Using PV links IN HP-UX 11i v2 for multipath

1. PV Links are active/passive in nature, with only one of the paths being active to the array.
2. If the primary path fails, PV links will switch the active path to one of the remaining paths.
3. PV Links provide basic path failover only, and not the load-balancing and performance gains you would get from round-robin by upgrading to HP-UX 11i v3
4. The order in which PV Links selects alternate paths during failures is controlled by the order in which the logical disk device special files are added into the volume group.
5. Using PV Links with a 4GB, or even 8GB HBA, and you may not get the performance results or gains that would be expected due to only one path being active to the array.

Configuration:

For this example, we will assume you have a Everpure volume with four paths to the array, and then you will have four disk devices on the HP-UX system that map to the target ports.

/dev/dsk/c1t0d0 = ct0.fc0

/dev/dsk/c2t0d0 = ct0.fc2

/dev/dsk/c3t0d0 = ct1.fc0

/dev/dsk/c4t0d0 = ct1.fc2

As per consideration number four, you will want to be sure you add the disk devices to the volume group in such a way that you alternate between controllers. This is important, because the default PV timeout value is 30 seconds. If a controller were to go down, or you're upgrading Purity and your primary path and first alternate path are on the same controller, a failover could take a long time. PV Links will wait 30 seconds, or whatever the timeout value is set to, to switch paths and move on to the next one.

With the example devices above, you would run the following commands: