My organization is in the process of rolling out SharePoint 2010 - thus far the WFE, App, and SQL servers are all going to be deployed in the virtual environment but our consultant is holding out on the FAST Search Server module due to I/O performance concerns. They are referencing a Microsoft study that benchmarked the FAST component on Hyper-V in late 2010 and compared physical and virtual installs (see link). They found that performance was anywhere between 30-70% poorer running virtual due to I/O - I obviously have a hard believing these same numbers can be applied to a properly configured vSphere/ESXi 4.1 implementation. I'm sure it will be resource intensive, but that's fine I have plenty of resources in my cluster and will be upgrading to v5.0 in the next 6 months or so, further removing any scaling limitations. Our storage backend performance (FAS3240) is no concern whatsoever for at least our initial implementation, physical or virtual.
So, does anyone have any experience virtualizing the FAST search component? What kind of SharePoint environment are you running it on (userbase / object count)? I've found little information on the interwebs in regards to this other than the Microsoft capacity white paper:
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=5120
Thanks.
-Adam