Adding vdev to zpool

[robotlover]

Hey guys,

I'm planning to expand my storage and I'd like to run it by the experts first.

Currently I have 10 x 3TB drives set up in a RAIDZ2 for 24TB usable.

My plan was to add another vdev to this zpool with 8 x 4TB RAIDZ2 for again 24TB usable for a total of 48TB.

Does this sound like a reasonable plan of action?

Is this type of action available in the GUI, or would I be better served from the CLI?

Also, Do you think it will be be okay to only have 32 GB of RAM when I am not using deduplication or any other advanced features?


Thanks,

 

[cyberjock]

You need to add 10 disks at a time when expanding vdevs. So you need to look at 10x4TB in a RAIDZ2 so you keep the same number of spindles per vdev.

 

[danb35]

You need to add 10 disks at a time when expanding vdevs.

"Need to"? It's recommended, no doubt, but there's no such requirement that I've seen.

 

[cyberjock]

"Need to"? It's recommended, no doubt, but there's no such requirement that I've seen.

"recommended" and "required" aren't the same thing. That's like saying we recommend (versus require) you to not add single disks to a zpool that has redundancy. Can you do it from a technical standpoint? Absolutely. Is there a physical limitation that makes it impossible to do? Nope. You can do it, and people used to do it. The WebGUI won't let you do it with the normal zpool manager, but you *can* still add single disks using the manual option in the GUI.

It's recommend so highly that it is effectively a requirement. I'm pretty sure the WebGUI enforces this too.

 

[robotlover]

Thank you for your input.

Guess I'll bite the bullet and purchase 10 drives.

More storage doesn't hurt either ;)

 

[Pheran]

You need to add 10 disks at a time when expanding vdevs. So you need to look at 10x4TB in a RAIDZ2 so you keep the same number of spindles per vdev.

Now I'm really confused. Since when do all vdevs in a pool have to have the same number of drives? I've never heard this before, and I spent bunches of time researching FreeNAS.

 

[cyberjock]

It's been like that for as long as I've been using ZFS....

 

[Pheran]

It's been like that for as long as I've been using ZFS....

OK, now I know why I'm so confused, your own FreeNAS presentation contradicts this (but it does say that the same number of disks is "recommended"). So we're probably just arguing the semantics of "recommended" per your post #4.

 

[cyberjock]

OK, now I know why I'm so confused, your own FreeNAS presentation contradicts this (but it does say that the same number of disks is "recommended"). So we're probably just arguing the semantics of "recommended" per your post #4.

That would be correct.

In theory, you can go from RAIDZ(x) and then add mirrors. But what you shouldn't do is mix RAIDZ(x) with another RAIDZ(x) that isn't the exact same number of disks and exact same RAIDZ(x) as the others. I've actually added some more comments about it in my presentation. It needs updated and I'm planning to release an update this week.

 

[Ericloewe]

That would be correct.

In theory, you can go from RAIDZ(x) and then add mirrors. But what you shouldn't do is mix RAIDZ(x) with another RAIDZ(x) that isn't the exact same number of disks and exact same RAIDZ(x) as the others. I've actually added some more comments about it in my presentation. It needs updated and I'm planning to release an update this week.

Now I'm curious. Why would a slightly different RAIDZ setup be worse as a second vdev than a mirror?

 

[Jailer]

Wondering the same thing here.