On 09/15/10 2:19 AM, Rudi Ahlers wrote:
Hi all,
I'm just curios and would like some input from the community on this one. We're busy budgeting for a couple of new servers and I thought it would be good to try out the Core i7 CPU's, but see the majority of them don't offer VT-d, but just VT-x. Looking at the LGA1366 range, only the "Intel lga1366 i7 980XE" (from the list of what our suppliers stock) have VT-d, and it costs 4x more than "Intel lga1366 i7 930" or 2x more than "Intel lga1366 i7 960". From a budget perspecitve I could purchase 4 more CPU's, which could translate to 40x - 80x more VM's being hosted for the same capital outlay. Experience has shown that we under-utilize CPU's by a great margin and memory / HDD IO is our biggest bottleneck on any server.
So, if VT-d really necessary? We mainly host XEN virtual machine for the hosting industry, i.e. we don't need / use graphics rendering inside VM's, or need DAS on the VM's, etc.
Core I7 is the branding for the desktop CPU family. The Server processors are branded Xeon 5500 and 5600 (for dual socket servers) and Xeon 7000 for 4+ socket servers. Typically, desktop processors go with desktop motherboards which don't support ECC memory, probably don't have remote management features, likely don't readily support redundant power, and often have only a single NIC onboard. A server board will likely have significantly more IO bandwidth, oriented towards network and disk IO rather than graphics.
IMHO, the dual socket 5600 family is the sweet spot of price/performance for a VM host, with 2 x 6 cores, and typically 12 memory slots (2x3 per CPU). populate the memory with 6 matching DIMMs for best performance.