Why is a dedicated server slower during RAID recovery or rebuild?
Rebuild or recovery reads and writes substantial data while the array may have reduced redundancy. That work competes with application I/O, so latency and throughput can change. The duration depends on device size, errors, workload, controller policy and the recovery operation; a single progress estimate is not a completion guarantee.
Before you start
- Authorised access to the dedicated server and the named inspection tools.
Instructions
1. Inspect the recovery state
On Linux md, read the current operation and progress. Hardware-controller rebuilds need the controller’s supported status view.
cat /proc/mdstatDistinguish recovery, resync, reshape and checking operations. They have different purposes and should not be interrupted casually.
2. Measure the application’s storage impact
Collect bounded interval statistics and application latency during the same period. Identify whether critical workload can be reduced or moved through an approved procedure.
iostat -xz 1 5Use queue and latency evidence rather than only utilisation. Review the first report’s since-boot semantics before comparing the sampled intervals.
Check the result
- The rebuild completes to the expected healthy state, no new drive errors appear and application performance returns to the measured baseline.
Troubleshooting
- The completion estimate keeps changing
- Live workload and error handling affect throughput. Use trends rather than promising an exact finish time.
- Lowering rebuild speed is proposed
- It may improve application latency but extend reduced-redundancy exposure. Balance both risks with the storage owner.
- Another member reports errors
- Escalate promptly before attempting additional removals or forced actions.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.