The RAID Controller Failed or Was Replaced, and the SQL Database Is Still Unavailable
The drives may still identify and a replacement controller may even present a virtual disk, yet SQL Server will not start, attach, recover, or trust the production database. The urgent question is whether the controller reproduced the same array state the database used before the failure.
Do not initialize, recreate, import, clear foreign metadata, force members online, or repair SQL on an unvalidated volume. Preserve every original member, controller record, replacement state, and database-file version.
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
The controller decides which members belong to the virtual disk and how their blocks are presented. A failed controller, replacement, import, or recreated configuration can select a different member set, geometry, or array generation while still returning normal-looking files.
SQL attach, recovery, or consistency errors after controller work may therefore be the final symptom of a storage-presentation problem. A visible volume or correctly sized MDF does not prove that the underlying blocks match the original database state.
What to record
- Original and replacement controller models, firmware, cache, and configuration records
- Physical-member and virtual-disk status before and after the failure or replacement
- Original bay, slot, serial number, capacity, and present status of every drive
- Database paths, versions, sizes, timestamps, states, and exact SQL errors
- Imports, clears, recreations, forced-online actions, rebuilds, restores, attaches, and repairs already attempted
- The application, tables, dates, and business records required first
What not to do
- Initialize or recreate the array from remembered settings
- Clear or import foreign metadata before documenting the complete member set
- Force members online to test combinations
- Start a rebuild to see whether the database returns
- Run SQL repair on files from an unvalidated volume
- Overwrite the first recovered database files with a restore or repaired copy
How ADR evaluates it
ADR removes the failed controller from the recovery decision when it cannot present a trustworthy array. Member identity, stability, metadata, order, offsets, stripe geometry, and parity behavior can be evaluated independently.
Only after the storage state is validated does ADR examine protected database copies. Candidate results are checked against the tables, dates, relationships, and application records the business actually needs.
ADR can begin with independently connected RAID members, reconstruct and validate the storage outside the failed controller, and then evaluate the database files from protected copies. The production server and replacement controller do not have to become the recovery environment.
What happens next
Controller failure does not establish that the database is lost. The result depends on member readability, the states presented before and after controller work, prior writes and rebuild activity, and the internal consistency of the database files recovered from the defensible array state.