[PATCH] md: Final stages of raid5 expand code
This patch adds raid5_reshape and end_reshape which will start and finish the
reshape processes.
raid5_reshape is only enabled in CONFIG_MD_RAID5_RESHAPE is set, to discourage
accidental use.
Read the 'help' for the CONFIG_MD_RAID5_RESHAPE entry.
and Make sure that you have backups, just in case.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index ac43f98..fd2aae1 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -127,6 +127,32 @@
If unsure, say Y.
+config MD_RAID5_RESHAPE
+ bool "Support adding drives to a raid-5 array (experimental)"
+ depends on MD_RAID5 && EXPERIMENTAL
+ ---help---
+ A RAID-5 set can be expanded by adding extra drives. This
+ requires "restriping" the array which means (almost) every
+ block must be written to a different place.
+
+ This option allows such restriping to be done while the array
+ is online. However it is still EXPERIMENTAL code. It should
+ work, but please be sure that you have backups.
+
+ You will need a version of mdadm newer than 2.3.1. During the
+ early stage of reshape there is a critical section where live data
+ is being over-written. A crash during this time needs extra care
+ for recovery. The newer mdadm takes a copy of the data in the
+ critical section and will restore it, if necessary, after a crash.
+
+ The mdadm usage is e.g.
+ mdadm --grow /dev/md1 --raid-disks=6
+ to grow '/dev/md1' to having 6 disks.
+
+ Note: The array can only be expanded, not contracted.
+ There should be enough spares already present to make the new
+ array workable.
+
config MD_RAID6
tristate "RAID-6 mode"
depends on BLK_DEV_MD