perhaps you should start with the SAN design guide: http://www.vmware.com/pdf/vi3_san_design_deploy.pdf - e.g. page 73 where there is something about whether it's better to make one big vmfs or smaller ones. E.g. normal values are around 15 to 25 virtual machines per VMFS. The right design can be a bigger advantage than the Linux IO scheduler.
The problem is that it also depends on the IO load of your VMs... So perhaps the best way is trial and error...
In my case, I won't be running many VMs. A few mission-critical VMs from our main site will be replicated to this location for DR purposes but we won't actually run them unless we're in DR mode. There will still be a few VMs running in production at this site, but by a few I mean a half dozen at most. It's really a small location that doesn't need much storage but we have this existing box that I can redeploy. Just trying to get an idea of how to optimize it.
So, worst case, if we were in DR mode we might have to run as many as 10-15 VMs, but in that case we're looking more towards accessibility of data rather than performance. So for performance I'm just looking at optimizing for around 5-6 production VMs running at any one time. The VMs will be a combination of Linux and Windows, mostly Linux.
Joe
