Workstation for post-processing of large cases

RedoFromStart · August 29, 2018, 12:11

Hello!
I am in need of a workstation capable of post-processing large cases - usually between 70 and 100 million hexahedral cells.
The software I am going to use is Fluent and CFD-Post.
My budget is about 8000 Euro.
Please ask if any further information is needed.

flotus1 · August 30, 2018, 04:40

You are probably looking for these specs:

A single CPU with only one NUMA node, decent clock speeds and around 8-12 cores. E.g. Xeon W-2145.
At least 128GB of ECC memory. 4x32GB and a motherboard with 8 DIMM slots if you stick with a Xeon W.
2TB or more of NVMe-based storage
A good Nvidia graphics card with plenty of VRAM, e.g. Quadro P4000 or P5000.
Depending on how you get the data to this workstation: 10GBit Ethernet or more.

RedoFromStart · August 31, 2018, 14:27

Can you suggest any other CPU?
The one you specified is hard to get in my country.

flotus1 · September 3, 2018, 06:25

Hmm...you could drop down to consumer CPUs like the I7-7820x or I9-7900x.
But these do not support more than 128GB of RAM (8*16GB) and also lack ECC support.

I don't feel qualified to judge whether one of those might be a deal-breaker for you. I honestly don't know how much RAM CFD Post will use for your applications.

Reading the initial post again got me thinking: Is this thread for a "general purpose" workstation that will also run simulations or is it specifically for post-processing? My initial recommendation was for a dedicated post-processing workstation. It severely lacks performance for CFD simulations and does not have enough RAM to run most simulations with this cell count. E.g. Fluent coupled solver in double precision uses 3-4GB of RAM per million cells.

RedoFromStart · September 3, 2018, 17:42

The workstation is specifically for post-processing.
Simulations are performed on a cluster.

I think that CFD-Post has similar requirements for hardware as Paraview if it helps you with judgement.

Is ECC crucial for such task? From what I've read its usually slower than normal RAM.

flotus1 · September 3, 2018, 18:11

The performance difference for ECC vs. non-ECC is in the low single-digit percentages for the same rated speed.
What is different is that with an I7 or I9 CPU you could use faster memory. Xeons these days are completely locked, so DDR4-2666 is the highest possible memory speed. Other current-gen CPUs can go way beyond that.

Do you need ECC or not... controversial question. Some folks would burn you at the stake for even mentioning non-ECC memory. Others are running entire clusters with non-ECC memory without any issues.
In my opinion it depends on the scope of application. If you are in a larger company, consult your IT department. They might have a policy concerning this topic. Otherwise ask yourself the worst-case question: how bad would it be if this workstation did an unintentional crash, losing a few hours of work. Or if it produced a bogus result due to a flipped bit. How much money is involved in the results you produce? Are the results relevant for safety of people or machinery?
If you can take those risks in exchange for a cheaper and/or faster machine, non-ECC might be for you.

JBeilke · September 4, 2018, 08:08

It very much depends on what type of data you have (steady or transient) and what type of postprocessing you want to do:

- calculating numbers
- section and vector plots
- volume rendering
- Virtual Reality

512 GB of main memory is probably not too much :-)

August 29, 2018, 12:11	Workstation for post-processing of large cases	#1
RedoFromStart New Member Join Date: Dec 2017 Posts: 10 Rep Power: 8	Hello! I am in need of a workstation capable of post-processing large cases - usually between 70 and 100 million hexahedral cells. The software I am going to use is Fluent and CFD-Post. My budget is about 8000 Euro. Please ask if any further information is needed. Last edited by RedoFromStart; August 29, 2018 at 16:37.

August 30, 2018, 04:40		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	You are probably looking for these specs: A single CPU with only one NUMA node, decent clock speeds and around 8-12 cores. E.g. Xeon W-2145. At least 128GB of ECC memory. 4x32GB and a motherboard with 8 DIMM slots if you stick with a Xeon W. 2TB or more of NVMe-based storage A good Nvidia graphics card with plenty of VRAM, e.g. Quadro P4000 or P5000. Depending on how you get the data to this workstation: 10GBit Ethernet or more. Gerhard likes this.

September 3, 2018, 18:11		#6
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	The performance difference for ECC vs. non-ECC is in the low single-digit percentages for the same rated speed. What is different is that with an I7 or I9 CPU you could use faster memory. Xeons these days are completely locked, so DDR4-2666 is the highest possible memory speed. Other current-gen CPUs can go way beyond that. Do you need ECC or not... controversial question. Some folks would burn you at the stake for even mentioning non-ECC memory. Others are running entire clusters with non-ECC memory without any issues. In my opinion it depends on the scope of application. If you are in a larger company, consult your IT department. They might have a policy concerning this topic. Otherwise ask yourself the worst-case question: how bad would it be if this workstation did an unintentional crash, losing a few hours of work. Or if it produced a bogus result due to a flipped bit. How much money is involved in the results you produce? Are the results relevant for safety of people or machinery? If you can take those risks in exchange for a cheaper and/or faster machine, non-ECC might be for you. Gerhard likes this. Last edited by flotus1; September 4, 2018 at 06:14.

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August 31, 2018, 14:27		#3
RedoFromStart New Member Join Date: Dec 2017 Posts: 10 Rep Power: 8	Can you suggest any other CPU? The one you specified is hard to get in my country.

September 3, 2018, 06:25		#4
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	Hmm...you could drop down to consumer CPUs like the I7-7820x or I9-7900x. But these do not support more than 128GB of RAM (8*16GB) and also lack ECC support. I don't feel qualified to judge whether one of those might be a deal-breaker for you. I honestly don't know how much RAM CFD Post will use for your applications. Reading the initial post again got me thinking: Is this thread for a "general purpose" workstation that will also run simulations or is it specifically for post-processing? My initial recommendation was for a dedicated post-processing workstation. It severely lacks performance for CFD simulations and does not have enough RAM to run most simulations with this cell count. E.g. Fluent coupled solver in double precision uses 3-4GB of RAM per million cells.

September 3, 2018, 17:42		#5
RedoFromStart New Member Join Date: Dec 2017 Posts: 10 Rep Power: 8	The workstation is specifically for post-processing. Simulations are performed on a cluster. I think that CFD-Post has similar requirements for hardware as Paraview if it helps you with judgement. Is ECC crucial for such task? From what I've read its usually slower than normal RAM.

September 4, 2018, 08:08		#7
JBeilke Senior Member Joern Beilke Join Date: Mar 2009 Location: Dresden Posts: 498 Rep Power: 20	It very much depends on what type of data you have (steady or transient) and what type of postprocessing you want to do: - calculating numbers - section and vector plots - volume rendering - Virtual Reality 512 GB of main memory is probably not too much :-)