From the Pound man page:
HIGH-AVAILABILITY
Pound attempts to keep track of active back-end servers, and will tem-
porarily disable servers that do not respond (though not necessarily
dead: an overloaded server that Pound cannot establish a connection to
will be considered dead). However, every alive_check seconds, an
attempt is made to connect to the dead servers in case they have become
active again. If this attempt succeeds, connections will be innitiated
to them again.
In general it is a good idea to set this time interval as low as is
consistent with your resources in order to benefit from resurected
servers at the earliest possible time. The default value of 30 seconds
is probably a good choice.
Set the interval to 0 to disable this feature. The clients that happen
upon a dead backend server will just receive a 503 Service Unavailable
message.
The ha_port parameter specifies an additional port that is used only
for viability checks: if this port is specified in a BackEnd directive,
Pound will attempt periodically (every Alive seconds) to connect to
this port. If the port does not respond the server is considered dead.
/Bart
