4.1.2 HA Monitor's control of server termination
HA Monitor terminates a server in the event of a failure or when the operator executes a command. The conditions under which HA Monitor terminates a server depend on the server's mode (server mode or monitor mode).
- Organization of this subsection
(1) Server in the server mode
The principal circumstances under which HA Monitor terminates a server are as follows:
- The operator has executed a command:
-
If the operator has terminated the active server normally or has performed planned or forced shutdown of the server by entering a command provided by the program, HA Monitor terminates the standby server in the standby system that corresponds to the active server.
When the operator has executed a forced termination command provided by the program on the active server, HA Monitor performs the same processing as for planned termination. When the operator has executed a forced termination command provided by the program on the standby server, HA Monitor performs the same processing as for abnormal termination.
When the operator has executed the server hot-standby switchover command (monswap command), HA Monitor terminates the active server before performing hot-standby switchover.
When the operator has executed the standby server termination command (monsbystp command), HA Monitor terminates the specified standby server.
- A failure has occurred:
-
If HA Monitor detects a server failure, it performs one of the following operations, depending on settings specified in the server environment definition:
-
If execution of the hot standby operation is specified, HA Monitor terminates the active server before performing the hot standby operation.
-
If a restart of the active server is specified, HA Monitor changes the active server's status to active server restart wait state and then waits for the active server to be restarted.
-
The following table describes the events that result in server termination and the HA Monitor processing that occurs after the server has been terminated.
|
Event |
Server terminated by HA Monitor |
HA Monitor processing after termination |
|
|---|---|---|---|
|
Event on the server |
Normal termination of active server#1 |
Standby server |
-- |
|
Abnormal termination of active server#2 |
-- |
Automatic hot standby#3 |
|
|
Normal termination of standby server |
-- |
-- |
|
|
Abnormal termination of standby server#4 |
-- |
-- |
|
|
Event on HA Monitor |
Detection of an active server failure |
Active server#3 |
Automatic hot standby#3 |
|
Standby server termination command (monsbystp command) |
Standby server |
-- |
|
|
Server hot-standby switchover command (monswap command)#5 |
Active server |
Planned hot standby |
|
Legend: --: HA Monitor does nothing.
#1: Includes planned and forced server termination.
#2: Occurs when the server itself has detected a failure.
#3: If there is no standby server to which hot standby switching is to be performed, HA Monitor does nothing. If restart or manual is specified in the switchtype operand in the server environment definition, HA Monitor places the active server on restart wait state without terminating it. HA Monitor waits for the active server to be restarted without performing the hot standby operation.
#4: Occurs when a forced server termination has occurred or the server itself has detected a failure.
#5: If there is no standby server to which hot standby switching is to be performed, HA Monitor does nothing.
(2) Server in the monitor mode
The user uses HA Monitor commands to switch over and terminate a server in the monitor mode.
The following table describes the events that result in server termination and the HA Monitor processing that occurs after the server has terminated.
|
Event |
Server terminated by HA Monitor |
HA Monitor processing after termination |
|
|---|---|---|---|
|
Event on the server |
Normal termination of active server |
-- |
-- |
|
Abnormal termination of active server |
-- |
Planned or automatic hot standby#1, #2 |
|
|
Normal termination of standby server |
-- |
-- |
|
|
Abnormal termination of standby server |
-- |
-- |
|
|
Event on HA Monitor |
Monitor-mode server termination command (monend command) |
Active server#1 and standby server |
-- |
|
Standby server termination command (monsbystp command) |
Standby server |
-- |
|
|
Server hot-standby switchover command (monswap command) |
Active server#3 |
Planned hot standby#3 |
|
Legend: --: HA Monitor does nothing.
#1: If a server termination command is specified in the termcommand operand in the server environment definition, HA Monitor executes the server termination command and terminates the active server specified in the server termination command.
#2: The operator requests the processing by executing the server hot-standby switchover command (monswap command) from the active system. If a server monitoring command is specified for the ptrlcmd_ex or patrolcommand operand in the server environment definition, HA Monitor performs restart or automatic hot-standby switchover. If there is no standby server to which hot standby switching is to be performed, HA Monitor does nothing.
#3: The operator performs planned termination of the active server, and then executes the server hot-standby switchover command (monswap command) from the active system. If a server termination command is specified in the termcommand operand in the server environment definition, the monswap command can be used to terminate the active server. If there is no standby server to which hot standby switching is to be performed, HA Monitor does nothing.