SQL Server repair planning
DBCC CHECKDB may recommend REPAIR_ALLOW_DATA_LOSS when it cannot repair corruption without removing pages, rows or structures. Microsoft describes it as an emergency last resort, not an alternative to restoring a known good backup.
Understand the symptom
Emergency repair can deallocate unreadable pages and, if log recovery fails, rebuild the transaction log. The database may open afterward while rows, constraints or transaction relationships are missing, so a clean restore, replica or object-level extraction should be compared first.
What you may see
Reported corruption has no non-lossy built-in repair path.
Normal recovery failed and access is restricted for last-resort work.
Tables, indexes or LOB content were removed to regain consistency.
Structural repair completed but application data is incomplete.
Protect the source
The option name accurately warns that repair may discard data.
There is no full ACID guarantee after emergency log reconstruction.
The repaired database can corrupt again if the I/O path is not fixed.
Do this now
Do not run the command on the only database copy.
Copy all files, backups, keys, logs, error reports and storage snapshots.
Record CHECKDB output, page IDs, allocation units, tables and priority records.
Inventory backups, replicas, page-restore options and application exports before repair.
NEPFOSYS process
NEPFOSYS maps errors to pages, objects, filegroups and storage events.
Restore, extraction and repair paths are evaluated on separate protected copies.
Constraints, row counts and priority business records are checked after recovery.
A clear next step
Start a case with the exact symptoms, incident timeline, prior attempts, encryption details, and the files that matter most. NEPFOSYS will route the case to the appropriate DFW intake or nationwide mail-in path.
Start with a case reviewQuestions, answered
Not every run removes user rows, but it is permitted to deallocate damaged structures and can cause more loss than a clean restore.
No. Application logic, constraints and priority records must also be validated.
A known good restore, healthy replica, page restore or controlled extraction should be evaluated before emergency repair.
DFW local · Nationwide mail-in