Re: Reshape stalled at first badblock location (was: RAID 5 --assemble doesn't recognize all overlays as component devices)

[NeilBrown <neilb@suse.com>]

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On Tue, Feb 21 2017, Shaohua Li wrote:

>
> Add Neil and Jes.
>
> Yes, there were similar reports before. When reshape finds nadblocks, the
> reshape will do an infinite loop without any progress. I think there are two
> things we need to do:
>
> - Make reshape more robust. Maybe reshape should bail out if badblocks found.
> - Add an option in mdadm to force reset badblocks

The second of these is already possible
Commit: 6dd16dac4001 ("Add --update=force-no-bbl.")

It isn't documented though, and only works during "assemble", not on an
active array.
Writing to the "bad" blocks should remove the "bad" status.  It would be
nice if mdadm could locate the bad blocks, map them to array blocks,
trigger a limited "resync" if there are any good copies, or write zeros
if there aren't.

And yes; reshape should be more robust...  if only we had a pool of
developers, eager to work on these problems :-)

NeilBrown

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