Re: Filesystem corruption on RAID1

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

Il 17-08-2017 23:21 Gionatan Danti ha scritto:
> Il 17-08-2017 23:01 Roger Heflin ha scritto:
>> But even if you figured out which it was, you would have no way to
>> know what writes were still sitting in the cache, it could be pretty
>> much any writes from the last few seconds (or longer depending on how
>> exactly the drive firmware works), and it would add additional
>> complexity to keep a list of recent writes to validate actually
>> happened in the case of an unexpected drive reset.  This is probably
>> more of a avoid this failure condition since this failure condition is
>> not a normal failure mode and more of a very rare failure mode.
> 
> Yes, but having identified the power-cycled disk, the system can not
> take the most sensible action.

Sorry, this should read:
"Yes, but having identified the power-cycled disk, the system can *now* 
take the most sensible action"

> For example, it can re-sync it with its mirror disk, basically
> treating it as a --add-spare action.
> Or it can simply considering the disk as failing, kicking off it from
> the array and sending an alert email.
> 
> What the system should not do is doing nothing: as differences
> accumulates, reading from the array become non-deterministic. In other
> words, two reads can produce two different results, based on what disk
> was queried. This *will* cause all sort of problems.
> 
> Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8