Lagged Mailbox Database Copy is not new , introduced in Exchange 2007using Standby Continuous Replication (SCR).
When using DAG in Exchange 2010 , You can configure the replay lag time and a truncation lag time for Mailbox database copies .
Setting a replay lag time enables you to take a database copy back to a specific point in time. Setting a truncation lag timeenables you to use the logs on a passive database copy to recover from the loss of log files on the active database copy.
Replay lag time is a property of a mailbox database copy that specifies the amount of time, in minutes, to delay log replay for the database copy. The replay lag timer starts when a log file has been replicated to the passive copy and has successfully passed inspection. By delaying the replay of logs to the database copy, you have the capability to recover the database to a specific point in time in the past.
Some findings :
· the replay lag time is an administrator-configured value, and by default, it's disabled.
· The replay lag time setting has a default setting of 0 days, and a maximum setting of 14 days.
· Lagged copies are designed to prevent loss of data in the case of DB corruption.
· corruption case in exchange 2010 is very rare to happen , Exchange 2010 use some protection mechanism to prevent from DB corruption
Truncation Lag Time is a property of a mailbox database copy that specifies the amount of time, in minutes, to delay log deletion for the database copy after the log file has been replayed into the database copy. The truncation lag timer starts when a log file has been replicated to the passive copy, and successfully passed inspection, and has been successfully replayed into the copy of the database. By delaying the truncation of log files from the database copy, you have the capability to recover from failures that affect the log files for the active copy of the database.
Source: http://technet.microsoft.com/en-us/library/dd335158.aspx
To Activate a Lagged Mailbox Database Copy : http://technet.microsoft.com/en-us/library/dd979786.aspx
Posted 04-10-2010 11:59 AM by Samer AlOtaiby
Filed under: Lagged Mailbox Database Copy
