Multipath I/O

View Multipath I/O (MPIO) information for client logical partitions.

Multiple virtual SCSI or virtual fibre channel adapters in a client logical partition can access the same disk through multiple Virtual I/O Server logical partitions. This section describes a virtual SCSI multipath device configuration. If correctly configured, the client recognizes the disk as a multipath device. If you are using PowerVM™ Active Memory™ Sharing technology (or shared memory), you can also use a multipath configuration to allow two paging VIOS logical partitions to access common paging space devices.

MPIO is not available for IBM® i client logical partitions. Instead, you must use mirroring to create redundancy. For more information, see Mirroring for client logical partitions.

Not all virtual SCSI devices are capable of MPIO. To create an MPIO configuration, the exported device at the Virtual I/O Server must conform to the following rules:

• The device must be backed by a physical volume. Logical volume-backed virtual SCSI devices are not supported in an MPIO configuration.
• The device must be accessible from multiple Virtual I/O Server logical partitions.
• The device must be an MPIO-capable device.
  Note: MPIO-capable devices are those that contain a unique identifier (UDID) or IEEE volume identifier. For instructions about how to determine whether disks have a UDID or IEEE volume identifier, see Identifying exportable disks.

When setting up an MPIO configuration for virtual SCSI devices on the client logical partition, you must consider the reservation policy of the device on the Virtual I/O Server. To use an MPIO configuration at the client, none of the virtual SCSI devices on the Virtual I/O Server can be reserving the virtual SCSI device. Ensure the reserve_policy attribute of the device is set to no_reserve.

Failover is the only supported behavior for MPIO virtual SCSI disks on the client logical partition.