Informix Buffers Test

This test reports statistics pertaining to the caching and buffer flushing activities of the Informix database server.

Target of the test : An Informix Dynamic server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for the Informix server being monitored.

Configurable parameters for the test
Parameters Description

Test Period

This indicates how often should the test be executed.

Host

The IP address of the Informix Dynamic server.

Port

The port number at which the specified host listens to.

Instance

The Informix server instance being monitored.

DB

Specify the name of a database on the server.

User

A valid Informix user name to login to the specified database.

Password

The password corresponding to the above user.

Confirm Password

Confirm the Password by retyping it here.

DBLocale

Specify the language/locale in which your database is installed. This will allow you to return the query in the language supported by your database. By default this attribute is set to “none”, which means that by default, queries are returned in the English locale.

ClientLocale

Specify the language/locale in which the eG agent is running. Normally, when you use an internal agent to monitor Informix, the ClientLocale and DBLocale will be same. However, the ClientLocale may differ when you are monitoring the Informix tests using a remote agent (agentless monitoring). By default, the ClientLocale is set to “none”, indicating that the eG agent runs in the English locale, by default.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Read cache hit ratio

The ratio of number of buffer reads to disk reads.

Percent

This measure is an indicator of the overall performance of your database server. This value should always be high.

Write cache hit ratio

The ratio of number of buffer writes to disk writes.

Percent

This measure is an indicator of the overall performance of your database server. This value should always be high.

Flushes

The rate at which buffer-pool buffers were flushed to disk.

Flushes/Sec

 

Foreground writes

The number of foreground writes per second during the last measurement period

Writes/Sec

Foreground writes should be avoided. They slow down the performance of your database server. If you find that foreground writes are occurring on a regular basis, tune the value of the page-cleaning parameters. Either increase the number of page cleaners or decrease the value of LRU_MAX_DIRTY.

LRU writes

The number of LRU writes per second during the last measurement period

Writes/Sec

Compare this value with Foreground_writes and Chunk_writes to get an understanding of how the buffer flushing occurs in Informix.

Chunk writes

The number of chunk writes per second during the last measurement period

Writes/Sec

Chunk writes are commonly performed by page-cleaner threads during a checkpoint or, possibly, when every page in the shared-memory buffer pool

is modified. Chunk writes, which are performed as sorted writes, are the most efficient writes available to the database server.

Compare this value with Foreground_writes and LRU writes to get an understanding of how the buffer flushing occurs in Informix.