+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 mdadm verion 2.4.1 or later to use this
+ feature safely. 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.
+