Hugo Mills wrote:
> All -
>
> I turned this up while browsing through today's LKML postings. The
> main information is in the XFS FAQ:
>
> http://oss.sgi.com/projects/xfs/faq.html#wcache
>
> The potted summary is: if you have write cache enabled on your hard
> disk, then your system may be at risk of data corruption on power
> loss.
>
> - If you have write cache enabled on the disk, and write barriers
> enabled (see below) on the filesystem, then you are OK.
>
> - If you have write cache enabled on the disk, and battery-backed
> cache on the disk, then you are OK.
>
> - If you have write cache disabled on the disk, then you are OK.
>
> - In any other situation, you may be at risk.
>
> Barriers are a filesystem feature which allows the filesystem to
> flush the disks write cache to the platter at regular intervals. By
> default, XFS and ReiserFS have barriers enabled. *ext3 does not*
>
> So, if you're using ext3, you should do one or other of the
> following:
>
> - Disable the write cache on your hard disks (see the link at the top
> of this mail for details)
>
Hugo, this would explain why my CCTV server file system was corrupted in
a recent power cut as I thought using ext3 was supposed to prevent this
happening.
sudo hdparm -I /dev/sda | grep cache
* Write cache
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