How do I add a spare to multiple pools?

[rcstevensonaz]

I created a vdev 'spare' as type spare.

I was able to use Disks|ZFS|Pools|Tools command "spare add" to add that spare vdev to my pool 'mediap'.

Code: Select all

  pool: mediap
 state: ONLINE
 scan: none requested
config:

	NAME          STATE     READ WRITE CKSUM
	mediap        ONLINE       0     0     0
	  raidz2-0    ONLINE       0     0     0
	    ada2.nop  ONLINE       0     0     0
	    ada4.nop  ONLINE       0     0     0
	    da2.nop   ONLINE       0     0     0
	    da6.nop   ONLINE       0     0     0
	spares
	  da4.nop     AVAIL

errors: No known data errors

But then when I try to execute the spare add command for pool 'rootp', the Hot Spare pull down list is empty.

What am I missing? And thanks.

[raulfg3]

one spare disk eg: da4.nop can't be used as spare of other pool , each spare can be used only in one pool

[rcstevensonaz]

one spare disk eg: da4.nop can't be used as spare of other pool , each spare can be used only in one pool

Curious where that limitation came from. According the the ZFS documentation from Sun/Oracle, they say that spares can belong to multiple pools and provide examples showing that.

I thought at the ZFS level, behavior was standardized across the systems. So I am curious if this is a NAS4Free limitation or a FreeBSD limitation.

[raulfg3]

Sorry, perhaps I'm wrong.

I open a private debate with Michel ,To know if really are limits or not. I edit my answer acording his answer.

PD: i don't have spare disk , and I can't test if works as I described or not.

[rcstevensonaz]

I open a private debate with Michel ,To know if really are limits or not. I edit my answer acording his answer.

Thanks; looking forward to hearing back. It is quite possible that this is a limitation of the GUI and not the underlying ZFS architecture — for example, I would need to manually add spares at SSH level but it can be done. However, I do worry about doing things at low level that will create problems for the upper level GUI.

[misterredman]

I tried in a virtual machine and it is possible to add a spare to multiple pools, but I encountered a strange behavior in the webGUI which I was not able to understand completely.

First time I added the spare after creating both pools and it worked without problems.

Second time I created pool A, added the spare, then created pool B and could not add the spare (the drop down menu was empty). I was able to add the spare to pool B by first removing it from pool A and re-adding it to both.

Similarly to remove it from both pool: no menu item for one pool until I removed the spare from the other.

[cancerman]

Wow, I hadn't thought of this at all. Could the spare be a different size than one of the pools? Eg; RAIDZ1 with 1TB drives and RAIDZ1 with 2TB drives and a single 2TB global hot spare. That would be a great addition. I didn't think to look for it since it's not available in the gui. As we all know, MTBF goes way up with a hot spare.

[misterredman]

Wow, I hadn't thought of this at all. Could the spare be a different size than one of the pools? Eg; RAIDZ1 with 1TB drives and RAIDZ1 with 2TB drives and a single 2TB global hot spare. That would be a great addition. I didn't think to look for it since it's not available in the gui. As we all know, MTBF goes way up with a hot spare.

You can do it as long as the spare is of the same size or bigger than one of the disks it is supposed to replace in case of failure. (it seems it is allowed to add a smaller spare but the replacement will fail when the spare is activated http://docs.oracle.com/cd/E19082-01/817 ... index.html ).

It's also available in the webGUI as far as I can see. Remember to first add the spare as a vdev.