When the OS is installed 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 a domain – 2 cores are reserved for the global zone, and the remaining cores are available for the nonglobal zones.
Two or more CMIOUs associated with a domain – 4 cores are reserved for the global zone, and the remaining cores are available for the nonglobal zones.
A Database Domain with no zones – 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.