Help! Pool with 6 vdev mirrored, lost one mirror on disk faulty replacement.

[Alexandre Trevizoli]

Hi all.
I'm using freenas and now truenas for last 7 years, and I try to study a lot about ZFS.
But we never know everything..
I have an customer that have one drive faulted on one of 6 vdev mirrored on pool.
He told me that did normal procedure, did faulted offline and exchange drive and tried to do replacement. Everything on GUI.
They are using truenas 12.
But something happens wrong that mirror disappear, and the non faulted drive stay out of mirror, and new drive not appear on pool.
I can see it if I try to add new vdev so it's available but I don't know why mirror configuration are lost.
This storage have a lot of virtual machines data have backup but not virtual machines (windows, Linux, etc)
If someone can help us to recover I will be thankful.
I know that losing an vdev in a pool is an death sentence, but only one drive was faulted.

 

[Samuel Tai]

If the replacement drive had an existing GPT partition table, it wouldn't have been accepted as a replacement. Unfortunately, the only recovery in this case is to destroy the pool, remove the faulty drive, replace both drives, and reconstruct the pool. Then reload from backup.