10.2.3 HADB server operation modes

The following operation modes are available for the HADB server:

Normal mode
Quiescence mode
Offline mode
Maintenance mode

The following table describes these operation modes in detail.

Table 10‒5: Details of the HADB server's operation modes
No.	Operation mode	Explanation
1	Normal mode	This is the normal operation mode. In the normal mode, the HADB server and HADB clients can execute SQL statements and commands as usual. If you execute the `adbstart` command with its option omitted when you start the HADB server for the first time, the HADB server starts in the normal mode.
2	Quiescence mode	This operation mode prevents database updating. For example, use this mode to back up a database while keeping the HADB server running. In the quiescence mode, the HADB server and HADB clients can execute SQL statements that search the database. However, SQL statements that update the database cannot be executed. Some commands cannot be executed either. For details about the SQL statements and commands that can be executed in the quiescence mode, see adbstart (Start the HADB Server) in the manual HADB Command Reference.
3	Offline mode	This operation mode rejects connection requests from HADB clients installed on server machines other than the server machine on which the HADB server is installed. Use this mode, for example, when you want to execute commands taking advantage of the maximum processing performance of the HADB server. In the offline mode, HADB clients installed on the same server machine as the HADB server can execute SQL statements and commands as usual. However, HADB clients installed on server machines other than the server machine on which the HADB server is installed cannot execute SQL statements and commands. For details about the SQL statements and commands that can be executed in the offline mode, see adbstart (Start the HADB Server) in the manual HADB Command Reference.
4	Maintenance mode	In this operation mode, the HADB server rejects connection requests from applications. You can execute only the specified commands (such as the `adbmodarea` command) in the maintenance mode. For details about the commands that can be executed in the maintenance mode, see SQL statements and commands that can be executed in each HADB server operation mode in adbstart (Start the HADB Server) in the manual HADB Command Reference. Use the maintenance mode in the following cases: When you execute a command that cannot be executed concurrently with other commands and applications. When you return a node to the multi-node configuration. For details about returning a node to the multi-node configuration, see 16.15.3 Returning a node to the multi-node configuration.

Organization of this subsection

(1) Changing the operation mode
(2) Checking the operation mode

(1) Changing the operation mode

You can change the HADB server's operation mode while you are starting the server or while it is running. The methods of changing the operation mode are as follows:

■ Changing the operation mode to the normal mode

To change the mode while starting the HADB server

Execute the adbstart --normal command when you start the HADB server.
To change the mode while the HADB server is running

Execute the adbchgsrvmode --normal command while the HADB server is running in the quiescence, offline, or maintenance mode.

■ Changing the operation mode to the quiescence mode

To change the mode while starting the HADB server

Execute the adbstart --quiescence command when you start the HADB server.
To change the mode while the HADB server is running

Execute the adbchgsrvmode --quiescence command while the HADB server is running in the normal mode. You can change the operation mode from the normal mode to the quiescence mode.

■ Changing the operation mode to the offline mode

To change the mode while starting the HADB server

Execute the adbstart --offline command when you start the HADB server.
To change the mode while the HADB server is running

Execute the adbchgsrvmode --offline command while the HADB server is running in the normal mode. You can change the operation mode from the normal mode to the offline mode.

▪ Changing the operation mode to the maintenance mode

To change the mode while starting the HADB server

Execute the adbstart --maintenance command when you start the HADB server.
To change the mode while the HADB server is running

Execute the adbchgsrvmode --maintenance command while the HADB server is running in the normal mode. You can change the operation mode from the normal mode to the maintenance mode.

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(2) Checking the operation mode

You can use the following command to check the HADB server's operation mode:

adbls -d srv

Executing this command displays the HADB server's status. Check the item STATUS in the execution result.

When STATUS is ACTIVE

The operation mode is the normal mode.
When STATUS is QUIESCE

The operation mode is the quiescence mode.
When STATUS is OFFLINE

The operation mode is the offline mode.
When STATUS is MAINTNCE

The operation mode is the maintenance mode.

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