Excellent dox on replacing failed disk/expanding ZFS pool in Freenas

[kappclark]

FWIW - just want to thank the Freenas team for the very clear documentation on replacing a failed disk in a pool ... with so many moving parts in Freenas, this was crystal clear..

I followed instr for FreeNAS-11.3-U2.1 in order to replace 1 T disks with 2T disks in order to expand the pool --- resilvered after each replacement -- Felt like it was going to be surgery, but measure twice cut once... first pair is done, when next 2 disks come in, will do the same

10.5.1. Replacing a Failed Disk

 

[Basil Hendroff]

A word of caution though. If you don't have a reliable backup of your data before starting the process of replacing disks, you could be jeopardising your data as things can go pear-shaped very quickly. You should consider burning in new disks as well. Here's a resource for future reference Hard Drive Burn-in Testing.

I'm aware of a recent incident where a forum member did exactly as you did for a RAIDZ1 pool, but in the process of resilvering a disk, one of the other disks he had just replaced failed. This resulted in a catastrophic failure of his pool - the resilver of one disk and the h/w failure of another disk being equivalent to a two-disk failure. Fortunately, he had a backup of his data, so a complete disaster was avoided. There's a bit more of a safety net with RAIDZ2. The point is though, assume the worst and prepare for it, and you're more likely to be assured of a successful outcome.

 

[kappclark]

Thank you Basil - the 2 disks I used were pulled from a proxmox server, with no errors, but I will def burn in the 2 new iron wolfs which are coming in ...soon I hope.

The backup I had was only a few days days old, so I was happy with that I checked it for a few large files etc ..-- disaster can strike - and we know ransomware is not an urban legend.

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Followup on this -- the 2TB Ironwolfs arrived, and they passed the burn-in testing -- once backup is complete, I will replace with confidence...THX again for the guidance, as always