XFS filesystem corruption

[Ric Wheeler]

On 03/06/2013 05:21 PM, Emmanuel Florac wrote:
> Le Wed, 6 Mar 2013 17:16:31 +0100 vous écriviez:
>
>>   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