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Best Practices of Mirroring


  • The principal database and the mirror database should be on separate physical hardware, and ideally, in different physical locations.
  • The witness server should be on separate physical hardware, and be on a separate network (best if at a third location).
  • Initial database mirroring setup should be done during less busy times, as the setup process can negatively affect performance of the production database being mirrored.
  • Use high availability mode whenever possible, and high performance mode only when required.
  • The hardware, along with the OS and SQL Server configuration, should be identical (at least very similar) between the two servers.
  • While a fast connection is not required between mirrored servers, the faster the connection, and the better quality the connection, the better.
  • You will want to optimize the performance of the mirrored database as much as possible to reduce the overhead caused by the mirroring process itself.
  • Thoroughly test database mirroring before putting it into production.
  • Monitor database mirroring daily to ensure that it is working properly, and is meeting performance goals.
  • Develop a formal operational and recovery procedure (and document) to support mirroring. Periodically test the failover process to ensure that it works.

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