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98
C
4: S
HAPTER
ERVER
How the Failover
System Works
F
C
AILOVER
ONFIGURATION
if it is trying to re-establish a connection to the Active Server, it will
■
short-out the failover retry and timeout mechanism, make itself the
Active Server and let the client connect.
if it still has a connection to the Active Server, it refuses to let the client
■
connect.
The server-to-server connection mechanism is a continuous connection
and, due to its continuous nature, the Dormant server knows the
connection is lost as soon as it happens. When the connection is lost, the
Dormant server tries to re-establish a connection using the same
mechanism used during server startup, as described in
and Timeout for EMS
However, if the Dormant server receives a client connection request
while retrying its connection, the Dormant server assumes that the
Active server has definitely failed and failover occurs immediately. See
"Server Failover Mechanism"
to Active server.
Server Failover Mechanism
Once the Dormant server realizes that the Active server is no longer
available, it logs this message to its command window (and the audit
log):
**** Server Failover: failover occurred at
<date/time> ****
The server stops trying to open a connection to what was the Active
server, and assumes the Active server role itself.
defines how the various EMS services behave.
Behaviors"
If trap forwarding has been set up, the server will send a Major
severity trap stating that server failover has occurred by reporting:
Server Failover: failover occurred
event is implied based on when the trap is received.
Startup".
for details on the transition from Dormant
. The date and time of the
"Setting the Retry
"Active Server
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