Moving disks around: Two questions

[nycvelo]

Greetings. I have two questions about disk upgrades to an existing TrueNAS system:

1. How to relocate a disk from one bay to another in an 4-disk raidz1 pool?

Backstory: A disk previously failed in bay 2 of this 8-bay system. The remote-hands service at my data center put the replacement disk in bay 6. Everything is resilvered and back up and running again, but I want to make room in bays 4-7 for a new raidz2 pool. Can I safely power down the system, relocate the new drive from bay 6 to bay 2 and resilver again? Or something else?

2. I'm looking to migrate my boot pool from two mirrored USB sticks to two NVMe SSDs. (Aside: Just because USB boot sticks work it doesn't mean you should use them, unless you like painfully slow upgrades and anything else involving operating system I/O.)

This older thread suggests the best way to do this is temporarily enable autoexpanding the pool and resilvering:

SOLVED - Boot Vol upgrade: autoexpand?

I currently have mirrored USB sticks for my boot volume. I just ordered 2 DOM's to replace the USB's. In order to keep my previous boot volumes, I would like to add the 2 DOM's to the Boot volume, and then remove the 2 USB's. Since the DOM's are larger than the USB's, what happens to the excess...

www.truenas.com

Is this still considered a best practice?

Thanks!

 

[sretalla]

How to relocate a disk from one bay to another in an 4-disk raidz1 pool?

With the system powered down, move the disks as you please and boot, no need to resilver.

I'm looking to migrate my boot pool from two mirrored USB sticks to two NVMe SSDs.

Watch out for differences in block size/ashift if you're mixing them in a mirror temporarily.

The best way to avoid that would be config backup, reinstall to NVME, restore config.

NVME (let alone 2 of them) is probably excessive performance for boot pool. You may not get what you're expecting in terms of an indestructible boot process unless your BIOS does the mirroring and allows booting/continuous operation from those devices.

 

[rvassar]

With the system powered down, move the disks as you please and boot, no need to resilver.

^^^^^ This.

Yes it's that simple. You can even move between controllers, within reason... Obviously you can't break the boot drive sequence.

The pool components are tracked by a form of UUID. It just ID's the drives and stitches the pool back together at boot time import.