Time to pay the bills! Exchange 2003 and GeoCluster.

Exchange 2007 introduced the idea of Cluster Continuous Replication (CCR) to the world, allowing you to extend an Exchange Cluster between sites (especially on Server 2008) and to create more than one copy of the mailbox data. Exchange 2010 will introduce Database Availability Groups (DAG), further pushing the technology to provide up to 16 total copies of the mailbox data in any number of locations. Both of these technologies are stellar in their own right, but leave those who are still running Exchange 2003 solidly in the dust. Granted, Exchange 2003 is nearing end-of-life, but with a large portion of the market still running on it (at the very least until the upgrades are done), many folks need solutions.

As I work for Double-Take Software, of course I’m happy to advocate our cluster-extending technology to help alleviate the situation on earlier versions of Exchange Server. This is both because they pay me to vocally advocate it (the FCC may be watching) and because it works remarkably well. More so for the latter reason.

GeoCluster (which was once a stand-alone product but is now a feature set of Double-Take Availability), allows you to create a Microsoft Cluster using Microsoft Clustering Services (MSCS) on Server 2003, but to do so without creating a shared-disk configuration that could lead to a single-point-of-failure and will restrict you in terms of how far apart the nodes can physically be. The idea is simple, GeoCluster works under the hood of MSCS, replicating data on each disk resource from the owning node to all potential owning nodes in the cluster. So Exchange sees a traditional cluster, but in reality the disks are replicated, creating multiple copies of the data based on the active node for each disk.

Since GeoCluster can support any valid cluster configuration, you can freely create clusters that span more than 2 nodes, or even more than one physical site. Keep in mind, however, that you’ll still be limited by single-subnet restrictions in Server 2003’s MSCS implementation. The good news is that moving resources from node to node works exactly the same was as it would in a shared-disk cluster, and therefore automatic failover and on-command moves are all possible.

If you lose a node, GeoCluster lets the MSCS engine arbitrate who should take over, then begins replicating data from that new owner to all the other, surviving, potential owners. Once you repair or replace the original node, the system will sync up the volumes and be ready to allow you to move the resources back to the original node if you want to. This replication is all done with the Double-Take Replication Engine, which allows GeoCluster to have the same level of write-order integrity and data reliability as any other Double-Take connection.

So, until you’re ready to make the jump to Exchange 2007 and beyond, or if you cannot take advantage of CCR for whatever reason, have a look at the GeoCluster solution. It is a cost effective and reliable way to make MSCS even more flexible and reliable, and does so without making Exchange work differently than it was designed to function.

Don’t believe me?  Check out this TechNET blog post about what the MSFT Virtualization Team does with partners like DBTK.  We help them with clustering solutions for Hyper-V, and can help you with that and much more.

Tomorrow, back to my usual, non-vendor-specific stuff =)

Webinar coming up!

Please feel free to register for the Double-Take and Microsoft Exchange Ecosystem Protection Webinar.  It’s going to be on September 9th at 11am Eastern Time.

I’ll be presenting for Double-Take, and we’ll be joined by a (as yet not able to disclosed) Microsoft guest speaker as well.

You can register here to join the Webinar free of charge:

Exchange Ecosystem Protection from Double-Take and Microsoft

As for what we’re talking about, well, you can watch this video where I explain it:

Yep, that’s my ugly mug doing the teaser video =)

Hope to see you all there on September 9th!

From the field

Brace over at Double-Take Software had a great report from the field with info for those folks who are about to move their Exchange infrastructure to a new location:

"A good engineer that I worked with on a Dell project contacted me yesterday and brought up a good question. He is working with a client in New England and they are in the process of planning to move their Exchange Server to a different site subnet. Because Exchange is so tightly integrated with Active Directory there is much more to plan for with moving Exchange than there is Double-Take. However, the question is below and I have some answers from our of our own PS engineers.

"I'm working on a project where the customer needs to change the IP address of all their existing Exchange 2003 servers and move them to another subnet. I'm familiar with the process for Windows and Exchange, but how does that affect Doubletake? Are there any KB articles that might explain the process?"

If using the DTAM functionality within Double-Take it should be as easy as re-enabling protection once the server has been moved. "Just disable protection before doing the re-IP'ing, then go back through setting up the protection afterwards. Should probably not select the "use last configuration" or whatever that option is...since it might get the wrong IPs."

Pretty easy but as a best practice you should always contact our technical support department for any tpe of planning deployment just to verify potential changes being made. Double-Take Technical Support can be reached at 24/7 at 800-775-8674 or 317-598-2066.
For Technical Support in the European Union +44 (0)1905 330820 +33 (0)1 47 77 15 06 +49 69 6897776-66
Or find answers online at support.doubletake.com!"


Of course, that client would probably want to check out the latest version of the Full-server Failover Option too, as that could make life a lot easier during migrations of Exchange, or anything else running on Windows.