2.2.4 Flow of processing for monitoring a server

This subsection provides an overview of the processing performed by HA Monitor and HA Monitor Kit when monitoring a server (Oracle instance or Oracle listener). Note that the figures used in this subsection show examples in which an Oracle instance or an Oracle listener is associated with a single server.

Organization of this subsection
(1) Flow of processing for monitoring an Oracle instance
(2) Flow of processing for monitoring an Oracle listener

(1) Flow of processing for monitoring an Oracle instance

The following figure provides an overview of the processing performed by HA Monitor and HA Monitor Kit when an Oracle instance is monitored.

Figure 2-11 Overview of processing for monitoring an Oracle instance

[Figure]

[Figure]

#1: HA Monitor executes the server monitoring command.

#2: The processing in this part is repeated at the monitoring interval specified in the PATROL_INTERVAL environment variable of the server monitoring command.

#3: HA Monitor Kit issues SQL queries (database accesses and I/O checks). If there is no response within the specified length of time, a slowdown is considered to have occurred. You specify the time to wait before declaring a slowdown using PATROL in the Oracle instance control definition file.

#4: HA Monitor Kit checks whether the following Oracle instance processes exist:

CKPT, DBW0, LGWR, PMON, SMON

#5: When a single server is used to control multiple Oracle instances, the flow of processing described in this subsection is repeated as many times as there are Oracle instances.

(2) Flow of processing for monitoring an Oracle listener

The following figure provides an overview of the processing performed by HA Monitor and HA Monitor Kit when an Oracle listener is monitored.

Figure 2-12 Overview of processing for monitoring an Oracle listener

[Figure]

[Figure]

#1: HA Monitor executes the server monitoring command.

#2: The processing in this part is repeated at the monitoring interval specified in the PATROL_INTERVAL environment variable of the server monitoring command.

#3: HA Monitor Kit executes the listener control utility command and issues a query. You specify the time to wait before declaring a slowdown using PATROL in the Oracle listener control definition file.

#4: HA Monitor Kit checks whether the Oracle listener's TNSLSNR process exists.

#5: When a single server is used to control multiple Oracle instances, the flow of processing described in this subsection is repeated as many times as there are Oracle instances.