High availability in case of adapter or power supply failure

To protect against adapter or power supply failure, depending on your requirements, do one or more of the following.

• Use two adapters, located in the same or different chassis. Locating the adapters in different chassis protects against losing both adapters if there is a power supply failure in one chassis.
• Use two adapters, attaching at least one disk to each adapter. This protects against a failure at either adapter (or power supply if adapters are in separate cabinets) by still maintaining a quorum in the volume group, assuming cross-mirroring (copies for a logical partition cannot share the same physical volume) between the logical volumes on disk A (adapter A) and the logical volumes on disk B (adapter B). This means that you copy the logical volumes that reside on the disks attached to adapter A to the disks that reside on adapter B and also that you copy the logical volumes that reside on the disks attached to adapter B to the disks that reside on adapter A as well.
• Configure all disks from both adapters into the same volume group. This ensures that at least one logical volume copy remains intact in case an adapter fails, or, if cabinets are separate, in case a power supply fails.
• Make the volume group a nonquorum volume group. This allows the volume group to remain active as long as one Volume Group Descriptor Area (VGDA) is accessible on any disk in the volume group.
• If there are two disks in the volume group, implement cross-mirroring between the adapters. If more than one disk is available on each adapter, implement double-mirroring. In that case, you create a mirrored copy on a disk that uses the same adapter and one on a disk using a different adapter.