Single drive pool to mirror

[TomW51]

Hi, I'm new here and not good with understanding some of the answers, so please bare with me. I'm running Freenas 11.3-U5 now, and have 3 single disk pools NAS1, NAS2, NAS3 for Movies, Concerts, and Music. The disks are 2TB, 2TB, 1TB. My nas1 is full and this is what I would like to do. Add 4TB disk to mirror Nas1 then replace 2TB disk with another 4TB, then after take 2TB disk and mirror Nas2. After reading some other posts about this it seems I can do this in Truenas12 by using extend, but after reading posts about not being able to access smb shares after upgrading I'd prefer not to do this right now. I then looked in 11.3 and extend is there too. Is this the same, and can I do what I want in 11.3-U5? If not with GUI can it be done with command line?
Thanks for any help, Tom

 

[NugentS]

You can add a 4TB to a 2TB as a mirror, resilver and then replace the old 2TB with another 4TB and resilver again. At this point the pool should extend automatically to 4TB
[Caveat: I am not familiar with TN 11.x] but the theory is sound. There should be no issues doing that - its standard practise

 

[TomW51]

OK. Sorry this took so long, but between other projects I decided to upgrade to 12.0-U8. All went without any problems, so now I'm going to try adding the disks and just want to make sure I've got the steps right. I have not upgraded the pools yet, but if I have to before I proceed let me know. The new 4TB disks are in and show up as da1 and da2. So from dash choose NAS1 status, click 3dots pick extend, from extend vdev new disk pick da1, then click extend. This will create a single vdev with 2 disks that are mirrored? Also is anything I should do with the new disks before starting?