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.
// Michael Monnerie, Ing.BSc ----- http://it-management.at
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