Veritas Volume Manager (VxVM) on AIX 5.3

I'm a fan of VxVM, I've use over many years. But I did get to a problem that stumped me recently.

I was unable to initialise the disks on AIX, I would get a permission denied error.

aix53# /usr/lib/vxvm/bin/vxdisksetup -if DS4700-0_1 format=aixdisk
/dev/hdisk3: Permission denied

Resolution.
The DS4700 storage must use AIX multipath MPIO and that needs the right reserve policy. (VxVM's DMP only sees a single path)

aix53# chdev -l hdisk3 -a reserve_policy=no_reserve


Config
Aix 5.3 TL8 SP2
DS4700 Firmware 9.6x
VxVM 5, MP1, Rolling Patch5, HotFix 5