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Team, I'm looking for clarification on the virtual machine CPU requirements for ISE
The ISE 2.4 installation guide states the following as CPU requirements for Medium Virtual Appliance:
Clock Speed—2.0 GHz or faster
Number of Cores
SNS 3500 Series Appliance:
`Medium—16 processors (8 cores with hyperthreading enabled
But later in the document it says:
Table 3. VM Appliance Specifications for a Production Environment
Medium VM Appliance (based on SNS-3595)
8 total cores (at 2.0 GHz or above) or a total minimum CPU allocation of 16000 MHz.
The "OR" in the above table is what is confusing.
Question: If the host is running 3.0Ghz clock-speed procs, will TAC support them if they run only 6 cores to achieve the >16000Mhz CPU reservation? This would contradict the core-count requirement of 8 total cores in the red-highlighted section above.
This is a great question. In general when using multithreaded application more cores is better. Here is a reference article I found that would explain how it works.
I think this is a bug in the documentation. I will reach out to the relevant team.
Thank you for pointing this out.
The hyper threading thing is just confusing because it has nothing to do with the VM setup itself. If you load up the new OVAs Cisco provide a 3515 will be provisioned with 12 CPUs and 12,000 MHz of reservations and the 3595 will be setup with 16 CPUs and 16,000 MHz of reservations.
Now if the ESX host server has hyper threading enabled the 12 CPUs will only consume 6 CPUs and the 16 CPUs will only consume 8 CPUs, but this has absolutely nothing to do with the VM itself. The VM will always think it has 12 or 16 CPUs.
Also, if you don't put the right number of CPUs in the VM, ISE won't detect the platform correctly and allocate resources. That was the whole issue with the OVAs since 2.2. The OVAs had the wrong number of CPUs causing ISE to not detect the correct platform.
VMware ESXi - More cores or faster cores? : vmware is a good read. Certain tasks in ISE are more CPU-bound; e.g. massy re-profiling and during ISE service initialization. Best to monitor the work loads of various ISE nodes and adjust accordingly.