User's Manual

seized usage rights in order to stop using temporary capacity. If this happens, the seized usage
rights are no longer available for the failover activation.
By specifying the use of temporary capacity on failover activation, you guarantee that the core
activations needed for failover will occur. The total temporary capacity consumption across the
group remains the same, even though the temporary capacity might be consumed on the failover
server instead of on the original server.
If, for some reason, it is important to keep the temporary capacity usage to a particular server,
you can manually deactivate the temporary capacity-consuming cores before doing the failover
activations, and then reactivate the temporary capacity usage after the failover activations. For
similar reasons, it might also be important to make sure other activations are not occurring
simultaneously during a failover sequence.
Other Considerations
Rights seizure can be used as part of an automatic failover system, but be sure that resources are
seized appropriately and in a manner that does not cause problems when the problem is corrected.
The Instant Capacity software determines that the partition is down based on whether the ping
command is unsuccessful for the partition. In some circumstances, ping might be unsuccessful
but the system remains functional (for example, if a network connection is interrupted). In this
case, rights seizure may be inappropriate and leave workloads without the necessary resources.
There are no restrictions regarding the type of environment from which rights were seized. Rights
that are seized from either an nPartition environment or a virtual partition environment can be
deployed on any member of the GiCAP group, regardless of the target environment type.
Additional HA Solutions
Although rights seizure is the main method used in a GiCAP high availability (HA) scenario,
there are additional methods and configurations allowing GiCAP to provide you with HA
solutions:
• You can use GiCAP to move capacity from one or more nonproduction servers, such as test
servers, during a failover situation. You have a set of standby servers that are part of a group
and can pool their resources to provide failover capability.
• You can combine GiCAP with temporary capacity. If you have a set of nonproduction servers,
and some of those servers contain temporary capacity, temporary capacity from the entire
group is made available during a failover situation. Temporary capacity is not seizable, so
any HA solution involving temporary capacity must ensure that it is available on the standby
server.
• Systems with full usage rights can also be a part of a GiCAP group and can be used as donor
systems, contributing usage rights to the group and allowing additional activations on
member systems with Instant Capacity components.
Summary of Rights Seizure
The following summarizes usage rights seizure on GiCAP systems:
• iCAP can seize usage rights from an unavailable server.
Usage rights can be seized from a group member even if the entire server is unavailable. In
this case, usage rights expire after 10 days and revert to the original partition.
• Only core usage rights can be seized.
While GiCAP allows migration of all types usage rights between member servers (cores,
cells, and memory), seizure from a failed partition is only for core usage rights. If cell or
memory usage rights are needed, partitioning tools such as the parmodify command can
be used either remotely or on an accessible partition to remove one or more cells from the
unavailable partition, making usage rights available. Changing the use-on-next-boot (UONB)
124 Global Instant Capacity