Global spare

[poldas]

Hi,

I have 2 Volumes each has 4 SSD 1.9TB - RAIDZ1. I bought one more disk SSD 1.9TB and want to use it like a global spare for both Volumes. Is it possible to use one disk like a spare for two volumes?

 

[Johnny Fartpants]

Depends what you mean by 'volume' but assuming you mean zpool then no. A spare can only be assigned to one zpool. However, if you meant two vdevs in one zpool then yes sure the disk will act as a spare for the whole pool regardless of vdev.

If you did two pools then the question is why?

 

[Chris Moore]

Hi,

I have 2 Volumes each has 4 SSD 1.9TB - RAIDZ1. I bought one more disk SSD 1.9TB and want to use it like a global spare for both Volumes. Is it possible to use one disk like a spare for two volumes?

As Johnny said the question is why, because the configuration you have, if it is two separate pools, is less than optimal.

 

[Arwen]

Yes, hot spares can be shared between pools. Here is an extract from the manual page;

Spares can be shared across multiple pools

 

[Chris Moore]

Yes, hot spares can be shared between pools. Here is an extract from the manual page;

Is two pools the optimal configuration?

 

[Johnny Fartpants]

Yes, hot spares can be shared between pools.

Does that actually work on FreeNAS/FreeBSD?

 

[Arwen]

@Chris Moore, I don't know. I simply knew that spares had been designed for global use, back when ZFS was Solaris mostly/only. But going back to the original posting, it does look like a single pool with 2 vDevs would be better.

@Johnny Fartpants, again I don't know. Simply verified it from the manual page on Linux. But even if that is not a FreeBSD/NAS thing, they are moving the OpenZFS code base to the one shared with Linux.

The issue with spares on FreeBSD/NAS & Linux, is likely more to do with the "zed" daemon. If I recall correctly, that is the creature responsible for activating a spare. (I've not used spares at home, on FreeNAS or Linux. And any ZFS spares I have used, were on Solaris... which handles spare activation differently.)