FAQ / Can RSF-1 be configured to fail over services if network connectivity is lost.

RSF-1 is configurable to monitor the state of network connections and perform a fail over of any services bound to that interface.

Enable IP failure detection in RSF-1 by adding the following line (IPDEVICE_MONITOR) at
the top of the RSF-1 configuration file (/opt/HAC/RSF-1/etc/config) in
the global section:

###############################################################################
############## Optional global defaults & definitions come first. #############
###############################################################################

CLUSTER_NAME Network_Failover_Example
IPDEVICE_MONITOR 5,10
POLL_TIME 2
REALTIME 1

###############################################################################
############## End of global section, start of machines section. ##############
###############################################################################

The first parameters to IPDEVICE_MONITOR (5 in the above example) dictates the number of checks that have to fail consecutively before the interface is marked down, and the second (10 in the above example) is the number of consecutive positive checks before the interface is considered usable (again).

RSF-1 automatically works out which network device to monitor based on the services bound to an interface so no further configuration is required. Checking is done on all nodes in the cluster, so even if a node is not running any services, RSF-1 will continue to monitor the unused interfaces, and, should one go offline, prevent fail over to this node for services bound to that interface (as there is little point in failing over to a machine with an unusable interface for a service). Should the interface subsequently recover then RSF-1 will re-enable fail over for that interface.

If a network device has no associated service, then no monitoring is performed on that device. So for instance failure of a network device used purely for heart beating with no associated service will not cause a fail over.

Enabling strict checking

The example above checks for network interface availability (i.e. a physical link exists), but does not check to see if the interface is actually configured with an IP address; an interface with an address of 0.0.0.0 will pass the above test. To force RSF-1 to consider an interface down if it has no IP address use the option IFUP. ThisĀ  should be included in the IPDEVICE_MONITOR line between the keyword itself and the timeout values thus:

###############################################################################
############## Optional global defaults & definitions come first. #############
###############################################################################

CLUSTER_NAME Network_Failover_Example
IPDEVICE_MONITOR IFUP 5,10
POLL_TIME 2
REALTIME 1

###############################################################################
############## End of global section, start of machines section. ##############
###############################################################################

Posted in: Networking