Intel 7xx Servers manual High Availability Performance, Switchable IASP’s, Workload Description

Chapter 21. High Availability Performance

The primary focus of this chapter is to present data that compares the effects of high availability scenarios using different hardware configurations. The data for the high availability test are broken down into two different categories which include Switchable IASP’s, and Geographic Mirroring.

High Availability Switchable Resources Considerations

Switchable IASPs are the physical resource that can be switched between systems in a cluster. A switchable IASP contains objects, the directories and libraries that contain the objects, and other object attributes such as authorization and ownership attributes.

Geographic Mirroring is a subfunction of cross-site mirroring (XSM) that generates a mirror image of an IASP on a system, which can be geographically distant from the originating site.

21.1 Switchable IASP’s

There are three different switchover/failover scenarios that can occur in a switchable IASP environment.

Switchover: A cluster event where the primary database server or application server switches over to a backup system due to a manual intervention from the cluster management interface.

Failover: A cluster event where the primary database server or application server automatically switches to a backup system due to the failure of the primary server

Partition: A cluster event where communication is lost between one or more nodes in the cluster and a failure of the lost nodes cannot be confirmed. When a cluster partition condition is detected, cluster resource services limits the types of actions that you can perform on the nodes in the cluster partition.

NOTE: Failover performance is similar to switchover performance and therefore the workload was only run for switchover performance.

Workload Description

Switchable IASP’s using hardware resources

yActive Switchover - For an active switchover, the workload consists of bringing up a database workload on the IASP until the desired number of jobs are running on the system. Once the workload is stabilized the CHGCRGPRI(Change Cluster Resource Group Primary) command is issued from the command prompt. Switching time is measured from the time the CHGCRGPRI command is issued on the primary system until the new primary system’s IASP is available. The CHGCRGPRI command ends all the jobs in the susbsystems that are using the IASP and thus time depends heavily on how many jobs are active on the IASP at the time the command is issued.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
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