My Oracle Support Banner

Aggressive swapping and low resources during RMAN backup on Linux X86 (Doc ID 360402.1)

Last updated on NOVEMBER 30, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 8.1.7.4 to 10.2.0.3 [Release 8.1.7 to 10.2]
Linux x86
Linux x86

Symptoms

A FULL RMAN backup gradually causes all of the OS FREE MEMORY to be used and SWAP SPACE to be used.

Changes

/proc/sys/vm/buffermem:

This controls the amount of the total system memory (as a percent) that will be used for buffer memory. It holds three values that can be set by writing a space-separated list to the file
1. Minimum percentage of memory that should be used for buffers
2. The system will try and maintain this amount of buffer memory when system memory is being pruned in the event of a low amount of system memory remaining
3. Maximum percentage of memory that should be used for buffers. Default setting: 2 10 60

/proc/sys/vm/pagecache:

This does the same job as /proc/sys/vm/buffermem, but it does it for memory mapping and generic caching of files.

/proc/sys/vm/freepages:

This controls how the system reacts to different levels of free memory. It holds three values that can be set by writing a space-separated list to the file:

  1. If the number of free pages in the system reaches this minimum limit, only the kernel will be permitted to allocate any more memory.

  2. If the number of free pages in the system falls below this limit, the kernel will start swapping more aggressively to free memory and maintain system performance.

  3. The kernel will try to keep this amount of system memory free. Falling below this value will start the kernel swapping. Default setting: 512 768 1024

Cause

To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!


In this Document
Symptoms
Changes
Cause
Solution

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.