1f601 Mon Sep 17 00:00:00 2001
From: Rick Macklem <rmacklem@FreeBSD.org>
Date: Sun, 10 Aug 2014 20:05:13 +0000
Subject: [PATCH] Document the use of the vfs.nfsd sysctls that control the
 size of the NFS server's DRC for TCP. This is a content change.

MFC after:	1 week
---
 usr.sbin/nfsd/nfsd.8 | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/usr.sbin/nfsd/nfsd.8 b/usr.sbin/nfsd/nfsd.8
index d865d7ea4f7..660e5e88a93 100644
--- a/usr.sbin/nfsd/nfsd.8
+++ b/usr.sbin/nfsd/nfsd.8
@@ -28,7 +28,7 @@
 .\"	@(#)nfsd.8	8.4 (Berkeley) 3/29/95
 .\" $FreeBSD$
 .\"
-.Dd July 18, 2014
+.Dd August 10, 2014
 .Dt NFSD 8
 .Os
 .Sh NAME
@@ -175,6 +175,24 @@ utility
 would then be used to block nfs-related packets that come in on the outside
 interface.
 .Pp
+If the server has stopped servicing clients and has generated a console message
+like
+.Dq Li "nfsd server cache flooded..." ,
+the value for vfs.nfsd.tcphighwater needs to be increased.
+This should allow the server to again handle requests without a reboot.
+Also, you may want to consider decreasing the value for
+vfs.nfsd.tcpcachetimeo to several minutes (in seconds) instead of 12 hours
+when this occurs.
+.Pp
+Unfortunately making vfs.nfsd.tcphighwater too large can result in the mbuf
+limit being reached, as indicated by a console message
+like
+.Dq Li "kern.ipc.nmbufs limit reached" .
+If you cannot find values of the above
+.Nm sysctl
+values that work, you can disable the DRC cache for TCP by setting
+vfs.nfsd.cachetcp to 0.
+.Pp
 The
 .Nm
 utility has to be terminated with