[CentOS] Growing RAID5 on CentOS 4.6

Stephen Harris lists at spuddy.org
Fri Aug 22 18:36:49 UTC 2008


On Fri, Aug 22, 2008 at 02:25:20PM -0400, Ross S. W. Walker wrote:
> I don't think you can grow it without backing it up, destroying
> it, rebuilding it with 5 devices, then restoring.

You _can_... but it requires a newer kernel.  See, for example,

  http://linux-raid.osdl.org/index.php/Growing#Adding_partitions

Newer kernels have this option:

  config MD_RAID5_RESHAPE
        bool "Support adding drives to a raid-5 array"
        depends on MD_RAID456
        default y
        ---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.


But it seems this isn't available in the CentOS 4.6 kernel.

-- 

rgds
Stephen


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