When you replace a drive on one of these, mdisk arrays do not auto-rebuild.
If the GUI fix procedures go away, or never show up, or whatever causes the replacement drive to not get included as a new drive in the mdisk, you can do this manually.
First, look for the candidate or spare drive you want to use.
lsdrive | grep -v member
Then, make sure that drive ID is a candidate:
chdrive -use candidate 72
Then, find the missing member:
lsarraymember mdisk1 | grep -v exact
Then, set the new drive to use that missing member ID:
charraymember -member 31 -newdrive 72 mdisk1
You can watch the progress of the rebuild: