Yellow Bricks

by Duncan Epping

site recovery manager

Stretched Clusters and Site Recovery Manager

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My colleague Ken Werneburg, also known as “@vmKen“, just published a new white paper. (Follow him if you aren’t yet!) This white paper talks about both SRM and Stretched Cluster solutions and explains the advantages and disadvantages of either. It provides a great overview in my opinion on when a stretched cluster should be implemented or when SRM makes more sense. Various goals and concepts are discussed and I think this is a must read for everyone exploring implementing a Stretched Clusters or SRM.

http://www.vmware.com/resources/techresources/10262

This paper is intended to clarify concepts involved with choosing solutions for vSphere site availability, and to help understand the use cases for availability solutions for the virtualized infrastructure. Specific guidance is given around the intended use of DR solutions like VMware vCenter Site Recovery Manager and contrasted with the intended use of geographically stretched clusters spanning multiple datacenters. While both solutions excel at their primary use case, their strengths lie in different areas which are explored within.

Avoid changing your VMs IP in a DR procedure…

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I was thinking about one of the most challenging aspects with DR procedures, IP changes. This is a very common problem. Although changing the IP address of a VM is usually straight forward it doesn’t mean that this is propagated to the application layer. Many applications use hardcoded IP addresses and changing these is usually a huge challenge.

But what about using vShield Edge? If you look at how vShield Edge is used in a vCloud Director environment, mainly NAT’ing and Firewall functionality, you could use it in exactly the same way for your VMs in a DR enabled environment. I know there are many Apps out there which don’t use hardcoded IP adresses and which are simple to re-IP. But for those who are not, why not just leverage vShield Edge… NAT the VMs and when there is a DR event just swap out the NAT pool and update DNS. On the “inside” nothing will change… and the application will continue to work fine. On the outside things will change, but this is an “easy” fix with a lot less risk than re-IP’ing that whole multi-tier application.

I wonder how some of you out in the field do this today.