Informix Memory Grant Manager Test

The Memory Grant Manager (MGM) is a database server component that coordinates the use of memory, CPU virtual processors (VPs), disk I/O, and scan threads among decision-support queries. The MGM dynamically allocates the following resources for decision-support queries:

• The number of scan threads started for each decision-support query
• The number of threads that can be started for each query
• The amount of memory in the virtual portion of database server shared memory that the query can reserve

The MGM facilities are utilized to limit the memory resources granted to decision-support queries when the database server is deployed for heavy OLTP (online transaction processing) use. Besides, the MGM facilities let you to designate a larger proportion of the memory resources to parallel processing during off-peak hours, which achieves higher throughput for decision-support queries and improves server performance. If the memory resource allocation is not done properly, query execution may get delayed due to the insufficient memory resources, the users may experience delayed response to their queries and also the performance of the database server degrades. To avoid such unpleasant situation, you should continuously monitor the MGM memory utilization to accurately find out whether the memory issues are responsible for slow down in the query execution. This can be achieved using the Informix Memory Grant Manager test.

When the database server has heavy OLTP (online transaction processing) use, and you find performance is degrading, you can use the MGM facilities to limit the memory resources granted to decision-support queries. During off-peak hours, you can designate a larger proportion of the memory resources to parallel processing, which achieves higher throughput for decision-support queries. When query execution is delayed due to the insufficient memory resources, the users may experience delayed response to their queries and also the performance of the database server degrades. To avoid such unpleasant situation, you should continuously monitor the MGM memory utilization to accurately find out whether the memory issues are responsible for slow down in the query execution. This can be achieved using the Informix Memory Grant Manager test.

This test accurately reveals the details on MGM memory utilization of the database server.

Target of the test : A 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.
User	A valid Informix user name.
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
Total memory	Indicates the total size of the MGM memory.	MB
Used memory	Indicates the amount of MGM memory that was utilized by the server.	MB	A high value of this measure indicates that the MGM memory is running out of space, you may need to allocate additional resources
Free memory	Indicates the amount of MGM memory that is currently available for use.	MB	The value of this measure should be high.
Memory usage	Indicates the percentage of MGM memory that was utilized by the server.	Percent