Installation manual

Adding a Managed Volume
Selecting a VPU (optional)
CLI Storage-Management Guide 9-45
Selecting a VPU (optional)
The next step in configuring a volume is to choose its Virtual-Processing Unit (VPU).
A VPU is a virtual CPU that can fail over from one chassis to another in a redundant
configuration. Every volume type, including managed and direct, runs on a particular
VPU. The namespace software chooses a default VPU if you do not explicitly choose
one.
VPUs, maximum volumes per platform, maximum namespaces per platform, and the
algorithm for default-VPU assignment were discussed in the chapter about direct
volumes; recall “Selecting a VPU (optional)” on page 8-19.
Assigning the Volume to a VPU
As you would in a direct volume, use the vpu command to assign the volume to a
VPU. Do this before the volume is enabled; once the volume is enabled (below), you
cannot re-assign it to another VPU without entirely rebuilding it.
For example, the following command sequence assigns the current volume,
“medarcv~/rcrds,” to VPU 2:
bstnA6k(gbl)# namespace medarcv
bstnA6k(gbl-ns[medarcv])# volume /rcrds
bstnA6k(gbl-ns-vol[medarcv~/rcrds])# vpu 2
bstnA6k(gbl-ns-vol[medarcv~/rcrds])# ...
The default-VPU assignment rules can artificially reduce the maximum number of
namespaces for the host switch. Once the volume is enabled, its VPU assignment is
permanent. This is a much bigger problem for managed volumes than it is for direct
volumes. Read about VPUs carefully before using the default-VPU assignment.