Resource Optimized High Availability (ROHA) is a function in PowerHA® SystemMirror® that automatically and dynamically manages
DLPAR, Enterprise Pool CoD (EPCoD), and On/Off CoD resources. You can configure ROHA with the
Hardware Management Console (HMC), hardware resource provisioning, and cluster tunable
configurations.
Before you use ROHA, you must determine which HMC manages a specific LPAR and any LPARs that you
plan to use in the future. You must also plan for the necessary resources for your applications,
identify your workloads, and your requirements for physical resources (CPU cores, virtual CPUs, and
memory). After you identify all these requirements, you must configure ROHA.
Before using the ROHA function for the first time, you must complete the following steps:
Create an HMC for each LPAR that you identified by running the clmgr add hmc
command.
Create hardware resource provisioning for each application controller that you identified for
your workloads by running the clmgr add roha command.
Note: When you provision
resources for the first time, you must agree or not agree to use On/Off CoD function. If you agree
to use the On/Off CoD function, you are billed for any extra costs. The On/Off CoD agreement is
displayed again only if you did not previously accept the agreement. However, you can use the ROHA
function without accepting the On/Off CoD agreement. In this case, ROHA uses only the DLPAR and
EPCoD operations.
Depending on your environment configuration, you might have to complete the following optional
tasks:
Define HMCs at the site level or node level if your topology requires them.
Change the default HMC tunable values such as retry count, retry delay, or timeout on DLPAR
operations.
Verify the HMC list that is used by the cluster and by each node.
Change the clusters ROHA tunables for DLPAR, Enterprise Pool CoD, and On/Off CoD acquisition and
release operations.
The following figure describes the high-level details for configuring ROHA:Figure 1. ROHA configuration steps
