Switched disks

A switched disk is an independent disk pool that is controlled by a device cluster resource group and can be switched between nodes within a cluster. When switched disks are combined with IBM® i clusters technology, you can create a simple and cost effective high availability solution for planned and some unplanned outages.

The device cluster resource group (CRG) controls the independent disk pool which can be switched automatically in the case of an unplanned outage, or it can be switched manually by with a switchover.

A group of systems in a cluster can take advantage of the switchover capability to move access to the switched disk pool from system to system. In this environment, an independent disk pool can be switchable when it resides on a switchable device. A switchable device can be an external expansion unit (tower), an IOP on the bus shared by logical partitions, or an IOP that is assigned to an I/O pool. Hardware that does not have a physical IOP has a virtual logical representation of the IOP.