Evan Dodds - Microsoft Exchange Server Blog

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Paul Robichaux on Geoclustering

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Paul Robichaux commented on Geoclustering in last week's edition of the Exchange and Outlook Update. He points out that it can be quite expensive, but that it can also be a very good (and this is key: Supported/Tested) way to span your Exchange servers across multiple sites to prepare for disaster avoidance.

There was some discussion in the comments area of a previous message on this blog about some alternate ways to do “hotspare”-type disaster recovery environments as a method of avoiding the costs and limitations of geospan clustering. There's still some internal investigations going on about just what non-standard sorts of recovery environments can be supported by Microsoft PSS, so that comment thread isn't really totally dead yet, I suppose.

That said, I'm curious to hear from you in the comments: What sort of geo-clustering or clustered-Exchange disaster-recovery concerns do you have that affect your planning of these scenarios?

Comments
  • About a month ago I implemented an NSI GeoCluster solution for the company i work for. Its basically an Exchange 2003 cluster of 3 nodes spread out through a 30 mile radius. They are all interconnected via a 100GIG fiber backbone, with an OC3 BGP as a backup, along with 3 other failover methods behind that. Needless to say this is a very expensive and elaborate solution. The Exchange Database in itself is a small 10GIGs but the amount of traffic that goes through the servers is quite high on a daily basis. The geocluster solutions has proven to be quite effective in that if an active node becomes unavailable, the failover is a mere 5 seconds. Because the NSI geocluster does not use a single physically shared Database, mantainance ican be done without users experiencing any downtime, well maybe a hickup for a few seconds on outlook.

    I've also looked at Evergreen's clustering solution, but my company is totally against having outsourcing our exchange backup services.

  • We are looking into this as we speak. We need to provide site redundancy for 50,000 mailboxes. We're an EMC customer with SRDF already in place for a database application so this is technology we know. Our concern is the additional I/O latency imposed by a synchronous replication mechanism. We will be testing this in the coming months to see how viable this solution can be.

    Mike