Re: Filesystem corruption on RAID1

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

Il 20-08-2017 15:07 Wols Lists ha scritto:
> Which is exactly what my "force integrity check on read" proposal would
> have achieved, but that generated so much heat and argument IN FAVOUR 
> of
> returning possibly corrupt data that I'll probably get flamed to high
> heaven if I bring it back up again.

I think the aversion to such an approach is due to:
a) a *big* performance degradation (you get the IOPs of a single disk);
b) the existence on all-encompassing checksummed filesystems as ZFS and 
BTRFS[1];
c) the difficulty to actually write such a code;
d) a understimating of how often can these data-corruption problem 
happens in real life.

I can not really blame MDRAID for what it provides, as it is incredibly 
flexible and very fast. Sure, a user-selectable option to auto 
discover/correct corrupted data would be great, but it seems that this 
is not the road MDRAID will ever take.

However, a possible solution would be to use dm-integrity on top of the 
single component devices of an MDRAID array. Give at look at stratis[2], 
it will be interesting...


[1] In the current state, I do not really trust BTRFS. I put much more 
hopes on ZoL...
[2] https://stratis-storage.github.io/StratisSoftwareDesign.pdf

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