Ram per CPU recommendation

AFNI Message Board
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Dear AFNI experts:
I am designing a new neuroimaging cluster and wanted to see if there is a recommended RAM to core recommendation for AFNI. Generally I have purchased systems with 4GB ram per core but the current core count on this new system is about 52-64 cores per node (hyper threading disabled) so I am wanted to get more feedback as that can be a pricy endeavor. Is there a recommended minimum amount of ram/core to optimally run AFNI openmp versions?

Additionally, while I plan on using a docker to run AFNI, I am wondering if there is a strong potential for differing results between AMD based systems and Intel based systems. One of the existing clusters runs on Intel based processors (6230R) and so I wanted to make sure there are no issues in terms of reproducibility if we went with AMD vs Intel for this new cluster.

Thanks in advance for your help.

Ajay

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Hi Ajay,

Actually, 4 GB is often not enough, but it really depends on the resolution of the researchers’s data and the number of time points that they are analyzing. Non-linear registration will often need a bit more RAM, but the RAM usage for the linear regression step of model fitting the time series data varies wildly, and depends heavily on the input data. Sometimes 4 GB is enough, often not.

One thing that is done here is to have some nodes with 4 GB RAM, and some with more. But now the system is getting complicated. Having a separate system with more RAM is also a nice option.

Using different CPUs can have a small effect on the results. One would not expect binary equivalence when jumping between systems, but the results should certainly be close.

Does that seem reasonable?

  • rick
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Hi Rick,
Thanks for the feedback. It makes sense regarding no major differences between AMD vs Intel.

In terms of RAM my question it was not 4GB total per node but 4GB/physical core/node. Since a dual socket node with 52 cores (intel 6230R x2) that would be 208 GB ram which is doable if we need 4GB/core/node. If I go with AMD which is 128 cores (64 cores x2 cpus) this would be 512GB which is much more expensive. I wanted to get a sense if AFNI has any hard or soft rules when it comes to ram per core since we would launch several jobs in parallel so I wouldn’t be using all of the ram to run a single subject. I hope this clarifies my question a bit more.

Best,
Ajay