In a two-node Windows Server 2008 failover cluster, is it required that the machines be identical? We're looking to utilize existing hardware to reduce downtime using one very fast server and one only moderately fast server, both Dell PowerEdges but of different generations.
I've found the following suggestions that you should use matching hardware, but will we be able to achieve our goals of increased availability using different servers? And if so, what types of issues should we look out for with this type of configuration?
From MS TechNet: Appendix A: Failover Cluster Requirements
We recommend that you use a set of matching computers that contain
the same or similar components.
From Windows Server 2008: Inside Out
You should use identical hardware in all clustered servers. Using identical
hardware components makes the configuration easier to manage and can eliminate
potential compatibility issues.
Best Answer
They are not required, but as you have quoted, they are recommended.
I have seen clusters where one half is a physical machine and the other is a VM.
edit
For support reasons in most cases you should not, but during a failover, as long as both sides of the cluster are able to handle the resource shift, you should be fine.
If all sides of the cluster have the necessary hardware, and resources, to handle a failover, it would be perfectly acceptable.
You can also run cluster validation to ensure everything will be fine.
You might want to make sure that the configuration you are running is supported though, since your server vendor and/or Microsoft might refuse support if it is not.