Re: md RAID1 passes I/O errors to the filesystem despite having alive mirrors?

[Roman Mamedov <rm@romanrm.ru>]

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On Thu, 14 Mar 2013 21:43:14 -0600
Chris Murphy <lists@colorremedies.com> wrote:

> 
> On Mar 14, 2013, at 4:10 PM, Roman Mamedov <rm@romanrm.ru> wrote:
> > 
> > - shouldn't the reads have been quietly satisfied my md3 from sdf1, instead of just passing the buck^W error
> >  due to unreadable sdg1 to the higher (filesystem) layer?
> 
> What distro kernel and version?

Debian Testing, but I use vanilla 3.7.6 kernel, not distro's.

> Since you're not using btrfs raid1 there isn't a second copy maintained by btrfs itself, so it can't fix this. It's reporting a checksum failure for the single copy of data on the md raid1. It is getting the data elsewhere but it's btrfs saying that the checksum doesn't match.

So my guess (but that's already something like an accusation and not a founded
one at the moment :) that maybe mdadm failed to properly get data elsewhere,
and in case of errors it returned something like a zero-filled block, at which
btrfs correctly complained?..

Point is, I thought no user of md3 (be it btrfs or not) should have noticed any
errors "below" it, and in my case this turned out not to be the case.

-- 
With respect,
Roman

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