Recover a SQL Database After RAID 5 Failure
A RAID 5 failure can leave SQL Server offline even after the array or files appear to return. The storage reconstruction and the database must be evaluated as separate recovery layers.
Do not rebuild the RAID or repair the database merely to test it. Preserve every member, the controller history, and the first available database files.
Tell an ADR technician what the system reports and what has already been attempted. The failed system does not have to be brought online first.
What this condition means
RAID 5 protects against one member failure, but unreadable sectors, a second unstable member, interrupted rebuilds, or configuration changes can return incomplete blocks to the filesystem and database files.
SQL Server may then report Recovery Pending, attach failure, page errors, or transaction-log disagreement. Those messages can be the final symptom of an earlier array problem.
What to record
- RAID controller, member count, drive order, and failure sequence
- Rebuild start, stop percentage, replacements, and controller messages
- SQL Server version, database size, and exact errors
- MDF, NDF, LDF, backup, and recovered-file locations
- Priority databases, tables, records, and operational deadlines
What not to do
- Start another RAID rebuild
- Force a member online
- Run filesystem or SQL repair on the only copy
- Restore onto the affected RAID
- Discard original or partial-rebuild members
How ADR evaluates it
ADR protects and reconstructs the RAID 5 member set away from the failed controller, then evaluates the resulting database files from protected copies.
The recovery target is usable business data. Verification follows the required tables and records through the array, filesystem, and database layers.
ADR can begin with the original RAID members, validate the reconstructed volume, and then evaluate the SQL files produced from that state. The controller does not need to rebuild the array and SQL Server does not need to repair the only database copy first.
What happens next
Many RAID 5 database cases remain recoverable when the members and first database copies are preserved. Results depend on readable member coverage, prior writes, and the internal condition of the database files.