Requirements for witness server in a mirroring setup

[RRinTetons]

I'm checking on my understanding of the requirements for a witness server for use in the mirror set up. It sounds like the witness server can be any version of SQL Server, Enterprise, Standard, Express, Developer or anything else. It also sounds like it can be any version number, i.e.-SQL Server 2008 or SQL Server 2005. It doesn't actually handle any workloads, the server it runs on can be quite modest, even a fairly minimal virtual machine. Since the witness server is required for a quorum if one of the pieces of the mirror goes away, it shouldn't be a complete piece of junk, but it doesn't have to be a powerhouse by any means.

I've got 2 identical, very beefy, pieces of physical hardware for the principal and mirror, both 64-bit machines running SQL Server 2008 R2. I'm just trying to figure out now what do the witness.

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Richard Ray
Jackson Hole Mountain Resort