RAID Rebuild Started: When to Stop and Evaluate
A rebuild is a normal redundancy operation when one member has failed and every required source read is trustworthy. It becomes risky when the failure history is unclear, another member is unstable, or the rebuild began after the wrong drive was selected.
If the rebuild is stalled, producing read errors, dropping another member, or making the volume unavailable, stop and evaluate before restarting it.
What this condition means
The controller reads the surviving members and writes reconstructed blocks to the target. It does not create a protected copy first, and it may not distinguish an isolated bad sector from broader source instability.
A healthy, progressing rebuild can be appropriate. The warning signs are changing member status, repeated retries, abnormal noise, increasing errors, lost access, or a rebuild that repeatedly stops at the same point.
What to record
- Which member failed and which drive is the rebuild target
- Start time, current percentage, and rate of progress
- Controller event log and read-error counts
- Any new degraded, foreign, or missing status
- Whether applications or databases remain active on the volume
What not to do
- Power-cycle solely to restart progress
- Remove the target or another member without recording state
- Begin a second rebuild on a different target
- Run consistency checks concurrently
- Continue production writes when the array is unstable
How ADR evaluates it
ADR reviews the rebuild state and member health to determine whether the operation should continue, be stopped, or be replaced with protected imaging. That decision is based on evidence, not a fixed percentage threshold.
If the rebuild has already changed the array, both the original members and target may contribute to reconstruction. They are evaluated as separate evidence sources.
ADR can review progress, errors, member health, and the event sequence before the controller is asked to continue. If the rebuild is exposing another failure, the original members and target can be preserved and evaluated separately.
What happens next
The safest action depends on whether the rebuild is healthy or exposing a second failure. A technician review is warranted when progress or member status is abnormal.