Adding a second workstation

Bazinga · March 7, 2017, 03:11

Dear all,

Last year we bought a new computer for our CFD LES (mainly incompressible flows).

This year we want to add another one for two purposes:

1. Being able to run larger cases on both computers at the same time on all cores.
2. Running simulations on both computers independently to speed up the process for multiple "small" simulations.

The old computer consists of:
INTEL Xeon E5-2680 V3 2500MHz 30M Cache 12Core with 16*16GB DDR4 2133.

My three questions regarding our new purchase are:

1. How should I connect those computers in terms of hardware? Do I need something like Infiniband?

2. Does it matter if the new computer has different CPUs /RAM or should I go buy the same computer again?

3. I am happy about any helpful comments as I am really no expert in this field.

Thanks in advance.

flotus1 · March 7, 2017, 03:49

1. Gigabit ethernet (or 10G ethernet if the motherboards came with it) might be sufficient, at least you can give it a try. Infiniband hardware can still be added later if you should observe poor scaling when spanning a job across both machines. There are a few tutorials here on how to set it up NEW TUTORIAL: setting 2-node cluster with infiniband (WIN7)
2. You don't need the exact same specifications, so there is no need to buy old hardware for your new workstation, especially if you intend to use it as a single workstation aswell. If you buy a faster machine now, parallel jobs will be limited by the execution speed of the slower cores on the older machine, not utilizing the full capacity of the faster machine. It is possible to avoid this issue with clever load balancing, e.g. assigning smaller partitions to the slower cores.
3. anything particular

Bazinga · March 7, 2017, 04:07

Dear Alex,

thanks for the fast reply! Makes perfect sense to me

The mobo is capable of 10G ethernet so I will use this one first.

From another thread I saw that you recommended Xeon E5-2687w v4, which come as 2*12 cores.
Would you recommend a CPU with 2*14 or 2*16 cores, or is 2*12 the best "bang for the buck" at the moment?
Do you have a recommendation for 2*16 or 2*14?

Vielen Dank nochmal.

flotus1 · March 7, 2017, 04:22

The best "bang for the buck" in my opinion is the Xeon E5-2650 v4 (12 cores, 2.5GHz all core turbo). It might just be a bit too slow if you can afford more.
In terms of performance, the E5-2687W v4 (12 cores, 3.2GHz) is the obvious choice. If you favor more cores instead of fast cores, the E5-2690 v4 (14 cores, 2.9GHz) or even the E5-2683 v4 (16 Cores, 2.5GHz) are interesting options.

Bazinga · March 7, 2017, 04:31

Again, thank you so much for the fast and crystal clear answer. Enjoy your day.

March 7, 2017, 03:11	Adding a second workstation	#1
Bazinga Senior Member Join Date: Jun 2012 Location: Germany, Bochum Posts: 230 Rep Power: 16	Dear all, Last year we bought a new computer for our CFD LES (mainly incompressible flows). This year we want to add another one for two purposes: 1. Being able to run larger cases on both computers at the same time on all cores. 2. Running simulations on both computers independently to speed up the process for multiple "small" simulations. The old computer consists of: INTEL Xeon E5-2680 V3 2500MHz 30M Cache 12Core with 16*16GB DDR4 2133. My three questions regarding our new purchase are: 1. How should I connect those computers in terms of hardware? Do I need something like Infiniband? 2. Does it matter if the new computer has different CPUs /RAM or should I go buy the same computer again? 3. I am happy about any helpful comments as I am really no expert in this field. Thanks in advance.

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March 7, 2017, 03:49		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,426 Rep Power: 49	1. Gigabit ethernet (or 10G ethernet if the motherboards came with it) might be sufficient, at least you can give it a try. Infiniband hardware can still be added later if you should observe poor scaling when spanning a job across both machines. There are a few tutorials here on how to set it up NEW TUTORIAL: setting 2-node cluster with infiniband (WIN7) 2. You don't need the exact same specifications, so there is no need to buy old hardware for your new workstation, especially if you intend to use it as a single workstation aswell. If you buy a faster machine now, parallel jobs will be limited by the execution speed of the slower cores on the older machine, not utilizing the full capacity of the faster machine. It is possible to avoid this issue with clever load balancing, e.g. assigning smaller partitions to the slower cores. 3. anything particular

March 7, 2017, 04:07		#3
Bazinga Senior Member Join Date: Jun 2012 Location: Germany, Bochum Posts: 230 Rep Power: 16	Dear Alex, thanks for the fast reply! Makes perfect sense to me The mobo is capable of 10G ethernet so I will use this one first. From another thread I saw that you recommended Xeon E5-2687w v4, which come as 212 cores. Would you recommend a CPU with 214 or 216 cores, or is 212 the best "bang for the buck" at the moment? Do you have a recommendation for 216 or 214? Vielen Dank nochmal.

March 7, 2017, 04:22		#4
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,426 Rep Power: 49	The best "bang for the buck" in my opinion is the Xeon E5-2650 v4 (12 cores, 2.5GHz all core turbo). It might just be a bit too slow if you can afford more. In terms of performance, the E5-2687W v4 (12 cores, 3.2GHz) is the obvious choice. If you favor more cores instead of fast cores, the E5-2690 v4 (14 cores, 2.9GHz) or even the E5-2683 v4 (16 Cores, 2.5GHz) are interesting options.

March 7, 2017, 04:31		#5
Bazinga Senior Member Join Date: Jun 2012 Location: Germany, Bochum Posts: 230 Rep Power: 16	Again, thank you so much for the fast and crystal clear answer. Enjoy your day.