RESIDENT configuration parameter

Use the RESIDENT configuration parameter to specify whether resident and virtual segments of shared memory remain resident in operating-system physical memory.

onconfig.std value
RESIDENT 0
values
-1 - 99

0 = off

1 = lock the resident segment only

-1 = lock all resident and virtual segments

n = lock the resident segment and the next n -1 virtual segments. For example, if you specify 99 as the value, the resident segment is locked and the next 98 virtual segments are locked.

Certain platforms have different values. For information, see your machine notes.

takes effect
After you edit your onconfig file and restart the database server.
When you reset the value dynamically in your onconfig file by running the onmode -wf command.
When you reset the value in memory by running the onmode -wm command.

Usage

Some systems allow you to specify that the resident portion of shared memory must stay (be resident) in memory at all times. If your operating system supports forced residency, you can specify that resident and virtual segments of shared memory not be swapped to disk.
Warning: Before you decide to enforce residency, verify that the amount of physical memory available is sufficient to execute all required operating-system and application processes. If insufficient memory is available, a system hang could result that requires a reboot.

On AIX®, Solaris, or Linux™ systems that support large pages of memory, the DBSA can use operating system commands to configure a pool of large pages.

HCL Informix® can store non-message virtual memory segments on these large pages if you take the following steps:
  • Enable large page sizes by setting the IFX_LARGE_PAGES environment variable.
  • For virtual memory segments that you intend to store on large pages, set the RESIDENT parameter to lock those segments in physical memory, so that they cannot be swapped to disk

Storing virtual memory segments on large pages can offer significant performance benefits in large memory configurations.