How do I add a new disk to an existing mirror vdev, and then remove one existing drive?

[thalf]

Hi,

I'm running TrueNAS-12.0-U8 and want to swap a disk in my 2-disk mirror pool (called pool0). But I'm unsure how to do it.

Is it as easy as going to Storage / Pools / Pool Status in the GUI, clicking the three vertical dots to the right in the MIRROR row under pool0, selecting Extend to get the Extend Vdev pop-up dialog, selecting a new fresh disk I've installed in the NAS (and spent the past >10 days running SMART tests and badblocks on) from the drop-down menu, and then clicking the blue EXTEND button and the (re)silvering will start?

And then, when the new disk is part of the vdev, can I just go to Storage / Pools / Pool Status in the GUI, click the three vertical dots to the right of the disk I want to remove, and select... what? Detach? Or Offline? I'm thinking Detach but I'm unsure.

I'm not used to the TrueNAS terminology, I've just used FreeNAS/TrueNAS for the past 8 years and it's mostly been working so well that I haven't had to dig into it and learn the details. Unfortunately (or not).

 

[Etorix]

Yes, it is as simple as the procedure you describe.
Actually, it is even simpler: Rather than "Extend", select… "Replace".

 

[thalf]

Thanks. If I select Replace, will I at any time just have one disk in the vdev? Or will the new disk be fully silvered in before the old disk is removed from the vdev? Yes, backups, I know... but I don't have any at the moment.

 

[Etorix]

Not having backups is a bad idea. Making changes on a NAS without any backup is an even worse idea.
But "Replace "will temporarily extend the mirror, resilver, and then offline the old drive. It is as safe as performing the procedure step by step as originally outlined.