raid repair checkpoint enhancement

raid repair checkpoint enhancement

[Ryan, MichaelS (ENG Redmond)]

Hi all.

If a device reboots during a raid repair operation ("echo repair > /sys/block/md0/md/sync_action"), the raid repair is interrupted and not restarted. For devices that are shutdown nightly, this could prevent a raid repair from ever getting to the far reaches of the array.  I'd like to see an enhancement that would checkpoint the raid repair operation on shutdown similar to how a sync operation is checkpointed.  Preferably, the raid repair would be restarted automatically on the next boot at the checkpoint location.  Alternatively it could require user input to restart the operation at either the checkpoint location, or at the beginning.

Any thoughts on this enhancement?
Thanks
- Michael

Re: raid repair checkpoint enhancement

[NeilBrown]

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On Thu, 4 Oct 2012 13:26:35 -0400 "Ryan, MichaelS (ENG Redmond)"
<michaels.ryan@emc.com> wrote:

> 
> Hi all.
> 
> If a device reboots during a raid repair operation ("echo repair > /sys/block/md0/md/sync_action"), the raid repair is interrupted and not restarted. For devices that are shutdown nightly, this could prevent a raid repair from ever getting to the far reaches of the array.  I'd like to see an enhancement that would checkpoint the raid repair operation on shutdown similar to how a sync operation is checkpointed.  Preferably, the raid repair would be restarted automatically on the next boot at the checkpoint location.  Alternatively it could require user input to restart the operation at either the checkpoint location, or at the beginning.
> 
> Any thoughts on this enhancement?

You can do this yourself with some scripting.
Before you shut down, record the first number in
    /sys/block/mdXX/md/sync_completed
When on reboot, write that number to 
    /sys/block/mdXX/md/sync_min
before writing 'repair' to 'sync_action'.

NeilBrown

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