What to do if Rebuilding does not Start when a New Drive is Plugged in degraded mode?

Last modified date: 2026-08-11

Applicable Products

QNAP NAS (QTS, QuTS hero)

Scenario

When a RAID group is in degraded mode, inserting a replacement drive usually starts rebuilding automatically. In some cases, rebuilding does not start because the new drive is not automatically assigned to the degraded RAID group.

Note
This article only applies to RAID in degraded mode (the number of failed drives is still within RAID fault tolerance).
If the RAID is inactive or offline, use the inactive RAID recovery procedure instead.

Prerequisites

Ensure the replacement drive capacity is equal to or larger than each current RAID member drive.
If the new drive is not purchased from a reputable or authorized channel, the drive quality may be unreliable. Verify the drive can operate normally before use.

Solution

Log in to the NAS through a web browser.
Open Storage & Snapshots.
Go to Storage > Storage/Snapshots.
Select the target Storage Pool or Static Volume, and click Manage.
In the degraded RAID group section, click Manage > Configure Spare Disk.
Select the replacement drive, then click Apply.

Expected Result

RAID rebuilding starts immediately.
After rebuilding is complete, the RAID status returns to normal.

Troubleshooting

Issue: The replacement drive cannot be selected as a spare disk.

Checks:

Confirm the drive capacity meets the requirement (equal to or larger than RAID member drives).
Confirm the drive health is normal (no SMART warning, no bad blocks).
Confirm interface and model compatibility with the NAS.

If the problem is not solved, collect system dump logs and contact QNAP Support.