Description
For databases using mirroring. This wait type accumulates while SQL Server is waiting for transaction log records to be flushed to disk. High values are expected but if this is experienced along side extended mirror latencies then investigation is required. Please note that database mirroring is a deprecated feature and could be removed in an upcoming release. Investigation into other high availability and disaster recovery solutions is recommended
Resolved by
DBAs and Developers
Suggested solutions
- If transactions on the principal are being delayed (because of high waits) consider switching the mirror mode to asynchronous
- Use Windows Performance Monitor to check network latency and whether the connection is over-utilised
- Ensure network devices have been configured correctly
- Consolidate transactions from row-by-row statements to batch processing. Batch processing generate less messages
- Check the performance of the disks hosting the data and transaction log files
- Unnecessary index maintenance must be sent across to the mirror (unnecessary messages). Remove any unused indexes from the principal
Additional research
Troubleshoot Database Mirroring Configuration
Database Mirroring Best Practices and Performance Considerations?