Since you don't mention your hardware, I'll speak in general terms. To do this correctly, you need to protect your self from more than simply a disk failure. You need to be able to tolerate a controller failure or a cable failure (or accidental disconnection) as well.
I'll use a D-3xx box with internal hot-plug drives as an example. Let's say you are booting from a 4GB disk on the internal HVD SCSI drive. To mirror correctly, you need to have an external drive enclosure (e.g. a Jamaica), a second HVD SCSI controller, a second (ideally) identical 4GB drive, cables, and terminator(s). You of course also must install the Mirror/UX software.
This fully protects and mirrors your data. If possible, avoid internal disks which are not hot-pluggable. For example, none of my K-box use internal drives instead I boot from external drives - this way I can replace a drive without shutting down the box.
You can, of course, simply put in a second drive (with a different SCSI ID) on your current bus but that only protects from a drive failure.
Once the hardware is configured, the actual mirroring is simple.
Clay's suggestion in addressing the hardware issues are perfect.
I have a script here slightly different with a little less typing to do the logical volume mirroring.
# pvcreate -f -B /dev/rdsk/cXtXdX # vgextend /dev/vg00 /dev/rdsk/cXtXdX # mkboot /dev/rdsk/cXtXdX # mkboot -a "hpux -lq(;0)/stand/vmunix" /dev/rdsk/cXtXdX # lvlnboot -R # for LVOL in /dev/vg00/lv* > do > echo $LVOL > lvextend -m 1 $LVOL > done #
One other suggestion is to do a make_recovery tape on completion. This will ensure that you have an operating system of your system on a bootable tape. we use this procedure.
# make_tape_recovery -x inc_entire=vg00 -I -v -a /dev/rmt/0mn (assuming /dev/rmt/0m is you DDS tape drive)
