Ah, I see. I thought maybe the SBS stuff was the primary use.
So you have 2 virtual machines running on there. Are both of the VHD files on that same G: drive? And to confirm, "G:" is a RAID 1 with a pair of 2TB SATA drives?
I'm assuming you're using Hyper-V as the host. I guess it depends on what kind of workload is running on those virtual machines. How many CPU's and memory are assigned to each of the virtual systems? You could assign 8 CPU's to each machine... if they both (and the host OS) are all super busy, then yeah, they'll have to schedule their slices, but odds are they're not ALL going to be super busy at the same time too often. And if one virtual is more important than the other, just set the priorities accordingly.
You had mentioned you saw 1 core running at 100% use. Is that one of the 8 cores total then? Is whatever app that's using all that CPU doing something to set the affinity to a single core, or was it spreading it out, just using 12.5% of the total system CPU?
You can probably just look in task manager either on the host system or in the virtual machines to see what's using so much CPU and why it doesn't seem to be a multi-threaded app.
And again, just like with my answer above regarding Exchange, if you have a couple of virtual machines sharing a disk, if they're doing some I/O intensive things, you could be running into some contention. The disk queue length and read/write per second stats in performance monitor can help you get a better idea.
Getting to the right answer depends on being able to figure out where exactly the bottleneck is. My gut instinct tells me it's the disk subsystem, but when you say there's something using 100% of a CPU that means it's either not multi-threaded, or it's affinity was set to a single CPU.
If that were the case, some single-core app is your main thing, then going to a lower speed CPU could very well cause problems. I've seen my fair share of "dumb" non-threaded apps, some of them by HP themselves (I'm looking at you, VCRM). In those cases, you want the fastest speed possible for a single core, irregardless of how many total cores, hyper-threading, etc. the system has.
For a well-behaved multi-threaded app, it's possible to go from a higher speed system to a slightly slower one but with more total cores and still see an overall improvement. You also benefit from the improvements from one generation of Xeon to the next, even at the same clock speeds.
You could check some of the benchmarks on CPU to see how the E5-2403 compares to the E5345. The good folks over at Passmark are a good resource:
E5-2403: 3489 (avg CPU mark)
E5345: 2973 (avg CPU mark)
So in theory, the E5-2403 is a bit faster even though it runs at a slower clock rate. I'm still thinking disk is your slow point.
So you have 2 virtual machines running on there. Are both of the VHD files on that same G: drive? And to confirm, "G:" is a RAID 1 with a pair of 2TB SATA drives?
I'm assuming you're using Hyper-V as the host. I guess it depends on what kind of workload is running on those virtual machines. How many CPU's and memory are assigned to each of the virtual systems? You could assign 8 CPU's to each machine... if they both (and the host OS) are all super busy, then yeah, they'll have to schedule their slices, but odds are they're not ALL going to be super busy at the same time too often. And if one virtual is more important than the other, just set the priorities accordingly.
You had mentioned you saw 1 core running at 100% use. Is that one of the 8 cores total then? Is whatever app that's using all that CPU doing something to set the affinity to a single core, or was it spreading it out, just using 12.5% of the total system CPU?
You can probably just look in task manager either on the host system or in the virtual machines to see what's using so much CPU and why it doesn't seem to be a multi-threaded app.
And again, just like with my answer above regarding Exchange, if you have a couple of virtual machines sharing a disk, if they're doing some I/O intensive things, you could be running into some contention. The disk queue length and read/write per second stats in performance monitor can help you get a better idea.
Getting to the right answer depends on being able to figure out where exactly the bottleneck is. My gut instinct tells me it's the disk subsystem, but when you say there's something using 100% of a CPU that means it's either not multi-threaded, or it's affinity was set to a single CPU.
If that were the case, some single-core app is your main thing, then going to a lower speed CPU could very well cause problems. I've seen my fair share of "dumb" non-threaded apps, some of them by HP themselves (I'm looking at you, VCRM). In those cases, you want the fastest speed possible for a single core, irregardless of how many total cores, hyper-threading, etc. the system has.
For a well-behaved multi-threaded app, it's possible to go from a higher speed system to a slightly slower one but with more total cores and still see an overall improvement. You also benefit from the improvements from one generation of Xeon to the next, even at the same clock speeds.
You could check some of the benchmarks on CPU to see how the E5-2403 compares to the E5345. The good folks over at Passmark are a good resource:
E5-2403: 3489 (avg CPU mark)
E5345: 2973 (avg CPU mark)
So in theory, the E5-2403 is a bit faster even though it runs at a slower clock rate. I'm still thinking disk is your slow point.