From the guide:
The expansion capability for each supported RAID level is:
RAID level Expansion capability Maximum disks
NRAID Cannot expand. 1
0, 3, 5, 6 Can add 1–4 disks at a time. 16
1 Cannot expand. 2
10 Can add 2 or 4 disks at a time. 16
50 Can expand the vdisk one RAID-5 sub-vdisk at a 32
time. The added RAID-5 sub-vdisk must contain the
same number of disks as each original sub-vdisk.
IMPORTANT: Vdisk expansion cannot be stopped and can take days to complete, depending on disk
type, RAID level, and other factors. Before starting expansion, see the HP website
http://www.hp.com/support/msa2040/BestPractices.
