Sitting here in our Disaster Recovery class at SQL Connections and Kimberly’s on till lunch so I’m banging out a quick blog post covering the database mirroring (DBM) specific questions.
Q1) Can I use IP addresses instead of server names when using the DBM Monitor?
A1) Unfortunately not.
Q2) Is there any in-built throttling mechanism in DBM to allow the mirror to catch-up when synchronizing a synchronous mirroring session?
A2) Yes, if there’s more than 1MB of transaction log on the principal that hasn’t been sent to the mirror, the mirroring session state will be switched from SYNCHRONIZED to SYNCHRONIZING and the principal itself will start adding a few milliseconds delay to transaction commits until the amount of unsent log drops below 1MB
Q3) Are there any tips when setting up a mirroring session using backups?
A3) Yes, make sure that all the backups are restored WITH NORECOVERY on the mirror. The database has to be unrecovered otherwise the mirroring session cannot start and you’re back to square one with restoring the mirror database.
Q4) What are the performance considerations with DBM – both in terms of the impact on the application workload and on DBM itself?
A4) Here are some links to resources that discuss this:
- Whitepaper: Database Mirroring: Best Practices and Performance Considerations
- Whitepaper: Database Mirroring: Alerting on Database Mirroring Events
- MSDN webcast – look at Sessions 8 and 9: TechNet Webcast Series for the ITPro – Series Links
Q5) Any other resources?
A5) Blog posts…
- SQL Server 2008: Automatic Page Repair with Database Mirroring
- Search Engine Q&A #2: Moving a database while Database Mirroring is running
- SQL Server 2008: New Performance Counters for Database Mirroring
- Search Engine Q&A #3: Database mirroring failover types and partner timeouts
- SQL Server 2008: Performance boost for Database Mirroring
- More on Database Mirroring performance and index maintenance
- Search Engine Q&A #8: How can defragging an index break synchronous mirroring? And what happens?