diff --git a/sys/geom/geom_dev.c b/sys/geom/geom_dev.c
index 8b560abe37b..af05618f163 100644
--- a/sys/geom/geom_dev.c
+++ b/sys/geom/geom_dev.c
@@ -323,7 +323,12 @@ g_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread
 			return (ENOENT);
 		strlcpy(data, pp->name, i);
 		break;
-
+	case DIOCGSTRIPESIZE:
+		*(off_t *)data = cp->provider->stripesize;
+		break;
+	case DIOCGSTRIPEOFFSET:
+		*(off_t *)data = cp->provider->stripeoffset;
+		break;
 	default:
 		if (cp->provider->geom->ioctl != NULL) {
 			error = cp->provider->geom->ioctl(cp->provider, cmd, data, fflag, td);
diff --git a/sys/sys/disk.h b/sys/sys/disk.h
index 4fe2e09c22f..422229ef69c 100644
--- a/sys/sys/disk.h
+++ b/sys/sys/disk.h
@@ -104,4 +104,16 @@ void disk_err(struct bio *bp, const char *what, int blkdone, int nl);
 	 * must be at least MAXPATHLEN bytes long.
 	 */
 
+#define DIOCGSTRIPESIZE	_IOR('d', 139, off_t)	/* Get stripe size in bytes */
+	/*-
+	 * Get the size of the device's optimal access block in bytes.
+	 * This should be a multiple of the sectorsize.
+	 */
+
+#define DIOCGSTRIPEOFFSET _IOR('d', 140, off_t)	/* Get stripe offset in bytes */
+	/*-
+	 * Get the offset of the first device's optimal access block in bytes.
+	 * This should be a multiple of the sectorsize.
+	 */
+
 #endif /* _SYS_DISK_H_ */