Exchange 2007 and Standby Continuous Replication (SCR)
Posted September 29th, 2008 by Matt ShadboltI thought I would just quickly give you my take on the main benifit of moving your Exchange 2003 servers to Exchange 2007.
There are a bunch of new features within Exchange 2007 – Microsoft have really been pushing the new OWA interface – however in my opinion the greatest new feature for administrators with a simple Exchange organization design is Standby Continuous Replication (SCR).
SCR provides High Availability (HA) Exchange services by providing a redundant Exchange database that is used in a disaster scenario. In case of a minor or major disaster – you can easily cut over your users onto the remote Exchange database with very little interruption.
Although SCR seems like a HA clustering technology – it technically is not. There are no passive/active clusters, and there is no automated roll over. The live Exchange information store needs to be manually un-mounted and the SCR server needs to be “started” for the clients to regain connection. Further to that, all the log files that had been streamed to the SCR server need to be “replayed” before the mailboxes are up-to-date.
Although this may seem like an unnecessary manual process – there are good reasons why this is good design. Firstly, as this is not a clustering technology – there is no quorum disk – so your SCR server will not know if the main exchange host is not responding. This means you don’t need advanced clustering design experience – nor the skills to troubleshoot any issues you may have. Also, there is a significant saving on hardware. Secondly, in the case of a soft-failure on your exchange database (ie, a log file commit has caused the DB to become corrupt) – you can specifically choose not to replay those log files on your SCR site – thus eliminating bad data being replicated.
By using SCR in your Exchange organization we can have the benefits of semi-automatic Exchange roll over – without the over complication of having an active/passive cluster to administer.
I will be deploying an Exchange 2007 SCR solution within the coming months and will post my results.
Tags: Exchange 2007, SCR, Standby Continuous Replication
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