AIX

There are many AIX operating system settings to consider that are not within the scope of this redbook. Some of the settings you can adjust are:

Adapter transmit and receive queue

TCP/IP socket buffer

IP protocol mbuf pool performance

Update file descriptors

Update the scheduler

However, two important settings are outlined in the next sections.

 

AIX with DB2

Separating your DB2 log files from the physical database files can boost performance. You can also separate the logging and the database files from the drive containing the Journaled File System (JFS) service. AIX uses specific volume groups and file systems for the JFS logging.

The AIX filemon utility is used to view all file system input and output, and to strategically select the file system for the DB2 logs. The default location for the files is /home/<db2_instance>/<db2_instance>/NODExx/SQLyy/SQLOGDIR/.

To change the location of the files, at a DB2 command prompt, issue the following command:

db2 update db cfg for [database_name] using newlogpath 
[fully_qualified_path] 

It is recommended that you move the logs to a separate disk when your application shows more than a 20% I/O wait time.

 

AIX file descriptors (ulimit)

Specifies the number of open files permitted.

When should you try adjusting this value? The default setting is typically sufficient for most applications. If the value set for this parameter is too low, a Memory allocation error is displayed.

Check the UNIX reference pages on ulimit for the syntax for different shells. For the KornShell shell (ksh), to set ulimit to 2000, issue the following command:

ulimit -n 2000

Use smit (or smitty) to permanently set this value for a user.

Use the command ulimit -a to display the current values for all limitations on system resources. The default setting is 2000, which is also the recommended value.

  Prev | Home | Next

 

WebSphere is a trademark of the IBM Corporation in the United States, other countries, or both.

 

IBM is a trademark of the IBM Corporation in the United States, other countries, or both.

 

AIX is a trademark of the IBM Corporation in the United States, other countries, or both.