xfs data loss

[Eric Sandeen]

Passerone, Daniele wrote:
> I would like to ask mr. Peter Grandi, whether it is really necessary
> to delivery ist vaste knowledge in such a harsh way. Is this the
> habit of this mailing list?

Not generally.

> Apart from that, thank you for you help. I understand that RAID5 is
> not the ideal solution for that system, and I admit that in the
> urgence of solving the /md4 problem I miswrote the problem of /md6,
> which of course was "erased" and not "repaired".
> 
> But apart from that, it is not as easy to backup 20 TB, so we decided
> to set it as data storage leaving the responsibilty of the backup to
> our users. I do not consider it completely absurd.

I think others have pointed out, though, that you start -increasing- the 
risk of failure at a certain point...

> Moreover, when a raid loses 2 devices, and the devices are still ok,
> it is possible to reassemble the raid by assuming the devices clean.
> 
> This is not the case for /Raid/md4, where apparently all devices are
> there.

This all seems most likely to be a raid failure problem, but it's hard 
to know.  I can't imagine why you're getting suddenly-disappearing 
directories without a reboot or even a single error message; I just 
don't know what to make of that.

-Eric