[rhythm]

Hi folks,

So I have been tasked to do an upgrade of a cluster in the company that is coming to an end of its life.
To give a bit of a background on what the setup is currently - the cluster is based on beowulf structure with 14 compute workstations and 1 head node workstation in place and primarily these are used to run OpenFOAM simulations (pre-processing and computing, but not post-processing). Because the current system configuration is rather cumbersome to manage, the idea is to upgrade everything using OpenHPC package with stateless compute nodes, which hopefully will make it easier to manage the system.

There has been a budget of £10k assigned for this, which is obviously not enough to do a full replacement upgrade, therefore we have decided to do it incrementally over the next couple of years, whereby this year a head node will be replaced and a new compute node will be added (with possibly a few older ones being retired).

Based on the info on the benchmark sticky post I think that we will be going with the following compute node:

• Tower Chassis, 8x 3.5" Hotswap Drive Bays 1280Watt Platinum Redundant Power Supplies;
• X11DSI-NT, Dual 10GbE LAN, Decicated IPMI & Remote KVM, 16 Dimm, On Board Graphics;
• 2 AMD EPYC ROME 7452, 32 Core 64 Threads, 2.35GHz, 128MB Cache, 155Watts;
• 2 Supermicro 4U Active CPU Heat Sink for AMD EPYC CPU;
• 16*16GB DDR4 2933MHz ECC Registered DIMM Module;
• Onboard graphics;
• 1280Watt Platinum Redundant Power Supplies.

Two questions that I have about this configuration:
- Would going with 155Watt CPUs rather than 180W or 225W impact the performance significantly? Most often the machine will be used to run 10-20million cell cases.
- Is 256GB too much or too little of memory? (I know that there's never too much memory, but DDR4 registered ECC is damn pricey :/ )


In regards to the head-node I wasn't able to find any conclusive advice. Here are some questions that I currently have:
- What recommendations would anyone have for the head node configuration?
- How much RAM one would need to have on it so that there was no bottleneck?
- Any other important things to consider so that the system worked with as little of bottlenecks as possible?

Thanks,
Ben