Continuous Replication operates by shipping copies of the logs created by the active database copy to the passive database copies. With Exchange 2010 SP1, this is known as Continuous Replication -File Mode as the log file is only copied once it is full (1MB)
SP1 introduces a new form of continuous replication known as Continuous Replication – Block Mode. In block mode, when an update is written to the active database log file it is immediately copied to the passive mailbox copies, thus reducing the latency between the time a change is made on the active copy and the time that same change is replicated to a passive copy
To check continuous replication is operating in block mode or file mode,
Get-Counter -ServerName <> -Counter “\MSExchange Replication(*)\Continuous replication – block mode Active”
Output will be
04/09/2012 11:39:46 \\MBX1\\msexchange replication(mdb32)\continuous replication – block mode active : 1
\\ MBX1\\msexchange replication(mdb25)\continuous replication – block mode active : 1
\\ MBX1\\msexchange replication(mdb24)\continuous replication – block mode active : 1
“1” means that block mode is active while a “0” means it is not
In other word,
CRBM and CRFM are 2 new feature’s in Exchange 2010 SP1.Exchange 2007/2010RTM relied on log shipping from an Active node to a Passive one which means, after a 1mb log file is committed onto the active database, it will get shipped to the passive copy.
With the release of SP1, Continuous Replication File Mode (CRFM) and Continuous Replication Block Mode (CRBM) are being introduced.