Managing HP Serviceguard for Linux Ninth Edition, April 2009

written so that they can detect such a restart. This is the same application design required
for restart after a normal system crash.
In the event of a LAN interface failure, bonding provides a backup path for IP messages.
If a heartbeat LAN interface fails and no redundant heartbeat is configured, the node
fails with a reboot. If a monitored data LAN interface fails, the node fails with a reboot
only if node_fail_fast_enabled (described further under “Configuring a Package: Next
Steps” (page 144)) is set to yes for the package. Otherwise any packages using that
LAN interface will be halted and moved to another node if possible (unless the LAN
recovers immediately; see “When a Service or Subnet Fails, or a Dependency is Not
Met” (page 67)).
Disk monitoring provides additional protection. You can configure packages to be
dependent on the health of disks, so that when a disk monitor reports a problem, the
package can fail over to another node. See “Creating a Disk Monitor Configuration”
(page 220).
Serviceguard does not respond directly to power failures, although a loss of power to
an individual cluster component may appear to Serviceguard like the failure of that
component, and will result in the appropriate switching behavior. Power protection is
provided by HP-supported uninterruptible power supplies (UPS).
Responses to Package and Service Failures
In the default case, the failure of the package or of a service within a package causes
the package to shut down by running the control script with the stop parameter, and
then restarting the package on an alternate node. A package will also fail if it is
configured to have a dependency on another package, and that package fails.
You can modify this default behavior by specifying that the node should halt (system
reset) before the transfer takes place. You do this by setting failfast parameters in the
package configuration file.
In cases in which package shutdown might hang, leaving the node in an unknown
state, failfast options can provide a quick failover, after which the node will be cleaned
up on reboot. Remember, however, that a system reset causes all packages on the node
to halt abruptly.
The settings of the failfast parameters in the package configuration file determine the
behavior of the package and the node in the event of a package or resource failure:
• If service_fail_fast_enabled (page 208) is set to yes in the package configuration file,
Serviceguard will reboot the node if there is a failure of that specific service.
• If node_fail_fast_enabled (page 198) is set to yes in the package configuration file,
and the package fails, Serviceguard will halt (reboot) the node on which the package
is running.
For more information, see “Package Configuration Planning ” (page 118) and Chapter 6
(page 189).
90 Understanding Serviceguard Software Components