Tuning AIX virtual memory

The AIX® virtual address space is managed by the Virtual Memory Manager (VMM). Monitor the paging statistics to identify problems with virtual memory usage.

To monitor paging statistics and identify potential issues, complete the following steps:

1. Run the vmstat command. Review the paging statistics in the pi and po columns. An occasional nonzero value is not a concern because paging is the main principle of virtual memory. If the values are constantly nonzero, there might be a memory bottleneck.
2. If paging occurs constantly, verify whether the problem is caused by heavy use of the file system cache. Review the output from the following command:

   vmstat -I 5

3. If the values for pi and po columns are high, and the values are similar to the values for fi and fo columns, consider using the rbrw mount option on all active JFS2 file systems to reduce or eliminate the paging problem.
4. If the paging problem persists after you use the rbrw mount option for JFS2 file systems, run the AIX vmo command to tune the virtual memory system. For more information about using the vmo command, see the documentation for the AIX operating system.