HP support web site is a bit like tangled mess to me, it always take a ton of time to find what I'm looking for. There is a dramatic scarcity of really useful how-to type documentation on HP-UX administration. I don't deal with HP-UX very frequently and so I get rusty around certain areas and so need to check the documentation every so often. Replacing failing drives in mirrored volumes is one the chores that you don't do very often and so there is always a need for a handy manual on this topic. Here is a very good one document from HP that might save you a bit of time, just as did for me:

When Good Disks Go Bad