You replaced a failed drive in your TrueNAS system expecting ZFS to rebuild cleanly — but now your volume won’t mount at all.
What’s Really Happening
In ZFS-based systems like TrueNAS, pool health is deeply tied to metadata consistency and vdev integrity. After replacing a drive:
- ZFS may see the new drive as a mismatch to the expected vdev layout
- Pool import errors can occur if metadata is stale or corrupted
- System may boot but volume remains offline due to unrecognized or partially imported pool
What Not To Do
- Don’t force a pool import without checking
zpool statusand logs - Avoid wiping the new drive and reinserting unless advised
- Don’t assume resilvering has failed — it may not have started due to mismatch
When To Escalate
- If
zpool importreturns I/O errors or incomplete pool structures - If the volume disappears or throws checksum/mismatch alerts
- If the replacement drive appears in hardware but not in ZFS
What You Can Do
Jeannie can analyze your current vdev map and tell you:
- Whether a ghosted or detached vdev is blocking mount
- If resilvering is stuck or failed silently
- What pool recovery options are still viable