by Marquis Calmes
24. August 2009 19:13
Last week Microsoft published the first release candidate of the new Exchange Server 2010. This is one of the final milestones in the roadmap for final release early next year. As with any new update the biggest question is what is in the upgrade that makes the expense and hassle of an upgrade worthwhile. This is especially true for users that have recently upgraded to Exchange 2007. I’m pleased to say that while there are numerous improvements in Exchange 2010, there are several that standout and make a compelling argument for upgrade.
At the top of the list are the improvements made for high availability. Exchange 2007 offered a number of different high availability (HA) options (SCR, CCR, and SCC). Standby Continuous Replication offered relatively inexpensive DR functionality for Exchange, but failover was a manual process. CCR, or Cluster Continuous Replication, and SCC, or Single Copy Cluster, allowed for automatic failover within a single site but required installing only the mailbox role inside the cluster. This meant a minimum of three Exchange licenses to achieve high availability, four if you wanted redundancy for the other Exchange roles. In addition to that expense, the configuration was a very manual process that required a great deal of time.
In Exchange 2010, Microsoft has eliminated many of the prior HA configuration in favor of a new concept called database availability groups (DAG). DAG allows for a fully redundant configuration with onsite or offsite replication. Microsoft has changed the architecture of Exchange so that the mailbox database is no longer tied to a specific server. DAG permits a mailbox database to be replicated to up 16 different servers. What’s more the configuration has been highly simplified and can be fully managed from the Exchange Management Console. You can even configure a single server for DAG and then add a second server at a later date without reconfiguring.
In addition to DAG Microsoft has improved the consistency of mail delivery with the concept of Shadow Redundancy. Where DAG applies to the availability of mailbox database, Shadow Redundancy handles providing redundancy for messages during the transportation process. Basically each server in the transportation process holds onto a copy of a message until it receives confirmation that the message was received by the next “hop” in the process. If confirmation isn’t received the message can be resubmitted to the next server or an alternate server if one is available. Unfortunately, Shadow Redundancy can only be used up to the point the mail is forwarded to a server that doesn’t support this functionality. But, it is a big step forward in ensuring consistent mail delivery within the Exchange routing environment.
Aside from high availability, there are numerous other improvements built into Exchange 2010. Some highlights include optimization for handling large individual mailboxes (10GB and larger), further improvements to Outlook Web Access (now known as Outlook Lite), and new message archiving and compliance functionality out of the box. These are valuable improvements that I’ll expand on at a later date. But, email has become a mission critical application in organization large and small these improvements to increase the uptime of Exchange are by far the most compelling.