Sun Cluster HA for Netscape Mail or Message Server Fault Probes

The Sun Cluster HA for Netscape Mail or Message Server fault probe checks the health of the mail or message server by probing it on all three service ports served by the server, namely the SMTP, IMAP, and POP3 ports:

• SMTP (port 25)--Executes an SMTP "hello" message on the server and then executes a quit command.

• IMAP (port 143)--Executes an IMAP4 CAPABILITY command followed by an IMAP4 LOGOUT command.

• POP3 (port 110)--Executes a quit command.

For all of these tests, the fault probe expects a response string from the server within the probe timeout interval. Note that a probe failure on any of the above three service ports is considered a failure of the server. To avoid spurious failovers, the nsmail fault probe uses a sliding window algorithm for tracking probe failures and successes. If the number for probe failures in the sliding window is greater than a pre-configured number, a takeover is initiated by the remote probe.