(dv) 4.0:Explanation of Memory Usage Statistic in AccountCenter

  • This page was last modified on March 21, 2011, at 15:30.
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Contents

Objective

Sometimes the memory usage statistic in the Server Status portion of the (mt) AccountCenter shows that more than 100% of the server's memory is being used. Offhand, that may seem unusual or even impossible. This article aims to clarify that it is actually fairly common on machines that host multiple VPS instances (virtual private servers). Here is an example of how the Server Status window may look:

Dvserverstatus.jpg

Background

The Server Status memory meter takes two things into account:

  • The resource parameter "oomguarpages", also known as "guaranteed" memory, or RAM.
  • The resource parameter "privvmpages", also known as "burstable" memory.


An individual (dv) 4.0 will often be able to use 100% of the "guaranteed" memory AND some "burstable" memory. The reason is that when other (dv) instances are not using all of their guaranteed memory, the unused resources are made available to other instances as part of a virtual "pool". If your AccountCenter shows that your (dv) is using more than 100% memory, that means that it is dipping into the pool of burstable memory.

Breakdown

  • Oomguarpages is the amount of memory "guaranteed" to your (dv) Dedicated-Virtual Server.
  • Privvmpages refers to "burstable" memory, which is not always available to your individual server.
  • 100% usage in Server Status means that all "guaranteed" memory is in use. This number may be greater than 100% if your (dv) is utilizing "burstable" or pool memory.
  • If your server is constantly at or above 100%, consider optimizing your applications and configuration to reduce memory usage. Or, you may upgrade your server to the next level through the AccountCenter. While it is okay for your server to use 100% or more from time to time, your sites/applications may suffer in cases where pool memory is not available to your server. It is best to have an average memory use of less than 100%.
  • This percentage shown in Server Status will often differ from the "Resources" page in the Plesk Power Panel, because that tool is reporting different usage information. The percentage reported in the Server Status is considered to be more accurate when trying to determine if an upgrade is necessary.

Example

  • (dv) Dedicated-Virtual Server 512 MB
  • If your server is using all 512 MB of memory, then Server Status will show 100%.
  • If Server Status shows 150% memory usage, then you are using ~768 MB memory.
  • The additional 256 MB of memory that the server is using is not guaranteed.
  • This (dv) Dedicated-Virtual Server should be tuned or upgraded if this usage becomes the norm.
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