linux-ext4.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [patch 0/4] Journal guided resync and support
@ 2009-10-01 22:39 scjody
  2009-10-01 22:39 ` [patch 1/4] [md] Add SKIP_RESYNC ioctl scjody
                   ` (4 more replies)
  0 siblings, 5 replies; 9+ messages in thread
From: scjody @ 2009-10-01 22:39 UTC (permalink / raw)
  To: linux-ext4, linux-raid; +Cc: linux-kernel, Andreas Dilger

This is an updated implementation of journal guided resync, intended to be
suitable for production systems.  This feature addresses the problem with RAID
arrays that take too long to resync - similar to the existing MD write-intent
bitmap feature, we resync only the stripes that were undergoing writes at the
time of the crash.  Unlike write-intent bitmaps, our testing shows very little
performance degredation as a result of the feature - around 3-5% vs around 30%
for bitmaps.

This feature is based on work described in this paper:
http://www.usenix.org/events/fast05/tech/denehy.html

As a summary, we introduce a new data write mode known as declared mode.  This
is based on ordered mode except that a list of blocks to be written during the
current transaction is added to the journal before the blocks themselves are
written to the disk.  Then, if the system crashes, we can resync only those
blocks during journal replay and skip the rest of the resync of the RAID array.

The changes consist of patches to ext3, jbd, MD, and the raid456 personality.
These patches are currently against the RHEL 5 kernel 2.6.18-128.1.6.  Porting
to ext4/jbd2 and a more modern kernel is a TODO item.

Cheers,
Jody

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2009-10-02 15:53 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-10-01 22:39 [patch 0/4] Journal guided resync and support scjody
2009-10-01 22:39 ` [patch 1/4] [md] Add SKIP_RESYNC ioctl scjody
2009-10-01 22:39 ` [patch 2/4] [md] Add RESYNC_RANGE ioctl scjody
2009-10-01 22:39 ` [patch 3/4] [jbd] Add support for journal guided resync scjody
2009-10-01 23:39   ` Andrew Morton
2009-10-01 22:39 ` [patch 4/4] [ext3] Add journal guided resync (data=declared mode) scjody
2009-10-02  1:51   ` Neil Brown
2009-10-02 15:53     ` Jody McIntyre
2009-10-02  0:36 ` [patch 0/4] Journal guided resync and support Andi Kleen

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).