Let’s face it. Virtualization is everywhere.

Odds are there is something virtualized in your data center. If not, it soon will be. As more workloads become virtualized, chances are you are going to run out of “capacity” on your virtualization host. When a host’s capacity is exhausted, 99% of the time it is because the host ran out of memory, not CPU. Typically you would have to add another ESX host server when you run out of capacity. When you do this, you are adding more hardware cost AND more virtualization licensing costs. But what if you could simply add memory when you need it instead of buying more hardware. Now you can with Dell’s FlexMem Bridge.

You may recall that I mentioned the FlexMem Bridge technology in a previous post, but I don’t think I did it justice. Before I describe what the FlexMem Bridge technology, let me provide some background. With the Intel Xeon 7500 CPU (and in fact with all Intel Nehalem architectures), the memory is controlled by a memory controller located on the CPU. Therefore you have to have a CPU in place to access the associated memory DIMMs…up until now. Dell’s innovative approach removed the necessity to have a CPU in order to access the memory.

Introducing Dell FlexMem Bridge
Dell’s FlexMem Bridge sits in CPU sockets #3 and #4 and connects a memory controller from CPU 1 to the memory DIMMs associated to CPU socket #3 and CPU 2 to the memory associated to CPU Socket #4.

The FlexMem Bridge does two things:

  1. It extends the Scalable Memory Interconnects (SMI) from CPU 1 and CPU 2 to the memory subsystem of CPU 3 and CPU 4.
  2. It reroutes and terminates the 2nd Quick Path Interconnect (QPI) inter-processor communications links to provide optimal performance which would otherwise be disconnected in a 2 CPU configuration.

Sometimes it’s easier to view pictures than read descriptions, so take a look at the picture below for a diagram on how this works.

(A special thanks to Mike Roberts from Dell for assistance with the above info.)

Saving 50% on Virtualization Licensing
So how does this technology from Dell help you save money on virtualization licenses? Simple – with Dell’s FlexMem Bridge technology, you only have to add memory, not more servers, when you need more capacity for VMs. When you add only memory, you’re not increasing your CPU count, therefore your virtualization licensing stays the same. No more buying extra servers just for the memory and no more buying more virtualization licenses. In the future, if you find you have run out of CPU resources for your VM’s, you can remove the FlexMem bridges and replace with CPUs (for models with the Intel Xeon 7500 CPU only.)

Dell FlexMem Bridge is available in the Dell PowerEdge 11G R810, R910 and M910 servers running the Intel Xeon 7500 and 6500 CPUs.