HyperSwap for PowerHA SystemMirror concepts

The HyperSwap® function in PowerHA® SystemMirror® Enterprise Edition 7.1.2, or later, enhances application availability for storage errors by using IBM® DS8000® metro mirroring. If you use the HyperSwap function in your environment, your applications stay online even if errors occur on the primary storage because PowerHA SystemMirror 7.1.2, or later, transparently routes the application I/O to an auxiliary storage system.

The HyperSwap function uses a model of communication, which is called in-band, that sends the control commands to a storage system through the same communication channel as the I/O for the disk. The HyperSwap function supports the following types of configurations:
Traditional Metro Mirror Peer-to-Peer Remote Copy (PPRC)
The primary volume group is only visible in the primary site and the auxiliary volume group is only visible in the auxiliary site.
HyperSwap
The primary and auxiliary volume group are visible from the same node in the cluster.
You typically configure the HyperSwap function to be used in the following environments:
Single node environment
A single compute node is connected to two storage systems that are in two sites. This HyperSwap configuration is ideal to protect your environment against simple storage failures in your environment.
Multiple site environment
A cluster has multiple nodes that are spread across two sites. This HyperSwap configuration provides high availability and disaster recovery for your environment.
Mirror groups in HyperSwap for PowerHA SystemMirror represent a container of disks and have the following characteristics:
  • Mirror group contain information about the disk pairs across the site. This information is used to configure mirroring between the sites.
  • Mirror groups can contact a set of logical volume manager (LVM) volume groups and a set of raw disks that are not managed by the AIX® operating system.
  • All the disks devices that are associated with the LVM volume groups and raw disks that are part of a mirror group are configured for consistency. For example, the IBM DS8800 views a mirror group as one entity regarding consistency management during replication.
  • The following types of mirror groups are supported:
    User mirror group
    Represents the middleware-related disk devices. The HyperSwap function is prioritized internally by PowerHA SystemMirror and is considered low priority.
    System mirror group
    Represents critical set of disks for system operation, such as, rootvg disks and paging space disks. These types of mirror groups are used for mirroring a copy of data that is not used by any other node or site other than the node that host these disks.
    Repository mirror group
    Represents the cluster repository disks of that are used by Cluster Aware AIX (CAA).