There are different ways to monitor database mirroring, based on what information you want to track. For basic information about the database mirroring state, safety level, and witness status, you can use catalog views. Refer to the "Database Mirroring Catalog Views" section earlier in this chapter for more details about catalog views. To monitor the performance of database mirroring, SQL Server 2008 provides a set of System Monitor performance objects. There is also a GUI "Database Mirroring Monitor" available with SQL Server 2008 Management Studio, which you can access if your database is mirrored. We discuss both the key System Monitor counters and the GUI in this section.
The object SQL Server: Database Mirroring has plenty of counters to monitor database mirroring performance. You can use these counters to monitor the database mirroring activities on each partner, and the traffic between them, as shown in Figure 17-6. You can do this for each database instance, so if you are mirroring more than one database on a server, select the database you want to monitor from the list box. The key counters are described in the following sections.
The following System Monitor counters are used on the principal server:
Log Bytes Sent/Sec: The rate at which the principal is sending transaction log data to the mirror
Log Send Queue KB: The total kilobytes of the log that have ...