I have been reading about hot spares and would like to add them to my main and backup pools (I am pretty sure I have the hardware to support this). My main pool is RAIDZ2 | 8 wide and my backup is RAIDZ1 | 4 wide. I have been experimenting with creating a new pool (Test) and I have the ability to create a data VDEV and a Spare VDEV … here is a screen shot.
Next … I trashed the Test pool and recreated it with just a mirrored data VDEV. After creating the pool, I added a spare VDEV. The pic of the VDEVs was exactly the same as above.
So … Q: Is the end result (data VDEV and Spare VDEV) the same if I create the spare when I create the pool or add the spare afterwards?
One note, you can SHARE a single hot spare between 2 pools. Of course, the hot spare device has to be large enough for any device in either pool.
But, if the hot spare comes into use, their are problems with exporting the pools. Nothing serious, if exporting either pool, you just have to remove the hot spare from the pool(s) not using it. Then you can export any pool just fine. A little bit of manual effort IF exporting a pool with shared hot spare(s).
Last, Hot Spare vDev(s) are ones that can be added or removed at any time. (Well, when not in use…) Unlike some other vDev types, like data or Special Allocation Class devices.
