4.4.2 Hot standby control on grouped servers
When servers are grouped, hot standby control depends on the combination of the server switchover types specified for the individual servers in the server group.
Note that a server switchover type cannot be specified for a server in the monitor mode. If a server group contains a server in the monitor mode, it is assumed that exchange is specified as its server switchover type. If you want to perform the hot standby operation in the event of a server failure or slowdown on a server in the monitor mode, you must create a server monitoring command.
The following table shows the relationship between the server switchover type and HA Monitor's hot standby control for each event that triggers the hot standby operation.
|
Event that triggers the hot standby operation |
Combination of server switchover types |
|||||
|---|---|---|---|---|---|---|
|
Event classification |
Server on which the event has occurred |
exchange only |
exchange and no_exchange |
no_exchange only |
||
|
Is there any server running in the group? |
Is there any server running in the group? |
|||||
|
Yes |
No |
Yes |
No |
|||
|
Server failure has occurred. |
Server for which exchange is specified. |
Performs grouped- system switchover. |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
-- |
-- |
|
Server for which no_exchange is specified. |
-- |
Waits for grouped- system switchover.#2 |
Performs the hot standby operation independently.#1 |
Waits for grouped- system switchover.#2, #3 |
Performs the hot standby operation independently.#1 |
|
|
Server slowdown has occurred. |
Server for which exchange is specified. |
Performs grouped- system switchover. |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
-- |
-- |
|
Server for which no_exchange is specified. |
-- |
Depends on another setting.#4 |
Performs the hot standby operation independently.#1 |
Depends on another setting.#4 |
Performs the hot standby operation independently.#1 |
|
|
Host failure has occurred. |
Server for which exchange is specified. |
Performs grouped- system switchover. |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
-- |
-- |
|
Server for which no_exchange is specified. |
-- |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
|
|
Planned hot standby is to be performed. |
Server for which exchange is specified. |
Performs grouped- system switchover. |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
-- |
-- |
|
Server for which no_exchange is specified. |
-- |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
Performs grouped- system switchover. |
Performs the hot standby operation independently.#1 |
|
- Legend:
-
--: Invalid combination
- #1:
-
If the standby system contains a standby server that belongs to the same server group and that is on grouped-system switchover wait state, HA Monitor starts that standby server as the active server at the same time.
- #2:
-
The standby server has started in the standby system and is waiting for grouped-system switchover on the server group. For details about the grouped-system switchover wait state, see 7.4.1 Starting a server in the wait state and then restarting jobs.
- #3:
-
HA Monitor performs grouped-system switchover if a failure occurs on all servers.
- #4:
-
If cancel is specified, HA Monitor terminates the server abnormally. The standby server is placed on grouped-system switchover wait state. If no_cancel is specified, HA Monitor continues monitoring server status. The standby server is not placed on grouped-system switchover wait state.