I have TrueNAS core 12 and had a pool of 2 HDDs in mirror mode. The one of the drives started having problems so I decided to replace it before it failed completely.
I tried to follow the steps in the documentation with the hot spare option: offlined, detached the failing drive etc. I must have missed a step as the new drive is showing under “Spares” if I go to Pools->Status. Moreover, no resilvering process has been initiated. So: Is there anything I can do to add the Spare disk to the Mirror?
I have a similar scenario. A drive failed and a spare was pulled in and resilvered. I replaced the failed disk (it resilvered again) and now I see this: