Resilvering question

[G8One2]

So I've done a quick search and haven't been able to find an answer specific to this. Can anyone tell me, if its ill advised to resilver more than one disk at a time? Currently I have three RaidZ2, six disk vdevs. Each of the three vdevs all have four 4tb disks, and two 2tb disks. I'm looking to expand the pool and replace all six 2tb disks. I think I can safely, resilver 1 disk in each vdev at the same time, so 3 disks resilvering simultaneously . This would leave me one disk in each vdev for redundancy during the resilvering process. Would doing this be a bad idea? Or would it be advisable to just resilver one disk at a time?

 

[Johnny Fartpants]

In my experience resilver is normally based on priority so each disk is done in turn so not much/any merit in resilvering more than one at a time. Do one whichever is deemed more important (if any) and then move onto the next. One at a time.

 

[G8One2]

Awesome! Thank you, I'll do just that

 

[Etorix]

If you have free ports and slots you may resilver as many drives as you want keeping the old drives in place throughout the process. No loss of redundancy.
It's possible that ZFS will still do one drive at a time though.

 

[G8One2]

Yeah I have a 24 disk 4U supermicro. Currently have 18 disks in there, six open and free slots so I could do it that way, but if its only going to do 1 disk at a time, I see no point.

 

[G8One2]

Would adding another vdev, of smaller disks limit the size of the pool to the size of the smallest disks? Im considering making another vdev with the spare 2tb disks, but I dont want to do that if adding a smaller vdev would shrink the pool.

 

[Etorix]

Each vdev is limited by the size of its smallest member, not the pool as a whole.

 

[G8One2]

I thought that was how it worked, wasn't sure though. I'm gonna go ahead and use the other six 2tb disks to create a fourth vdev, nothing was wrong with these disks. I was just getting to 80% capacity warning, needed to expand my pool. Should get me a total storage size of 51.04Tb with all these disks.

 

[Etorix]

The drawback is that you'll fill all slots with drives, and rather small ones. So to further expand there would then be no alternative to replacing the old small drives—one at a time and with an intermediate loss of redundancy.
If you can, get 4 TB drives or larger, and begin replacing the 2 TB drives, vdev by vdev. Keep some free slots for maintenance if possible.