Even more fun with the IBM 3690, Hemisphere Mode

So, have you heard of hemisphere mode?

Hemisphere Mode is an important performance optimization of the Xeon 6500 and 7500

processors. Hemisphere Mode is automatically enabled by the system if the memory

configuration allows it. This mode interleaves memory requests between the two memory

controllers within each processor, enabling reduced latency and increased throughput. It also

allows the processor to optimize its internal buffers to maximize memory throughput.


Hemisphere Mode is enabled only when the memory configuration behind each memory

controller on a processor is identical. Because the Xeon 7500 memory population rules

dictate that a minimum of two DIMMs are installed on each memory controller at a time (one on each of the attached memory buffers), DIMMs must be installed in quantities of four per

processor to enable Hemisphere Mode.

 Our consultant didn’t follow the four per processor rule….

But then it gets even more interesting.

So I have two quad port Ethernet adapters (Intel Ethernet Server Adapter I340-T4) of course I’m not lucky enough to have them install automagically with ESX so I need drivers.

After much, much googling I hit on this post with a comment that they got it to work on their 3690 X5’s so at least I knew it was possible.

I was pretty sure that I wanted the version as verified by

I burned it, and then loaded it as an additional driver during the ESX install and that’s when it hung at “Status: 32% complete – Loading”

Gah! So I tried all sorts of iterations, flipping ports, but luckily someone else had the answer on the forum.

Even though it installed ESX just fine without the network drivers, once I included the network drivers the RAID drivers stopped working

Apparently this is a known issue with the new version of the firmware for the M1015 (which I of course flashed it to)…

So, download the updated megaraid driver, burn it to disk,

And now I can install ESX…. That was easy