4.5.3 Controlling the server start and termination (multi-standby)

(a) Determining the active server or standby server

When the multi-standby function is used, HA Monitor determines the start type based not only on the status of the active server in the remote host but also on the combination of active server status and standby server status. The following table describes how this determination in made when the multi-standby function is used.

Table 4‒10: Determining the active server or standby server (when using the multi-standby function)

Status of remote host		Server environment definition
		Defined as active server	Defined as a standby server#1
Active server exists.	Startup processing is underway.	Start as standby server.	Start as standby server.
	Execution processing is underway.	Start as standby server.	Start as standby server.
	Termination processing is underway.	Cannot be started.#2	Cannot be started.#2
	Hot standby operation is underway.	Wait until the active server starts.#3	Wait until the active server starts.#3
There is no active server.		Start as active server.	Wait until the active server starts.#3
Retrying startup#4		Start as active server.	Start as a standby server.
No server is found (or HA Monitor is inactive).		Start as active server.	Wait until the active server starts.#3
The server status cannot be checked.		Retry processing.#5	Wait until the active server starts.#3

#1: If the status is Retrying startup, the operation is the same as for Defined as active server.

#2: Cancels the server startup processing.

#3: Places startup of the standby server on hold until startup of the active server on the remote host is confirmed. After start of the active server startup processing is confirmed, HA Monitor starts the server as the standby server (active server start wait state).

#4: For details about the retrying startup status, see 3.2.7 Performing start retries during hot standby processing.

#5: If HA Monitor is unable to check the server status on the remote host due to a host failure or a monitoring path failure on the remote host, it retries for only one minute. If the status still cannot be checked after one minute of retries, HA Monitor determines that no server is available on the remote host due to a failure and places the server in the active server start wait state.

For details about the user operation when a server is placed in the active server start wait state, see 7.4.1 Starting a server in the wait state and then restarting jobs.

(b) Start type for restarting a server

When a server is restarted after a failure, an active server might already be running on the remote host. Therefore, HA Monitor does not start the server as an active server, even if it is defined as an active server, until the server status on the remote host can be verified. Once the server status on the remote host has been verified, determine whether the server is to be started as the active server or a standby server.

The following table describes how the start type is determined for restarting a server that has been defined as the active server when the multi-standby function is used.

Table 4‒11: Determining the start type for restarting a server (when using the multi-standby function)

Status of remote host		Server start type
Active server exists.	Startup processing is underway.	Start as standby server.
	Execution processing is underway.	Start as standby server.
	Termination processing is underway.	Cannot be started.#1
Hot standby switching from standby server to active server is underway.		Start as standby server.
No server is found (or HA Monitor is inactive).		Wait until the active server starts.#2
The server status cannot be checked.		Wait until the active server starts.#2

#1: Cancels the server startup processing.

#2: Places startup of the standby server on hold until startup of the active server on the remote host is confirmed (active server start wait state). After start of the active server startup processing is confirmed, HA Monitor starts the server as the standby server.

For details about the user operation when a server is placed in the active server start wait state, see 7.4.1 Starting a server in the wait state and then restarting jobs.