If you have a guest that's actively processing application traffic but needs additional CPU cores, you can increase the number of cores that are currently allocated to the guest. To do this, you'll need to temporarily disable the guest while you add cores, and then re-deploy the guest.
When you increase the Cores per Guest value on a guest, the new value must be within the total number of unused CPU cores on the system; the system never allocates more cores to a guest than the number of cores still available on the system.
For example, suppose you have three guests on a 12-core system, with this core allocation:
|Guest Name||Current Cores per Guest|
With a total allocation of 10 out of 12 cores allocated on the system, this means that only two cores remain unused and available to add to a guest. Therefore, if you try to add four additional cores to Guest C (from 2 to 6), the system displays a message that you are exceeding the number of cores available on the system. In this case, the maximum number of cores that you can allocate to Guest C is 4.
A potential workaround for this would be to first decrease the number of cores allocated to Guest A, to free up additional cores for Guest C.
You can determine the number of cores still available on the system by logging in to the BIG-IP Configuration utility and displaying the vCMP Guest List screen.
If you have a running vCMP guest, and you decide that you need to allocate more CPU cores to the guest than what was originally allocated, you can increase the number of cores for the guest.
To do this, you'll first need to set the guest state from Deployed to Configured. Once you've increased the number of cores for the guest, you can set the guest back to the Deployed state.
Note that when switching between guest states, the process can take several minutes for the guest to shut down cleanly and restart again.