• Identify the LUN to extend on DS8000, and update the size: chfbvol -cap <new_size_GB> <LUN_ID>

dscli> chfbvol -cap 100 -quiet 5125

• On the target host, check if the LUN size has increased, else wait 30s, and try again:

# bootinfo -s hdisk0
Or
# getconf DISK_SIZE /dev/hdisk0

• Update the VG size, also possible on rootvg, but not on LUN containing an active paging space (you can do it by moving paging on another disk during this operation):

# chvg -g datavg