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Bringing down mirror and witness? RRS feed

  • Question

  • What would be the impact of temporarily bringing down the mirror and witness instance?  Both reside in a datacenter that will be offline for a short period of time?
    Thursday, November 15, 2018 4:34 PM

All replies

  • I take it you are running in high-safety mode with automatic failover. To be on the safe side you should temporarily remove the witness or set safety off and pause mirroring: ref: https://docs.microsoft.com/en-us/sql/database-engine/database-mirroring/quorum-how-a-witness-affects-database-availability-database-mirroring

    The principal databases will be online and accessible. Mirroring will be suspended, and the principal server's mirrored database(s) transaction log files will continue to grow until either mirroring is removed for the mirrored database(s) or the mirror server is brought back online.

    Thursday, November 15, 2018 7:57 PM
  • What would be the impact of temporarily bringing down the mirror and witness instance?  Both reside in a datacenter that will be offline for a short period of time?

    You can temporarily "Pause" mirroring (from the DB properties-->Mirroring-->pause). Doing that will stop sending the transactions to the Mirror DB. After the maintenance is done and the Mirror and Witness are back online, you must tell it to resume from where it left off (again, by going to DB properties-->Mirroring-->Resume). 

    As for the impact, the log on the principal will not truncate until the Mirror joins back potentially causing the log to grow. Hence, it'd be safe to plan the maintenance during after hours or when there's low/no activity. 


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    • Proposed as answer by Teige Gao Monday, November 19, 2018 6:40 AM
    Thursday, November 15, 2018 9:41 PM