Re: config question (external raid, external log?)

[Ragnar Kjørstad <xfs@xxxxxxxxxxxxxxxxxxx>]

On Mon, May 27, 2002 at 07:14:26PM +0000, Robert Sander wrote:
> On Mon, 27 May 2002 16:36:24 +0000 (UTC),
>  utz lehmann <xfs@xxxxxxxxxx> wrote:
> > A warning. All SCSI to IDE RAID Systems i know have non battery backuped
> > cache. In the case of a power outage all unwritten data (and filesystem
> > metadata) in the RAID cache is lost. This cause filesystem corruption.
> > Running a journaled fs with a volatile cache is not recomended.
> 
> Thanks for the warning but the system will have a UPS with enough
> capacity to savely shutdown if the power does not return within 5
> minutes.

The problem remains for crashes or hangs.
Of course that neven happens :)

It causes filesystem corruption for non-journaled filesystems as well,
btw - only they will run fsck on reboot, so you don't risk _mounting_
the corrupted filesystem and making it worse.

If you care at all about your data, do _not_ use non-battery backed
writeback cache. (read cache doesn't need to be battery backed).


-- 
Ragnar Kjorstad
Big Storage