svn commit: r266766 - vendor-sys/illumos/dist/common/zfs vendor-sys/illumos/dist/uts/common/fs/zfs vendor-sys/illumos/dist/uts/common/fs/zfs/sys vendor-sys/illumos/dist/uts/common/sys/fs vendor/ill...

[Xin LI]

Author: delphij
Date: Tue May 27 19:05:26 2014
New Revision: 266766
URL: http://svnweb.freebsd.org/changeset/base/266766

Log:
  3835 zfs need not store 2 copies of all metadata
  
  illumos/illumos-gate at edf345e6b8342e8627ec20ce821a977a62cee19d

Modified:
  vendor/illumos/dist/man/man1m/zfs.1m

Changes in other areas also in this revision:
Modified:
  vendor-sys/illumos/dist/common/zfs/zfs_prop.c
  vendor-sys/illumos/dist/uts/common/fs/zfs/dmu.c
  vendor-sys/illumos/dist/uts/common/fs/zfs/dmu_objset.c
  vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dmu.h
  vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dmu_objset.h
  vendor-sys/illumos/dist/uts/common/sys/fs/zfs.h

Modified: vendor/illumos/dist/man/man1m/zfs.1m
==============================================================================
--- vendor/illumos/dist/man/man1m/zfs.1m	Tue May 27 19:04:38 2014	(r266765)
+++ vendor/illumos/dist/man/man1m/zfs.1m	Tue May 27 19:05:26 2014	(r266766)
@@ -22,7 +22,7 @@
 .\"
 .\" Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
 .\" Copyright 2011 Joshua M. Clulow <josh at sysmgr.org>
-.\" Copyright (c) 2013 by Delphix. All rights reserved.
+.\" Copyright (c) 2014 by Delphix. All rights reserved.
 .\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 .\" Copyright 2013 Nexenta Systems, Inc.  All Rights Reserved.
 .\" Copyright (c) 2014, Joyent, Inc. All rights reserved.
@@ -1256,6 +1256,37 @@ This property can also be referred to by
 .sp
 .ne 2
 .na
+\fB\fBredundant_metadata\fR=\fBall\fR | \fBmost\fR\fR
+.ad
+.sp .6
+.RS 4n
+Controls what types of metadata are stored redundantly.  ZFS stores an
+extra copy of metadata, so that if a single block is corrupted, the
+amount of user data lost is limited.  This extra copy is in addition to
+any redundancy provided at the pool level (e.g. by mirroring or RAID-Z),
+and is in addition to an extra copy specified by the \fBcopies\fR
+property (up to a total of 3 copies).  For example if the pool is
+mirrored, \fBcopies\fR=2, and \fBredundant_metadata\fR=most, then ZFS
+stores 6 copies of most metadata, and 4 copies of data and some
+metadata.
+.sp
+When set to \fBall\fR, ZFS stores an extra copy of all metadata.  If a
+single on-disk block is corrupt, at worst a single block of user data
+(which is \fBrecordsize\fR bytes long) can be lost.
+.sp
+When set to \fBmost\fR, ZFS stores an extra copy of most types of
+metadata.  This can improve performance of random writes, because less
+metadata must be written.  In practice, at worst about 100 blocks (of
+\fBrecordsize\fR bytes each) of user data can be lost if a single
+on-disk block is corrupt.  The exact behavior of which metadata blocks
+are stored redundantly may change in future releases.
+.sp
+The default value is \fBall\fR.
+.RE
+
+.sp
+.ne 2
+.na
 \fB\fBrefquota\fR=\fIsize\fR | \fBnone\fR\fR
 .ad
 .sp .6