eG Monitoring
 

Measures reported by XChgReplicationTest

Cluster continuous replication (CCR) is a high availability feature of Microsoft Exchange server 2007/2010 that combines the asynchronous log shipping and replay technology built into Exchange 2007/2010 with the failover and management features provided by the Cluster service.

CCR uses the database failure recovery functionality in Exchange 2007/2010 to enable the continuous and asynchronous updating of a second copy of a database with the changes that have been made to the active copy of the database. During installation of the passive node in a CCR environment, each storage group and its database is copied from the active node to the passive node. This operation is called seeding, and it provides a baseline of the database for replication. After the initial seeding is performed, log copying and replay are performed continuously.

In a CCR environment, the replication capabilities are integrated with the Cluster service to deliver a high availability solution

Local continuous replication (LCR) is a single-server solution that uses built-in asynchronous log shipping and log replay technology to create and maintain a copy of a storage group on a second set of disks that are connected to the same server as the production storage group. The production storage group is referred to as the active copy, and the copy of the storage group maintained on the separate set of disks is referred to as the passive copy.

This test monitors the health of the replication in both LCR and CCR.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Replay_queue_length Indicates the number of log generations currently waiting to be replayed. Number  
Copy_queue_length Indicates the number of log files currently waiting to be copied and inspected. Number A high value of this measure could indicate that Exchange database copy failed. Under such circumstances, do the following:

  • Remove passive DB copy
  • Delete DB and log files from disk
  • Force AD replication between AD sites
  • Dismount AD database
  • Delete all EO*.log files
  • Mount database
  • Create DB copy