Re: Filesystem corruption on RAID1

[Gionatan Danti <g.danti@assyoma.it>]

Il 21-08-2017 01:22 Chris Murphy ha scritto:
> Another way is to split the mirror (make one device faulty), and then
> fix the remaining drive (now degraded). If that goes well, the 2nd
> device can be re-added. Here's a caveat thought: how it resync's will
> depend on the write-intent bitmap being present. I have no idea if
> write-intent bitmaps on two drives can get out of sync and what the
> ensuing behavior is, but I'd like to think md will discover the fixed
> drive event count is higher than the re-added one, and if necessary
> does a full resync, rather than possibly re-introducing any
> corruption.

On the corruption I am replicating (brief SATA power interruptions), the 
event count of both drives where identical, and so was the write bitmap 
(not always, thought).

To be 100% sure to completly copy from the mirror device, you had to 
re-add the corrupted driver as a spare, by using "--add-spare". From the 
man page:

"--add-spare
Add a device as a spare. This is similar to --add except that it does 
not attempt --re-add first. The device will be added as a spare even if 
it looks like it could be an recent member of the array."

Regards.

-- 
Danti Gionatan
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