Last Monday, at an event in San Francisco, Steve Ballmer introduced the new, modern Office to the world. An exciting set of capabilities were showcased, including Windows 8 integration, Office as a...
Updated Jul 01, 2019
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It's interesting how the world seems to come full circle.
In Exchange 5.5, it had a single store with 2 databases (Priv and Pub) and the logs were included, and seperate servers that rendered the OWA interface and grabbed the data from the back-end databases.
In Exchange 2003 (I am lumping in Exchange 2000 as well), it moved to a model where you could have multiple databases (each broken into two files, the EDB and the STM file) in each store instance (now referred to as a Storage Group), but the log files were shared amongst multiple databases within the storage group. Additionally the backend database servers switched to using the SMTP on the same backend server to route email to the appropriate databases (even if they were local - but they were processed slightly different than the emails sent to another server), and the Front-End servers were nothing more than proxy servers to the backend database servers where the OWA content was rendered.
In Exchange 2007, it moved back to a model where there was a single private mailbox database to log file relationship in a storage group, and the OWA rendering and mail retrieval functionality moved back to the web server (now called the CAS). Additionally the mail routing moved off of the database server role into a dedicated role (which could optionally be installed on the same server) called the HTS.
In Exchange 2010, the server roles stayed pretty much the same as Exchange 2007, however the back-end databases moved from an Active/Passive 2 node CCR failover model to a truly distributed multi-node multi-copy database cluster known as the DAG.
In Exchange 2013, the roles are moving back to the model where we have the back-end mailbox servers being the ones responsible for routing email, and the CASs are just pass through devices to the back-end mailbox servers who are the ones that actually generate the content.
I just find it interesting/funny that 2007 was a return to 5.5 in some high level respects, and that 2013 is a return to 2003 in some respects.
I can't wait to see what Exchange 2016 has in store for us. :-)