About calibration

About calibration in a DB2 for LUW environment

What happens during the Spotlight calibration process

The dataflow components that display on the DB2 for LUW (Linux, Unix, and Windows) database, database partition, or instance home page on your Spotlight desktop show the rate of different types of dataflows in your system over time. The speed of a home page dataflow varies based on the volume of data being transferred within the database or the instance. The greater the data traffic, the faster the flow.

Each home page dataflow corresponds to a type of dataflow in your database, partition, or instance. In order that home page dataflows represent actual dataflows in your system accurately, Spotlight must know the normal range of activity for this system. For example, if the normal range of a specific type of data flow in your database during a specific span of time is from 0 to 100, a value of 8 is slow¾the corresponding home page dataflow moves slowly. However, if the range is from 0 to 10, a value of 8 is very fast¾the home page dataflow moves much faster.

Spotlight provides a calibration tool that calculates the normal range of dataflows in your connection¾that is, in the database or database partition to which you are connected and in the instance to which this database or partition belongs. When you start the calibration process, Spotlight measures the flow of data through your system over a set period of time. It then uses this data to set the upper limit of each dataflow on the database or database partition home page and on the corresponding instance home page. (Spotlight always uses zero as the lowest value when calculating the normal range of values for your system.)

The calibration window

The first time you open a connection you created in Spotlight, the calibration window is displayed, prompting you to enter a length of time for the calibration. After you provide the information and close the window, the calibration process begins.

Connections to multiple-partition databases

You can set up a connection to a multiple-partition DB2 for LUW database is several ways. The way the connection is configured determines how the calibration process is run:

• If the connection is set up with Global selected in the DB2 Node field, the calibration process simultaneously calibrates all of the selected database’s associated partitions (nodes) for the same length of time.  
• If the connection is set up with the DB2 Auto Monitor Nodes option selected, the Connection Manager creates a separate connection automatically for each partition for the database. (However, you connect to and disconnect from these partitions simultaneously through the single database connection set up in the connection profile.) When you open this connection for the first time, Spotlight displays a succession of calibration windows, one for each of the partitions, prompting you for the length of time for the calibration. Calibration begins on each partition when you close its calibration window.
• If your connection is set up with a specific partition selected in the DB2 Node field, the calibration is run on that database partition only.  

During the course of a calibration the user may still cancel, change, or stop the calibration process. The action (cancel, change, stop) affects the database and its associated partitions in the following ways:  

• If your connection is set up with the Global option selected in the DB2 Node field, the action is performed at the database level across all partitions simultaneously.
• If the connection is set up at with the DB2 Auto Monitor Nodes option selected, the action is performed at the database level and across all partition connections simultaneously.
• If your connection is set up for the specific database partition specified in the DB2 Node field, the action is performed on that database partition only.

When to run calibration

Spotlight automatically runs calibration when you open a open a connection for the first time in Spotlight database for the first time. However, you can choose to run the calibration at any time.

If the data traffic in your database or database partition has increased or decreased significantly since you last ran a calibration, calibrate that system again so that your home page dataflows accurately depict your system’s activity.

Saving the calibration values

When you disconnect from the database or database partition connection, you are prompted to save any connection changes. This save includes the calibration values for the connection home pages. The calibration values for the connection are used until you change them or until you perform another calibration.

Related topics

Calibrating Spotlight connections

Setting up a connection profile for a DB2 for LUW database or partition