One of the goals of Exchange 2010 mailbox resiliency is to minimize data loss. In Exchange 2010 SP1 we added continuous replication block mode to help further reduce data loss when a failover occurs. However, on a very busy mailbox database with a high log generation rate, there is a greater chance for data loss if replication to the passive database copies cannot keep up with log generation.
About The Author
Anderson Patricio is a Canadian MVP in Cloud and Datacenter Management, and Office Server and Services, besides of the Microsoft Award he also holds a Solutions Master (MCSM) in Exchange, CISSP and several other certifications. Anderson contributes to the Microsoft Community with articles, tutorials, blog posts, twitter, forums and book reviews. He is a regular contributor here at Techgenix.com, MSExchange.org, ITPROCentral.com and Anderson Patricio.org (Portuguese).