Help extending a pool

[Berkyjay]

I have 2 unused 6TB HDDs that I want to add to my current pool. I've done this in the past with 3 new HDDs but it's been a while since I've attempted this and I really don't want to mess things up. So I'm hoping someone could give me some guidance. Here's a screen grab of my current pool status. Thanks in advance.

 

[danb35]

There really isn't going to be a good way to add two disks to this pool. You could add them as a mirrored vdev, but it's preferred that all vdevs in a pool match in number of disks, type, and ideally size of disks. If you can get a third disk and have room for all of them in your case, that would be better.

 

[Berkyjay]

Ugh, that's what I was afraid of. I just spent a lot of money, time, and effort upgrading my rig to use all 8 HDD slots in my case. But when I want to add the two new HDDs I started to see that this might not be possible with my current configuration. I guess I'm going to go with plan be and back everything up and redo my entire pool. :/

That would leave me with five 6TB and three 4TB HDDs. Any advice on how to approach configuring a new pool with those?

 

[danb35]

That would leave me with five 6TB and three 4TB HDDs. Any advice on how to approach configuring a new pool with those?

Best I could say would two four-disk RAIDZ vdevs, but we really don't like RAIDZ1 with disks > 1 TB.

 

[Berkyjay]

but we really don't like RAIDZ1 with disks > 1 TB

Why is that?

Never mind, I found this link that gives me some insight.

 

[TAC]

There really isn't going to be a good way to add two disks to this pool. You could add them as a mirrored vdev, but it's preferred that all vdevs in a pool match in number of disks, type, and ideally size of disks. If you can get a third disk and have room for all of them in your case, that would be better.

@danb35 What's the downside of not matching the size of the disks in two vdevs? I currently have a 6 drive, 4TB, RAIDZ2 vdev in a pool and I'm planning on extending that pool with six 6TB drives.

 

[sretalla]

What's the downside of not matching the size of the disks in two vdevs? I currently have a 6 drive, 4TB, RAIDZ2 vdev in a pool and I'm planning on extending that pool with six 6TB drives.

If the intent is to have 2 VDEVs for the additional IO, then a mis-match in size will defeat that at some point.

If you expand an existing/partially filled pool, you will probably suffer that already as the writes will all go to the new VDEV for a while until things even out.

If you want to avoid that, you need to rebuild the pool as 2 VDEVs and re-fill it from backup to get it balanced.

 

[TAC]

If the intent is to have 2 VDEVs for the additional IO, then a mis-match in size will defeat that at some point.

If you expand an existing/partially filled pool, you will probably suffer that already as the writes will all go to the new VDEV for a while until things even out.

If you want to avoid that, you need to rebuild the pool as 2 VDEVs and re-fill it from backup to get it balanced.

Just looking for some additional TBs for my media library. :)

@sretalla if I copied a bunch of files to a temp directory and then back would this tend to even things out between the vdevs?

 

[HoneyBadger]

Just looking for some additional TBs for my media library. :)

If performance isn't a major concern then it's not likely to impact you, outside of doing very large copies.

@sretalla if I copied a bunch of files to a temp directory and then back would this tend to even things out between the vdevs?

Provided that temp directory is outside the pool in question, yes.

 

[stlkr]

Hi,
I need help because I added a new 2TB in my NAS. My intention is mirror my first disk. But I merged the pool accidently. So, now I have 4TB and just ‘one disk’. Can I revert this process to the original and had agiam two disks instead a merged disk? Thanks

 

[danb35]

Can I revert this process to the original and had agiam two disks instead a merged disk?

You can, but you'll need to do it at the CLI. What's the output of zpool status?

 

[stlkr]

You can, but you'll need to do it at the CLI. What's the output of zpool status?

Ok. It’s fine for me. My output is

 

[danb35]

So to remove the second disk, you'd run zpool remove Disco1 gptid/blah, where "blah" is the identifier of your second disk (which I can't copy/paste from a screen shot). Allow that to complete (which you can monitor with zpool status), and then you can remove the second disk. You can't add it to your pool as a mirror through the GUI--despite an outstanding feature request for over five years, the devs haven't bothered to add that feature. You can, however, do that through the GUI CLI; there are other threads here with instructions.

 

[stlkr]

So to remove the second disk, you'd run zpool remove Disco1 gptid/blah, where "blah" is the identifier of your second disk (which I can't copy/paste from a screen shot). Allow that to complete (which you can monitor with zpool status), and then you can remove the second disk. You can't add it to your pool as a mirror through the GUI--despite an outstanding feature request for over five years, the devs haven't bothered to add that feature. You can, however, do that through the GUI; there are other threads here with instructions.

It works. Thank you so much. I will investigate a tutorial to implement the mirror in my second disk.

 

[sretalla]

You can, however, do that through the GUI; there are other threads here with instructions.

You probably meant CLI there...

 

[danb35]

You probably meant CLI there...

Oops, you're right--fixed.