If you want I/O Domains set up on your Oracle SuperCluster, either at the time of the initial installation or afterwards, you must have at least one Root Domain set up at the time of the initial installation. I/O Domains can then be created from these Root Domains.
A certain amount of memory resources are always reserved for each Root Domain, depending on which domain is being used as a Root Domain in the domain configuration and the number of IB HCAs and 10GbE NICs that are associated with that Root Domain:
• The last domain in a domain configuration:
• 32 GB of memory reserved for a Root Domain with one IB HCA and 10GbE NIC
• 64 GB of memory reserved for a Root Domain with two IB HCAs and 10GbE NICs
• Any other domain in a domain configuration:
• 16 GB of memory reserved for a Root Domain with one IB HCA and 10GbE NIC
• 32 GB of memory reserved for a Root Domain with two IB HCAs and 10GbE NICs
The remaining memory resources allocated with each Root Domain are parked in the memory repository, which can then be used by I/O Domains.
Note – For more information on the number of IB HCAs and 10GbE NICs associated with each domain, refer to the Oracle SuperCluster M8 and SuperCluster M7 Overview Guide.
The memory repository contains resources not only from the Root Domains, but also any parked resources from the dedicated domains. Whether memory resources originated from dedicated domains or from Root Domains, once those resources have been parked in the memory repository, those resources are no longer associated with their originating domain. These resources become equally available to I/O Domains.
In addition, the memory repository contains parked resources only from the compute server that contains the domains providing those parked resources. In other words, if you have two compute servers and both compute servers have Root Domains, there are two sets of memory repositories, where each compute server has its own memory repository with parked resources.
For example, assume you have four domains on your compute server, with three of the four domains as Root Domains. Assume each domain has the following:
• One IB HCA and one 10GbE NIC
• 480 GB of memory
In this situation, the following memory resources are reserved for each Root Domain, with the remaining resources available for the memory repository:
• 32 GB of memory reserved for the last Root Domain in this configuration. 448 GB of memory available from this Root Domain for the memory repository.
• 16 GB of memory reserved for the second and third Root Domains in this configuration.
• 464 GB of memory available from each of these Root Domains for the memory repository.
• A total of 928 GB of memory (464 x 2) available for the memory repository from these two Root Domains.
A total of 1376 GB of memory (448 + 928) are therefore parked in the memory repository and are available for the I/O Domains.