MySQL Instance Manager has been deprecated and is removed in MySQL 5.5.
To monitor the status of each guarded server instance, the MySQL
Instance Manager attempts to connect to the instance at regular
intervals using the
MySQL_Instance_Manager@localhost user account
with a password of
You are not required to create this account for MySQL Server; in fact, it is expected that it will not exist. Instance Manager can tell that a server is operational if the server accepts the connection attempt but refuses access for the account by returning a login error. However, these failed connection attempts are logged by the server to its general query log (see Section 5.4.3, “The General Query Log”).
Instance Manager also attempts a connection to nonguarded server
instances when you use the
SHOW INSTANCES or
SHOW INSTANCE STATUS command. This is the
only status monitoring done for nonguarded instances.
Instance Manager knows if a server instance fails at startup because it receives a status from the attempt. For an instance that starts but later crashes, Instance Manager receives a signal because it is the parent process of the instance.
Beginning with MySQL 5.1.12, Instance Manager tracks instance states so that it can determine which commands are permitted for each instance. For example, commands that modify an instance's configuration are permitted only while the instance is offline.
Each instance is in one of the states described in the following
table. Guarded instances can be in any of the states. Nonguarded
instances can only be offline or online. Instance state
information is displayed in the
SHOW INSTANCES and
INSTANCE STATUS commands.
|The instance has not been started and is not running.|
|The instance is starting (initializing). Nonguarded instances cannot be in this state. A nonguarded instance goes directly from offline to online.|
|The instance is stopping. Nonguarded instances cannot be in this state. A nonguarded instance goes directly from online to offline, or stays offline if startup fails.|
|The instance has started and is running.|
|The instance was online but it crashed and is being restarted by Instance Manager, or else the instance failed to start at all and Instance Manager is again attempting to start it. Nonguarded instances cannot be in this state.|
|Instance Manager failed to start the instance after several attempts. (Instance Manager will try again later.) Nonguarded instances cannot be in this state.|
|Instance Manager was not able to start the instance, has given up, and
will make no further attempts until instructed
otherwise. To tell Instance Manager to try again, you
must first use |