Continuous Replication Circular Logging (CRCL)

One of my colleagues “ToVe” came up with some interesting details about combining circular logging and continuous replication while working on a Big Bang GroupWise-to-Exchange migration. As I’ve never seen a blog post about it so I’ll have a go at it:

You can combine circular logging with continuous replication. In this configuration, you have a new type of circular logging called continuous replication circular logging (CRCL), which is different from the ESE circular logging described earlier in this topic. Whereas ESE circular logging is performed and managed by the Microsoft Exchange Information Store service, CRCL is performed and managed by the Microsoft Exchange Replication Service.

When enabled, ESE circular logging does not generate additional log files and instead overwrites the current log file when needed. However, in a continuous replication environment, log files are needed for log shipping and replay. As a result, when you enable CRCL, the current log file is not overwritten and closed log files are generated for the log shipping and replay process. Specifically, the Microsoft Exchange Replication Service manages CRCL so that log continuity is maintained, and logs are not deleted by the log deleter if they are still needed for replication. Therefore, enabling CRCL should not negatively affect replication.

more info: http://technet.microsoft.com/en-us/library/bb331951(EXCHG.80).aspx