AMD hexa-core or Intel Sandy Bridge quad-core for OpenVZ?

[gkovacs]

I am looking to build a couple of new servers that will host OpenVZ and KVM virtual machines. As our experience shows, usually disk IO wins over processor performance in the long run, so there is no point in buying Xeon or Opteron grade hardware for us at 3-4x the price per server, we are better off by assembling more cheap nodes.

Currently there are two contenders for these new nodes:

AMD version
880G+SB850 motherboard, 16GB DDR3 RAM, PCIe RAID
Phenom II X6 hexa-core processor @ 3-3.2 GHz (1075T or 1090T)

Intel version
H67 motherboard, 16GB DDR3 RAM, PCIe RAID
Core i5 2x00 quad core processor @ 3.1-3.3 GHz (i5 2400 or 2500)

Since I was unable to find any meaningful comparison benchmarks between the two, I'm asking for advice: given the typical VPS workload (mainly OpenVZ LAMP servers and some KVM machines), which one would be the better choice?

I'm also interested in any comparison benchmarks showcasing CPU or IO performance regarding these two architectures that others have seen.

[curaga]

Will you run more than four VMs at once? There's the question

[Kano]

The speed should not be much different until you get an i7-2600 instead of i5-2500. i7-2600 would be even faster than a 1100T on many workloads . Most likely Intel will need less energy when not idle. There are of course apps which really like amd cpus, so maybe get one of each system and benchmark with your apps.

[chithanh]

You could get one of the new AM3+ mobos, then you can upgrade to 8-core Bulldozer CPUs if at some point the X6 turns out to be insufficient.

Another thing to consider is that 16 GB RAM is not much if you are heavily into virtualization. In many socket 1366 mobos you can install 24 GB (6x4GB) without breaking the bank.

[Kano]

I would not buy LGA 1366 boards now. LGA 2011 will replace it (chipset X79). But those boards will not be cheap anymore...

[gkovacs]

These are all interesting points, however I'm still interested in seeing any benchmarks comparing Intel Sandy Bridge and AMD Thuban.

curaga: Of course I will be running more than 4 VM's at once on a given node, but I don't see how that's relevant. Any server running even a low number of virtual machines has hundreds of processes, so single core performance, inter-core communication and cache/memory access are probably much more important than the sheer number of cores.

Kano: Yes, we are thinking about the i7-2600 as well, HyperThreading looks promising but I would die to see some benchmarks that justify the cost increase.

chithanh: Since we are mainly running OpenVZ, maximum memory size is not a big consideration since it doesn't reserve private memory for each VM, rather it shares very efficiently. A single socket node with locally attached storage will usually reach it's IO or CPU limits well before running out of memory.

[chithanh]

You can buy 8 GB DDR3 UDIMMs today, eg. the Axiom AX31333E9Z/8G. But they are what I was referring to as "breaking the bank".

[Kano]

Maybe you should consider ecc ram, but then you can not use the cheaper intel chipsets + you need a Xeon branded cpu.

http://www.intel.com/support/motherboards/desktop/sb/cs-009023.htm

[gkovacs]

Wow thanks everyone for hijacking my first thread while not giving any meaningful input to the originally posted questions.
I wish you all great success buying 8GB memory modules...

[Kano]

It is simple choice now: if money is most important and you want to use ecc ram you can only get an amd system. intel + ecc ram is much more expensive...