ESX 3i Processor Performance: More slow cores, or less fast cores?

[cforger]

Hi,

I'm trying to decide between deploying ESX 3i on;

a) Two Quad-Core low-speed Xeons (say 1.6- 2 Ghz)

-or- b) One Quad-core High Speed Xeon (say 3.33 Ghz)

The money is about the same between the two of them.

I'll be using 15k SAS drives in a RAID10 arrangement, running 64 Bit Windows 2008 as a Terminal Server, with 1-2 other Windows servers running in the VM Space. I will had a seperate virtual striped array off the PERC 6i to run swap files. The main RAID10 array will share disk space with the other VM's.

I'll have plenty of RAM: 16-30 gig, so it won't be starved.

In the end, what will make the largest difference to the perceived user environment? I was a server that seems to run their Word/Excel/Outlook centered day as snappily as possible.

I know there is some overhead in any SMP, and I believe a quad-core is superior to two-dual cores, as there is less ovehead when the cores are on the same die (correct?).

Does the way VMWare virtualized the CPU's and threads make it less necessary to have lots of cores available to keep response time high?

Any comments will be appreciated here.

Thanks.

[williambishop]

You'll get better density on the dual socket, because you're not waiting as long to cycle....If the vm's don't need the speed difference of the higher speed one, my recommendation is always to go for more units, vs. faster units. Of course that is preference, but I've been adminning vmware from some of the first dual cores to the newest quad cores, and I've always found the sweet spot to be a dual proc, quad core setup.

W

[mcowger]

If thats your tradeoff, for most workloads, go with more cores.

--Matt

[Anders_Gregerse]

It's like choosing between a few big drives or more but smaller drives. It depends on your needs. Do you need the performance of the fast cpu or be able to run more vm's in parallel with a greater number of cores. If you got few but heavy loaded vm's using only 1 vcpu I would choose the fast cpu, but if you have more light loaded vm's I would go for more cores.

I'm planning to run a terminal server on each of our vm's and then loadbalance them with 2X. It should give the users a better experience and greater availability.

[christianZ]

Well you will have 3 vms and e.g. 4 cores - i.e. one core - console, and for each vm one core. Thast would be ok. But when one of your vm needs more vcpu or you even get more vms than the option with dual quad core should be better. And I remember a VMware session saying larger cpu cache is even more important than cpu speed.

OK. The 3i hasn't any console yet.

Message was edited by: christianZ

[VkernelRB]

Anders,

For your clustered (2x) Terminal Services - what did you go with for CPU/Cores?

And how many users are you supported and how many Terminval Server VM's are you going to Run? Also interested in how much RAM you gave each VM and had in each ESX host.

Thanks,

Rob

Rob Bergin

Systems Engineer

www.vkernel.com

Managing Virtualization with Virtual Appliances

To download a free trial of our products, click here:

[cforger]

Thanks all. Yes, more cache and faster FSB's are always a consideration for me, but I will go for more cores first, and then find the sweet spot in price for clock rate.

[Anders_Gregerse]

Well, I have been running vmware for about 4-5 years so I have a mix of hosts, all of the 2 socket servers, but the old ones (3 of them) are dual-core with 16GB and the new ones (3 of them) are quad-core with 32GB all of the AMD. Currently we have two virtual terminal servers and that is going to be increased to 4 (distributed on 6 hosts) where they have 1 vcpu and 2Gb memory. I'm supporting from 50-150 users. Small setup.