10.45 How many volumes can be added to a volumeset? We are going to attempt to add 32 more disks to ours (16 primary and 16 mirrors) bringing our total from 96 (48 primary, 48 mirrors) to 128 (64 primary, 64 mirrors).
From Scott McClellan of HP:
The maximum number of volumesets is 255.
The maximum number of volumes in one volumeset is 255.
The maximum number of volumes (TOTAL) on a given system is 255 (511 with MPE/iX 6.5)
A mirrored disk requires (obviously) two volumes, so the maximum number of mirrored pairs is < 128 (note: you cannot mirror the system volumeset).