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From: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
To: Anton Shepelev <anton.txt@gmail.com>, linux-btrfs@vger.kernel.org
Subject: Re: CRC mismatch
Date: Tue, 16 Oct 2018 11:42:49 -0400	[thread overview]
Message-ID: <f2df5862-ae3e-5808-4f00-e153f604df60@gmail.com> (raw)
In-Reply-To: <20181016183051.788a79297af47a9798a0c0e3@gmail.com>

On 2018-10-16 11:30, Anton Shepelev wrote:
> Hello, all
> 
> What may be the reason of a CRC mismatch on a BTRFS file in
> a virutal machine:
> 
>     csum failed ino 175524 off 1876295680 csum 451760558
>     expected csum 1446289185
> 
> Shall I seek the culprit in the host machine on in the guest
> one?  Supposing the host machine healty, what operations on
> the gueest might have caused a CRC mismatch?
> 
Possible causes include:

* On the guest side:
   - Unclean shutdown of the guest system (not likely even if this did 
happen).
   - A kernel bug on in the guest.
   - Something directly modifying the block device (also not very likely).

* On the host side:
   - Unclean shutdown of the host system without properly flushing data 
from the guest.  Not likely unless you're using an actively unsafe 
caching mode for the guest's storage back-end.
   - At-rest data corruption in the storage back-end.
   - A bug in the host-side storage stack.
   - A transient error in the host-side storage stack.
   - A bug in the hypervisor.
   - Something directly modifying the back-end storage.

Of these, the statistically most likely location for the issue is 
probably the storage stack on the host.

  reply	other threads:[~2018-10-16 15:42 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-16 15:30 CRC mismatch Anton Shepelev
2018-10-16 15:42 ` Austin S. Hemmelgarn [this message]
2018-10-16 20:27   ` Chris Murphy
2018-10-17  9:15     ` Anton Shepelev
2018-10-17 11:59     ` Austin S. Hemmelgarn
2018-10-18 12:02 ` Anton Shepelev
2018-10-18 12:34   ` Austin S. Hemmelgarn

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