Mistake. Enlarging ZFS Pool with one Drive but store no data

[Meisterlampe]

Hello,
I have long time runing a ZFS pool of 4x3 TB disks and would like to enlarge the pool by 4 x 2TB disk.
But I went wrong an add a single disk as stripe to the pool.
I did not store any data to the pool until this mistake.
So question is:
Is it possible to delete the single disk stripe?
Or to change them to mirror state by the other three?

Best regards,

Meisterlampe

 

[gpsguy]

Sorry, you can't delete the striped disk, now that it's been added to the pool. And, as you probably know, if this single disk were to fail, you'd lose your volume.

And, you can't change the existing vdev that contains the 4x3TB drives.

At this point, the best solution would be to back up your data and recreate your volume. You could mitigate the risk by adding another disk and mirroring it with the single disk. You'd need to do that from the command line. If you search the forum, you can find the commands to do that.

 

[danb35]

I don't understand how these mistakes continue to happen when big bold red warning text tells you you're doing something you probably don't want to do, and you have to switch into manual mode to do it at all--but people are still persistent enough in doing the wrong thing that it happens.

 

[Meisterlampe]

@gpsguy: Thank you for the reminder of loosing data if the stripe disk went wrong. I will look at the forum for changing it with a mirror disk intermediate before i will redesign the pool. But what will be the best setup with 4x3TB and 4x2TB disks?

@danb35: You are totally right, it was in idiot task to do by the manual mode. But I have seen in another thread that it is not ideal to have different size HDDs but possible. But I could not accept in the automated Mode the setting therefore I changed to manual mode and there I selected only one drive and erroneously stripe not mirror. However idiot behavior has to be punished with a rebuild of the pool.

@both: Thanks for your fast reply.

 

[gpsguy]

It depends on your needs. For block storage, like iSCSI, striped mirrors offer the best performance.

For general use, we recommend RAIDz2. I'd be tempted to go with all 8 disks in RAIDz2. The downside, is that your 3TB drives, effectively become 2TB drives. On the flip side, your pool can withstand the loss of any two drives. Down the road, if you replace the 2TB drives with 3TB drives, your pool size will automatically expand.

But what will be the best setup with 4x3TB and 4x2TB disks?