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You can open the Mirroring view of the SQL Diagnostic Manager Databases tab by selecting the appropriate SQL Server instance, and then clicking Databases > Mirroring.
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The duration of a mirroring failover operation varies according to the amount of log in the redo queue on the mirror. All transactions in the redo queue must roll forward before the mirror can assume the role of Principal. After the failover is initiated, the Principal changes to PENDING_FAILOVER while the mirror synchronizes. Once complete, there is a brief period where user connections are terminated and while roles are switching the mirroring status is undetermined. If a refresh occurs at this time, your mirrored database does not show in the Mirrored Databases grid. This lasts for a moment and your next refresh reflects the switched roles.
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Suspend or Resume Monitoring
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Available alerts for mirrored databases
You can configure the following alerts for mirrored databases .
Mirror Commit Overhead
Average delay (in milliseconds) on the principal server instance for each transaction due to database mirroring.
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If a witness is configured, this alert displays whether the witness is connected.