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Re: XFS filesystem corruption

To: Emmanuel Florac <eflorac@xxxxxxxxxxxxxx>
Subject: Re: XFS filesystem corruption
From: Ric Wheeler <rwheeler@xxxxxxxxxx>
Date: Wed, 06 Mar 2013 18:12:06 -0500
Cc: Julien FERRERO <jferrero06@xxxxxxxxx>, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20130306232100.6286f640@xxxxxxxxxxxxxx>
References: <CAPcwv6wZJSBtgF-L6KNSn6N6Y+wUZJFXdbcg+zYRwoaB2sDdjw@xxxxxxxxxxxxxx> <20130306161519.2c28d911@xxxxxxxxxxxxxx> <CAPcwv6wqv0b_CPqDpBfOwVDg23uBi=tpGQSy9XuH2uWS5oVMWQ@xxxxxxxxxxxxxx> <20130306232100.6286f640@xxxxxxxxxxxxxx>
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On 03/06/2013 05:21 PM, Emmanuel Florac wrote:
Le Wed, 6 Mar 2013 17:16:31 +0100 vous Ãcriviez:

  I don't think the H/W RAID is
the issue since we have the same corruption with other setup without
H/W RAID.
HW RAID may exacerbate the problem. XFS is absolutely, definitely not
"brutal power off" safe. All linux systems from this century are
perfectly able to turn themselves off properly at a single press of the
power button; the only safe options are educating the users or mounting
the filesystem read-only.

And yes, the ls garbled output is caracteristic of a filesystem
corruption.


We actually test brutal "Power off" for xfs, ext4 and other file systems. If your storage is configured properly and you have barriers enabled, they all pass without corruption.

What hardware raid cards can do is to hide a volatile write cache. Either on the raid HBA itself or, even worse, on the backend disks behind the card. S-ata disks tend to default to write cache enabled and need to be checked especially careful (sas drives tend to be write cache disabled by default).

ric

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