I understand that some of it may be a simple bug, but should it hang _all_ the 
pools? That's what happens when the third drive is removed... 

roy 

----- Original Message -----


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 < r...@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 
r...@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. 

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-- 

Eric Schrock 
Delphix 


275 Middlefield Road, Suite 50 
Menlo Park, CA 94025 
http://www.delphix.com 



-- 
Vennlige hilsener / Best regards 

roy 
-- 
Roy Sigurd Karlsbakk 
(+47) 97542685 
r...@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. 
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