Roy Sigurd Karlsbakk
2011-Mar-04 17:03 UTC
[zfs-discuss] [illumos-Developer] ZFS spare disk usage issue
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 element?rt imperativ for alle > > pedagoger ? unng? eksessiv anvendelse av idiomer med fremmed > > opprinnelse. I de fleste tilfeller eksisterer adekvate og > > relevante synonymer p? 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 element?rt imperativ for alle pedagoger ? unng? eksessiv anvendelse av idiomer med fremmed opprinnelse. I de fleste tilfeller eksisterer adekvate og relevante synonymer p? norsk.
Garrett D''Amore
2011-Mar-04 17:31 UTC
[zfs-discuss] [illumos-Developer] ZFS spare disk usage issue
On Fri, 2011-03-04 at 18:03 +0100, Roy Sigurd Karlsbakk wrote:> So should I post a bug, or is there one there already? > > Btw, I can''t reach http://bugs.illumos.org/ - it times outTry again in a few minutes... the server just got rebooted. - Garrett> > 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 element?rt imperativ for alle > > > pedagoger ? unng? eksessiv anvendelse av idiomer med fremmed > > > opprinnelse. I de fleste tilfeller eksisterer adekvate og > > > relevante synonymer p? 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 >