Although the official HP position is that the only kosher way of doing this is by reigniting the server and modifying the sizes in doing so;Increasing / and /stand online is very easy if you have mirror disk installed. We have been doing this for years on large production systems without a second of downtime and without any problems.
For example, to extend your first contiguous volume on your first disk, break the mirrors for any volume that follow on this disk, you then have your first volume living alone on the first disk and all the others on the second one.
At this point, you still can't extend that volume because it's mirrored on the second disk: Break that mirror, leaving all your volumes unmirrored.
You can now extend that volume on the first disk as it lives alone on that disk.
Now, remirror the other volumes from the second disk to the first.
Your first disk is now done.
To do a cleaner job, break all the mirrors on the second disk and remirror everything back.
Voila... You are done.
