HP Integrity Virtual Machines 4.2: Installation, Configuration, and Administration

• Guest OS boot disks can be of any backing-store type; however, shared storage, the storage
used by the application on the guest that is accessed from more than one virtual machine,
can be only whole disk or SLVM.
• DVD and tapes devices can be defined on one or more VM and are typically ignored by
Serviceguard. For additional information about excluding a Device from probing, see the
Managing Serviceguard manual.
11.2.9 Additional Considerations for VMs as Serviceguard Nodes Configurations
Serviceguard clusters rely on a cluster daemon process called cmcld that determines cluster
membership by sending heartbeat messages to other cmcld daemons on other nodes within
the cluster. The cmcld daemon runs at a real-time priority and is locked in memory. Along with
handling the management of Serviceguard packages, cmcld also updates a safety timer within
the kernel to detect kernel hangs, checks the health of networks on the system and performs local
LAN failovers. Status information from cmcld is written to the node's system log file.
In VMs as Serviceguard Nodes configurations, there are some situations where VMs defined
with multiple vCPUs, or a single vCPU with insufficient entitlement, can potentially experience
cmcld run-time delays under heavy processing load conditions. If the run-time delay is longer
than the configured cluster NODE_TIMEOUT value (that is., the time after which a node might
decide that the other cluster node has become unavailable), cmcld triggers a cluster reformation
just as if a node had failed. However, because no node has actually failed, the cluster reforms
potentially with the same number of nodes it originally had before the cmcld run delay was
reported depending on the length of the run delay.
Other factors that might contribute to this situation include vCPU processing entitlement
percentages and the number of vCPUs assigned per VM as they relate to HP-UX kernel time-slice
processing. Cmcld run delays can be identified by the following warning reported in the system
log file:
[date/time VM name] cmcld [PID]: Warning: cmcld process was unable to
run for the last x.yz seconds
HP recommends that you install the latest Fair Share Scheduler patches on all VM Hosts to
minimize the possibility of encountering this problem and triggering false cluster reformations.
Another option is to increase the Serviceguard cluster NODE_TIMEOUT to a value larger than
the run delay reported in the syslog file. The default value for this cluster parameter is 2 seconds,
and the maximum recommended value is 30 seconds. However, for most installations, a setting
between 5–8 seconds is appropriate.
NOTE: Increasing the NODE_TIMEOUT value causes the cluster to take longer to react to an
actual node failure.
11.2.10 Creating the VMs as Serviceguard Nodes Configuration
This section assumes that you have installed the appropriate HP-UX operating environment and
Integrity VM software on the VM Hosts and that the Serviceguard software has been installed
on any physical nodes. The interrelated configuration of the physical hosts, VM Hosts, virtual
machine, Serviceguard cluster, and Serviceguard packages dictates that all components be
configured and created in a particular sequence.
The following process is one of many ways to create a VMs as Serviceguard Packages
configuration. Note, you can use the Virtualization Manager or the Serviceguard Manager as
alernatives when appropriate.
On the VM Hosts and the physical Serviceguard Nodes, perform the following steps:
1. Create the network configuration on each of the VM Hosts and physical Serviceguard Nodes.
192 Using HP Serviceguard with Integrity VM