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Mirroring the root disk in HP-UX is not necessarily as hard as it sounds. There are excellent directions out there. Firstly, go get the PDF from HP titled “When Good Disks Go Bad” (make sure you have the most recent!). This is frequently recommended and you should have it if you don’t already.

Appendix D: Procedures contains detailed instructions on both mirroring PARISC boot disks and Itanium disks. Here is a broad overview to get you prepped:

  • 1. Prepare the disk for LVM. This means using the insf command to add the disk files as appropriate, and using pvcreate to lay down LVM structures.
  • 2. Add the new volume to the root volume group. Use vgextend to add the new disk to the volume group.
  • 3. Make the disk bootable. This is a hairy part. You have to copy the proper data from the original disk, and so forth. Follow the directions closely.
  • 4. Mirror the logical volumes on the first disk to the new one. This has to be done in a specific order or it will fail. It’s not hard, just time consuming.
  • 5. Update system data with new boot information. This involves configuring the machine to boot with the new disk.

Setting up Itanium boot mirrors requires a few additional steps: the disk must be partitioned into three parts: 1) EFI boot partition; 2) HP-UX root disk data; and 3) HP Service Partition. The second partition is equivalent to the entire disk in a PARISC system. The first partition (EFI boot) is like a mini-disk that contains all of the data needed to boot HP-UX.

The last partition – the HP service partition – is not configured unless you copy it from the original source. If you do not do this, you do not actually have a service partition – which could be a nasty surprise when you need it!