Using SNAplus2 in a High Availability Environment
Using SNAplus2 with MC/ServiceGuard
and become active. If this parameter is not specified, 10 retries will be allowed. Any number between 0 and 600 (inclusive) can be specified.
The return code of snapmon is 0 if the LS was active at some time while snapmon was running. Otherwise, a
One snapmon Service Command will be listed in the Package Control Script for each SNAplus2 LS that should be monitored. For example, to monitor an SNAplus2 LS called HALS, you might put the following line in the Package Control Script:
SERVICE_CMD[0]=”/opt/sna/bin/snapmon
When ServiceGuard starts the SNAplus2 package, it will also start the snapmon Service to monitor the package. The snapmon utility will obtain the status of the HALS connection from SNAplus2 every second. Snapmon will wait 60 seconds for th e LS to become active. If HALS fails to become active within 60 seconds, or if it activates and then deactivates, the snapmon process will terminate. The termination of the process will signal ServiceGuard that the SNAplus2 package is no longer providing SNA network connectivity, and the package should be migrated to another server.
Once you have created the basic package, read this section to determine how to customize your SNAplus2 package. You will need to modify the SNAplus2 Package Control Script to complete your SNAplus2 package definition.
Specifying a Package IP Address
An IP Address must be associated with the SNAplus2 package even if you are not using a LAN (802.3, Token Ring, or FDDI) for SNA network connectivity. This is a ServiceGuard requirement. This address is called a “floating” IP address, because whenever ServiceGuard migrates a package (or performs a local failover), the floating IP address moves with the package. Since ServiceGuard moves the floating IP address with the package, a ssociating an IP address with a package provide s a high degree of availability when access to a particular LAN adapter has been cut off .
ServiceGuard prevents TCP/IP connections from being disconnected when a local LAN failover occurs. Although an IP address must be associated with the SNAplus2 package, there are only limited uses for this address in SNAplus2 networks. Users of SNAplus2 applications will no t always be able to take advantage of ServiceGuard’s local failover
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