Over the last two weeks I’ve had a number of confrence calls with my Dell sales rep and some engineers about the new Xeon 5500 / “Nehalem” based blade servers, and specifically over the memory configurations thereof. I have learned one thing for certain, this shit is impossible to explain without pictures.
The good news is, eventually I stumbeled across this great writeup with pictures on the Dell TechCenter Wiki: Nehalem and Memory Configurations
However its still a lot of words, and requires some intepretation to adapt to the M610, so with that in mind here is my explanation in ms-paint form:
Channels, Banks, and Slots
The Good Configs
Read the linked article for why, but the short of it is:
- you want all your sticks of ram to be the same size
- you want to use either 6, 8, or 12 slots at a time
- you want to use 4GB or 8GB sticks. Smaller would add up to less than 3GB-per-core, and given how much ass these kick at vmware that’d be a weird config.
Wait, what? Show me
6 slots
- 6 x 4GB = 24GB
- 6 x 8GB = 48GB
- can run at 1333MHz or 1066MHz, uses all 3 channels per socket (best memory bandwidth option)
Eight slots
- 8 x 4GB = 32GB
- 8 x 8GB = 64GB
- because two slots per channel are populated can only run up to 1066MHz
Twelve slots
- 12 x 4GB = 48GB
- 12 x 8GB = 96GB
The Neckbeard Take? (sorry storagemojo)
6×8GB for 48GB is probably the sweet spot. It gives the best memory bandwidth performance and a 6GB-per-core ratio thats a good midrange for virtualization.
NOTE: HUGE CAVEAT! – 8GB sticks aren’t available for purchase yet. So if you plan on running vmware on these, you have a two month wait ahead of you.
Links
ran into some other good posts while I was at this, here’s the links