Article ID: 111234, created on May 4, 2011, last review on Jun 11, 2014

  • Applies to:
  • Virtuozzo containers for Linux 4.6
  • Virtuozzo containers for Linux 4.0
  • Virtuozzo for Linux 3.x
  • Virtuozzo hypervisor 4.0
  • Virtuozzo hypervisor 4.0 for Mac Bare Metal
  • Virtuozzo hypervisor 5.0


If the server has a large amount of RAM available and disk operations are slow, it is possible to increase server performance by maximizing RAM usage instead of using SWAP.

Parallels Containers and Parallels Server Bare Metal intensively use SWAP, especially when the total RAM allocated for containers and virtual machines exceeds the amount of physical RAM available.

In such cases, disabling swap usage may lead to a performance degradation instead of a boost.

Decreasing SWAP usage will boost server performance only in cases when physical RAM is greater than the total amount of RAM allocated for containers and virtual machines.


Decrease the vm.swappiness and vm.vfs_cache_pressure kernel parameters:
~# sysctl -w vm.swappiness=20
~# sysctl -w vm.vfs_cache_pressure=100
These values are approximate, so you may change them according to your needs. To make these parameters permanent, add the corresponding lines to /etc/sysctl.conf:
~# grep vm /etc/sysctl.conf
vm.swappiness = 20
vm.vfs_cache_pressure = 100

Additional Information

For more information about virtual memory parameters, refer to Linux Kernel documentation:
VFS Shrinkage Tuning

Documentation for /proc/sys/vm/*

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