In Exchange 2007, Microsoft created several new features in the high availability/reliability and data storage redundancy spaces. With these new names floating around, there is some confusion as to the differences and similarities between Single Copy Clusters, Local Continuous Replication, Cluster Continuous Replication, and now with Exchange 2007 Service Pack 1, Standby Continuous Replication. This installment attempts to clarify some of these technologies.

Single Copy Clusters (SCC) uses at least two servers and a shared disk storage to house the database, logfiles, and quorum. This provides redundancy with the Exchange server utilizing Microsoft’s clustering solution to provide a “floating network identity” as Microsoft so eloquently puts it, while still retaining a single point of failure at the storage (usually a SAN) level. Typically, customers deploying SCC have policies in place to provide some form of redundancy and spare disks to the SAN, or at least some type off-site disaster recovery. Failure of the storage device hosting the data does not result in automatic recovery. This can result in outages, or even data loss and corruption. There is also an inherent potential vulnerability in having a single quorum disk. This method does, however, provide redundancy in the Exchange service.

In 2004 Google announced that it was building a messaging service called “gmail” that would allow users to have 2+ GB of online storage available for each user, as part of their “Infinity+1”
storage plan storage plan. Shortly after Google announced their gmail service, Microsoft and Yahoo matched the 2+ GB offer on their hosted service platform.

The result? Today almost all free web based email services offer 2+ GB of online storage for their email users. This then started discussions in the corporate world mainly at the C-level, as many CEO’s and CIO’s thought that “If Google can do it for free then why am I fighting my IT department for another 50MB?” This in turn made for a lot of anguish throughout IT departments around the world.

Thanks for the introduction Keith, I remember the polar bear kidnapping incident well and it still makes me laugh to this day when I hear that story.

I wanted to post my first blog this week to introduce myself and talk about some of the exciting challenges ahead. First of all I have to say that I am delighted to be part of the Azaleos team, Azaleos has gathered a group of very talented and motivated engineers to deliver world class solutions that can be delivered in a unique way to our customers. I look forward to the challenges ahead and especially look forward to working with our customers to improve our solutions to meet your needs.