HP LeftHand P4000 SAN Solutions - Manual (Page 127)

You should only use a virtual manager if you cannot use a Failover Manager or if manual failover
is preferred for a specific reason. See
“Managers and quorum” (page 119) for detailed information
about quorum, fault tolerance, and the number of managers.
Because a virtual manager is available to maintain quorum in a management group when a storage
system goes offline, it can also be used for maintaining quorum during maintenance procedures.
CAUTION: A virtual manager requires manual intervention to recover quorum and can have
undesirable effects when left running after quorum is recovered. Therefore, HP highly recommends
that you use the Failover Manager rather than the virtual manager.
Requirements for using a virtual manager
It is critical to use a virtual manager correctly. A virtual manager is added to the management
group, but not started on a storage system until the management group experiences a failure and
a loss of quorum. To regain quorum, you start the virtual manager on a storage system that is
operating and in the site that is operational or primary.
Table 44 Requirements for using a virtual manager
Explanation Requirement
Total number of
managers, including the
virtual manager Number of regular
managers running Disaster recovery scenario Use a virtual manager with an even
number of regular managers running
on storage systems.
5 4 Two separate sites with
shared data
3 2 Two storage systems in a
management group
You cannot add a virtual manager after quorum has been lost. The virtual
manager must be added to the management group before any failure occurs. Add a virtual manager when creating
management group.
The virtual manager should run only until the site is restored and data is
resynchronized, or until communication is restored and data is resynchronized. A virtual manager must run only until
the site is restored or communication
is restored.
Correct uses of a virtual manager are shown in Figure 62 (page 128) .
Using a virtual manager 127