Managing Serviceguard Sixteenth Edition, March 2009

you using a SCSI cluster lock or dual Fibre
Channel cluster lock).
Maximum supported value: 300 seconds
(300,000,000 microseconds).
If you enter a value greater than 60 seconds
(60,000,000 microseconds), cmcheckconf and
cmapplyconf will note the fact, as confirmation
that you intend to use a large value.
Minimum supported values:
• 3 seconds for a cluster with more than one
heartbeat subnet.
• 8 seconds for a cluster with more than one
heartbeat using CFS (see “Creating a Storage
Infrastructure with Veritas Cluster File
System (CFS)” (page 233) for more
information about CFS; see also the
“Considerations for CVM” under
HEARTBEAT_IP earlier in this section).
• 14 seconds for a cluster that has only one
Ethernet heartbeat LAN
• 22 seconds for a cluster that has only one IP
over Infiniband (IPoIP) heartbeat LAN
With the lowest supported value of 3 seconds, a
failover time of 4 to 5 seconds can be achieved.
NOTE: The failover estimates provided here
apply to the Serviceguard component of failover;
that is, the package is expected to be up and
running on the adoptive node in this time, but
the application that the package runs may take
more time to start.
Keep the following guidelines in mind when
deciding how to set the value.
Guidelines: You need to decide whether it's more
important for your installation to have fewer (but
slower) cluster re-formations, or faster (but
possibly more frequent) re-formations:
• To ensure the fastest cluster re-formations,
use the minimum value applicable to your
cluster. But keep in mind that this setting
152 Planning and Documenting an HA Cluster