Returns information about warning thresholds on one or all of several key database mirroring monitor performance metrics.
Specifies the database.
- [ alert_id ]
An integer value that identifies the warning to be returned. If this argument is omitted, all the warnings are returned, but not the retention period.
To return a specific warning, specify one of the following values:
Value Performance metric Warning threshold
Oldest unsent transaction
Specifies the number of minutes worth of transactions that can accumulate in the send queue before a warning is generated on the principal server instance. This warning helps measure the potential for data loss in terms of time, and it is particularly relevant for high-performance mode. However, the warning is also relevant for high-safety mode when mirroring is paused or suspended because the partners become disconnected.
Specifies how many kilobytes (KB) of unsent log generate a warning on the principal server instance. This warning helps measure the potential for data loss in terms of KB, and it is particularly relevant for high-performance mode. However, the warning is also relevant for high-safety mode when mirroring is paused or suspended because the partners become disconnected.
Specifies how many KB of unrestored log generate a warning on the mirror server instance. This warning helps measure failover time. Failover time consists mainly of the time that the former mirror server requires to roll forward any log remaining in its redo queue, plus a short additional time.
Mirror commit overhead
Specifies the number of milliseconds of average delay per transaction that are tolerated before a warning is generated on the principal server. This delay is the amount of overhead incurred while the principal server instance waits for the mirror server instance to write the transaction's log record into the redo queue. This value is relevant only in high-safety mode.
Metadata that controls how long rows in the database mirroring status table are preserved.
For information about the event IDs corresponding to the warnings, see Using Warning Thresholds and Alerts on Mirroring Performance Metrics.
For each returned alert, returns a row containing the following columns:
The following table lists the alert_id value for each performance metric and the unit of measurement of the metric displayed in the sp_dbmmonitorresults result set:
The threshold value for the warning. If a value above this threshold is returned when the mirroring status is updated, an entry is entered into the Windows event log. This value represents KB, minutes, or milliseconds, depending on the warning. If the threshold is currently not set, the value is NULL.
0 = Event is disabled.
1 = Event is enabled.
The following example returns a row that indicates whether a warning is enabled for the oldest unsent transaction performance metric on the AdventureWorks database.
EXEC sp_dbmmonitorhelpalert AdventureWorks, 1 ;
The following example returns a row for each performance metric that indicates whether it is enabled on the AdventureWorks database.
EXEC sp_dbmmonitorhelpalert AdventureWorks;