Pros and Cons of moving from 4 cores on each compute to 2 cores

[sharda]

Good day,

I was seeking help to research what the pros and cons will be to decrease our footprint of SAS by 50%. Currently we have two compute servers (Linux) with 4 cores on each. If we were to move to an environment with 2 cores on each what are the pros and cons to this?

Thanks,
Sharda

[nhvdwalt]

Do you have any performance monitoring in place now ? What is your current utilisation ?

[SASKiwi]

I would suggest that running two compute servers with only 2 cores each would be counterproductive. You would be better off moving to one compute server with four cores as this will remove the overhead of distributing the workload across two servers.

As @nhvdwalt has already indicated, what is the CPU load on your current environment? If you are regularly maxing out your CPU then you will adversely impact performance with the downgrade. On the other hand if you never reach 50% of your CPU usage then you will be impacted much less.

[JuanS_OCS]

100% agreed with @SASKiwi. Also, if you are working with SAS 9.4 or planning to upgrade/migrate to 9.4, please remember that SAS Foundation has a pre-requisite of minimum of 4 cores in SAS 9.4.

Answering to your question, I personally do not see any Pro, except a few less euros per machine.... but probably the cost of getting the 2 core machines will be already higher. For all the rest of considerations I have on mind, I can only see Cons.

I feel curious: does the speed (Ghz) of each core increase, decrease or stays the same?

[Kurt_Bremser]

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@JuanS_OCS wrote:

Also, if you are working with SAS 9.4 or planning to upgrade/migrate to 9.4, please remember that SAS Foundation has a pre-requisite of minimum of 4 cores in SAS 9.4.

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Interesting. I'm running 9.4 very comfortably on just two POWER8 cores (8 threads with SMT enabled).

[JuanS_OCS]

The flavour of the core matters @Kurt_Bremser. And the objective is to be able to create enough threads. Hence, it is easier and more standard the explanation on the system requirements for SAS foundation. It really avoids all kind of troubles to non-techy speakers.

If your cores can thread enough, you are good to go.  

Not every one has got POWER8 cores/cpus, Kurt 🙂 

[Kurt_Bremser]

Even SAS representatives have problems grasping the difference between physical CPUs, cores, and thread execution units. One of them once thought that we were violating the license agreement when he saw 4 "CPU"s reported in topas (which shows every thread execution in parallel). I had to finally show him the server with the two POWER5 chips (back then they were not multicore in a modern sense, you could only run one single-threaded app per CPU, and only MT apps were able to use the SMT feature).