[illumos-Discuss] [illumos-Developer] ZFS spare disk usage issue

[Roy Sigurd Karlsbakk]

So should I post a bug, or is there one there already?

Btw, I can't reach http://bugs.illumos.org/ - it times out

roy

----- Original Message -----
> We've talked about this, and I will be putting together a fix for this
> incorrect state handling. :-)
> 
> - Garrett
> 
> On Fri, 2011-03-04 at 11:50 -0500, Eric Schrock wrote:
> > This looks like a pretty simple bug. The issue is that the state of
> > the SPARE vdev is being reported as REMOVED instead of DEGRADED. If
> > it were the latter (as it should be), then everything would work
> > just
> > fine. Please file a bug at bugs.illumos.org.
> >
> >
> > On a side note, this continues to expose the overly simplistic vdev
> > state model used by ZFS (one which I can take a bulk of the
> > responsibility for). Back before the days of ditto blocks and
> > SPA3.0,
> > it was sufficient to model state as a fairly binary proposition. But
> > this now has ramifications that don't necessarily make sense. For
> > example, one may be able open a pool even if a toplevel vdev is
> > faulted. And even when a spare has finished resilvering, it's left
> > in
> > the DEGRADED state, which has implications for allocation policies
> > (though I remember discussions around changing this). But the pool
> > state is derived directly from the toplevel vdev state, so if you
> > switch spares to be ONLINE, then 'zpool status' would think your
> > pool
> > is perfectly healthy. In this case it's true from a data protection
> > standpoint, but not necessarily from a "all is well in the world"
> > standpoint, as you are down one spare, and that spare may not have
> > the
> > same RAS properties as other devices in your RAID-Z stripe (it may
> > put
> > 3 disks on the same controller in one stripe, for example).
> >
> >
> > - Eric
> >
> > On Fri, Mar 4, 2011 at 7:06 AM, Roy Sigurd Karlsbakk
> > <roy at karlsbakk.net> wrote:
> >         Hi all
> >
> >         I just did a small test on RAIDz2 to check whether my
> >         suspicion was right about ZFS not treating spares as
> >         replicas/copies of drives, and I think I've found it true.
> >         The
> >         short story: If two spares replaces two drives in raidz2,
> >         losing a third drive, even with the spares active, makes the
> >         pool unavailable. See full report on
> >
> >         ODT: http://karlsbakk.net/ZFS/ZFS%20Spare%20disk%20usage.odt
> >         PDF: http://karlsbakk.net/ZFS/ZFS%20Spare%20disk%20usage.pdf
> >
> >         Vennlige hilsener / Best regards
> >
> >         roy
> >         --
> >         Roy Sigurd Karlsbakk
> >         (+47) 97542685
> >         roy at karlsbakk.net
> >         http://blogg.karlsbakk.net/
> >         --
> >         I all pedagogikk er det essensielt at pensum presenteres
> >         intelligibelt. Det er et elementært imperativ for alle
> >         pedagoger å unngå eksessiv anvendelse av idiomer med fremmed
> >         opprinnelse. I de fleste tilfeller eksisterer adekvate og
> >         relevante synonymer på norsk.
> >
> >         _______________________________________________
> >         Developer mailing list
> >         Developer at lists.illumos.org
> >         http://lists.illumos.org/m/listinfo/developer
> >
> >
> >
> > --
> > Eric Schrock
> > Delphix
> >
> >
> > 275 Middlefield Road, Suite 50
> > Menlo Park, CA 94025
> > http://www.delphix.com
> >
> >
> > _______________________________________________
> > Developer mailing list
> > Developer at lists.illumos.org
> > http://lists.illumos.org/m/listinfo/developer

-- 
Vennlige hilsener / Best regards

roy
--
Roy Sigurd Karlsbakk
(+47) 97542685
roy at karlsbakk.net
http://blogg.karlsbakk.net/
--
I all pedagogikk er det essensielt at pensum presenteres intelligibelt. Det er et elementært imperativ for alle pedagoger å unngå eksessiv anvendelse av idiomer med fremmed opprinnelse. I de fleste tilfeller eksisterer adekvate og relevante synonymer på norsk.