DR For Cluster Nodes

[touchstone_81]

Hi all,

As you know in most environments, clusters operate in an active/passive mode – the passive server providing hardware redundancy. In a DR situation, generally only one of the two servers are restored. However, since we operate in active/active mode, required to support the work load, both servers must be recovered. Restoring to unlike hardware (Dell to HP) presents some additional challenges. The recommended approach is to build the systems from scratch. However, based on comments during our weekly meeting that installing the application from scratch would take days, and so is not feasible.

Currently we are looking at a software known as Double-Take which is mighty expensive and not sure if this would overcome the disk signature problem.

If anybody has any ideas or has been in a similar situation please share your ideas.

Thanks in advance.

[cluberti]

Double-take basically copies the data from one machine to another (it's not a cluster, it's replication of data). I've used it in the past, and while it's good for web farms or static data applications, it's not as useful when the data is disparate on multiple cluster nodes. Also, restore with double-take can take quite awhile as well depending on the size of the data store, but it does work.

For a Windows cluster DR situation, it matters more what application you'd be recovering rather than Windows clustering. Building a Windows cluster from scratch takes only a few hours - restoring your app and data is where the problem of time comes in. What exactly are you running in cluster, and why is there not at least one passive node (3 node cluster) to handle a failure of at least one of the nodes?

[touchstone_81]

Hi Cluberti thanks for the reply.

There are 2 clusters each with 2 nodes and it is in active/active mode because thats a client requirement.The applications are SAP management apps supported on an Oracle database which are administered by the client.

[touchstone_81]

Due to shortage of time we have decided not to use any 3rd party software in our DR test.But now the problem is that we are using 64bit win2003 R2 and this is not supported by the dumpcfg.exe (used to change the disk signatures) tool.

Read somewhere that the registry can be modified to point to new disk signature .If Cluberti or someone knows which keys to change i would be grateful.

Edited October 7, 2008 by touchstone_81