Am 14.07.2017 um 02:52 schrieb Anthony Youngman:
On 14/07/17 01:32, Reindl Harald wrote:
Am 14.07.2017 um 00:34 schrieb Gionatan Danti:
Il 13-07-2017 23:34 Reindl Harald ha scritto:
maybe because the disk is, well, not in a good shape and don't know
that by itself
But the kernel *does* know that, as the dmesg entries clearly show.
Basically, some SATA commands timed-out and/or were aborted. As the
kernel reported these erros in dmesg, why do not use these
information to stop a failing disk?
because you won't be that happy when the kernel spits out a disk each
time a random SATA command times out - the 4 RAID10 disks on my
workstation are from 2011 and showed them too several times in the
past while they are just fine
Except, in the context of this thread, the alternative is CORRUPTED
DATA. I certainly know which one I would prefer, and that is a crashed
array!
If a *write* fails, then a failed array may well be the least of the
user's problems - and silent failure merely makes matters worse!
i doubt that you would repeat that if for whatever load condition a
random SATA timeout occours on both disks of a mirror and you lose some
TB of data while in *that case* not silent corruption or anything else
bad would have happened except a short lag
did you really read
http://strugglers.net/~andy/blog/2015/11/09/linux-software-raid-and-drive-timeouts/
or just ignored it on purpose?
I know, the problem is that linux isn't actually that good at
propagating errors back to user space, and I believe that's a fault of
POSIX. So fixing the problem might be a massive job - indeed I think it is.
But that's no excuse for mocking someone just because they want to be
told that the system has just gone and lost their work for them ...
nobody is mocking someone, i just explained why things are not as simple
as they appear and with a 2 disk mirror they are always complicated in
any error case by lack of quorum
Oh - and isn't that what raid is *supposed* to do? Kick a disk on a
write failure?
if things only would be that easy in the real world...
in doubt with a mirrored RAID without data checksums *you have no way*
to guarantee what is the correct data if something flips and "Except, in
the context of this thread" is nice but won't help in general and trying
to handle each and every bordercase with some workarounds would lead nowhere
yes, agreed, silent corruption is bad, hardware lying about data written
is bad, but if things would be that easy all that won't happen and
nobody would have spent time for develop checksummed filesystems
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
