Exchange Queue Length

Exchange Queue length indicates two types of exchange database log file queues

• Copy queue length (logs) - (CQL)  Indicates the number of log files waiting to be copied and inspected.
• Replay queue length (logs) - (RQL)  Indicates the number of log files waiting to be replayed into this copy of the database.

During regular operations, the Microsoft Exchange Information Store service (store.exe) and the Microsoft Exchange Replication service (msexchangerepl.exe) on DAG members hosting an active database copy write two values to the cluster registry at HKLM\Cluster\ExchangeActiveManager\LastLog:

• DatabaseGUID with a decimal value representing the last log generated by the active copy
• DatabaseGUID_TIME with the system time of when that log file was generated 
   
  These values are written to the cluster registry on the server hosting the active copy, and native cluster registry replication is used to propagate this information to all other DAG members. DAG members that host a passive copy of the database use this information (the last log file generated by the active copy) along with information about the last log file replicated to the passive copy, to determine the CQL for the database copy. Thus, it is critical that all DAG members have up-to-date values, as the CQL is used by Active Manager to evaluating whether or not to mount a database in response to a failover.
  
  If replay queue length is greater than 6 then  EMC database switchover will fail in the replay lag check you need to perform switchover from command line in this case
  
  This example performs a switchover of the database DB4 to the Mailbox server MBX5. In this example, the database copy on MBX5 has a replay queue greater than 6
  
  

  Move-ActiveMailboxDatabase DB4 MBX5 -SkipLagChecks

  In this example, a copy of the database DB4 hosted on MBX3 is activated and mounted as the new active mailbox database. This command makes DB4 the new active mailbox database and it doesn't override the database mount dial settings on MBX3.
  

  Move-ActiveMailboxDatabase DB4 -ActivateOnServer MBX3 

  -MountDialOverride:None
  

  
  This example performs a switchover of the database DB2 to the Mailbox server MBX1. When the command completes, MBX1 hosts the active copy of DB2. Because the MountDialOverride parameter is set to None, MBX1 mounts the database using its own defined database auto mount dial settings.
  

  Move-ActiveMailboxDatabase DB2 -ActivateOnServer MBX1 -MountDialOverride:None
  

  This example performs a switchover of the database DB1 to the Mailbox server MBX3. When the command completes, MBX3 hosts the active copy of DB1. Because the MountDialOverride parameter is specified with a value of Good Availability, MBX3 mounts the database using a database auto mount dial setting of GoodAvailability.
  

  Move-ActiveMailboxDatabase DB1 -ActivateOnServer MBX3 

  -MountDialOverride:GoodAvailability
  

  
  This example performs a switchover of the database DB3 to the Mailbox server MBX4. When the command completes, MBX4 hosts the active copy of DB3. Because the MountDialOverride parameter isn't specified, MBX4 mounts the database using a database auto mount dial setting of Lossless.
  

  Move-ActiveMailboxDatabase DB3 -ActivateOnServer MBX4
  

  
  This example performs a server switchover for the Mailbox server MBX1. All active mailbox database copies on MBX1 will be activated on one or more other Mailbox servers with healthy copies of the active databases on MBX1.
  

  Move-ActiveMailboxDatabase -Server MBX1
  

  
  
  This example performs a switchover of the database DB5 to the Mailbox server MBX6. In this example, the database copy on MBX6 has a ContentIndexState of Failed. As a result, the SkipClientExperienceChecks parameter must be specified to activate the database copy on MBX6.
  

  Move-ActiveMailboxDatabase DB5 MBX6 -SkipClientExperienceChecks