Re: XFS and XEN

[Michael Monnerie <michael.monnerie@is.it-management.at>]

On Dienstag 24 Februar 2009 Christoph Hellwig wrote:
> The difference is just that you actually see the
> corruption on XFS while it's pretty silent on extN.  If your Hardware
> (or Hypervisor) is not reliable you _will_ lose data.  Either
> silently or with a spectacular blowup if the filesystem actually has
> consistency checking (which XFS has a lot).

One more question: My hardware should be reliable: RAID controller, 
battery backed cache, disk write cache=off. So even in the event of a 
power fail, nothing should happen. The controller should write open 
blocks after reboot.

But it doesn't. I've retested: power off. On bootup, the XEN domU 
PostgreSQL reported errors again. This time of course I had a good 
backup from a minute before. But still: Shouldn't it be impossible for 
such an error to happen, as my hardware shouldn't eat any data? I'm 
trying to find out where the DB gets destroyed. Is it that "just" 
breaking within a transaction where XEN doesn't correctly fsync is 
enough, despite all hardware else configured well?

Damn, that's a complicated world.

mfg zmi
-- 
// Michael Monnerie, Ing.BSc    -----      http://it-management.at
// Tel: 0660 / 415 65 31                      .network.your.ideas.
// PGP Key:         "curl -s http://zmi.at/zmi.asc | gpg --import"
// Fingerprint: AC19 F9D5 36ED CD8A EF38  500E CE14 91F7 1C12 09B4
// Keyserver: wwwkeys.eu.pgp.net                  Key-ID: 1C1209B4

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs