Every CMIOU has 32 cores of CPU resources. The amount of CPU resources available for each domain varies, depending on the number of CMIOUs that are associated with that domain.
When you first install the operating system instances on a domain, that domain is automatically designated as the global zone. When creating zones on Database Domains, the Database Domain is designated as the global zone, and the zones created on that Database Domain are designated as nonglobal zones.
A certain number of cores are always set aside for the global zone (the Database Domain). The remaining cores in the Database Domain are available for the nonglobal zones (the zones in the Database Domain). The number of cores that are set aside for the global zone varies, depending on the number of CMIOUs that are associated with the domain:
One CMIOU associated with an LDom: 2 cores are reserved for the global zone, and the remaining cores are available for the nonglobal zones.
Two or more CMIOUs associated with an LDom: 4 cores are reserved for the global zone, and the remaining cores are available for the nonglobal zones.
When using the information above, keep in mind that the number of cores that are set aside for the global zone applies only when you are creating zones (nonglobal zones) on that Database Domain. In that case, a certain number of cores are reserved for the Database Domain (the global zone) and the remaining cores are available for the zones on that Database Domain (the nonglobal zones). If you have a Database Domain with no zones, then all the cores are available for that Database Domain.
For each zone that you create, use a minimum of one core per zone. However, depending on the workload that you expect on a zone, a larger number of cores per zone might be preferable, thereby reducing the total number of zones on each compute server. Carefully consider the expected workload on each zone that you create, so that you allot the appropriate number of cores to those zones.