Sql-server – Active/Passive to Active/Active

clusteringsql serversql-server-2008

In layman terms, what does it mean to have "Active/Active"? What are the steps to achieve this configuration?

Edit:
We currently have an "Active/Passive" setup which isn't efficiently making use of the hardware so we need a "Active/Active" configuration.

Best Answer

Active/Active could mean two things (or maybe others depending on the project manager's imagination).

  1. At least two clustered instances of SQL Server on two nodes of a Windows cluster. This allows both pieces of hardware to be used simultaneously and not wasted, one server for each instance, with the worst case scenario being one server fails and the other takes all of the load for both instances in that case.

  2. More likely, a manager thinks that both nodes of a cluster could be actively running the same instance of SQL Server, with reads and writes going to both. This is not how clustering works; it is not for scale out but for high availability / disaster recovery. But it is a common misconception, especially for managers. :-)

Most people that work with clustering regularly cringe when they hear active / active. It's inaccurate, ambiguous, and to them it's like nails on a chalkboard.