Virtual-Disk-Guide/docbook/Performance.xml at master · timlnx/Virtual-Disk-Guide · GitHub

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<chapter xmlns="http://docbook.org/ns/docbook"
         xmlns:xl="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         xml:id="VDG-Performance" version="5.1">

  <title>Performance Considerations</title>

  <para>
    Managing disk images doesn't stop at file manipulation and storage
    pool monitoring. After you create a disk image something else is
    going to use it. That's where performance tuning considerations
    come into play. This section straddles the line between system
    administrator and application developer roles. What I mean to say
    is that application of some techniques in this section may require
    knowledge which is outside of your domain as a system
    administrator. To help bridge the knowledge gap I'll include notes
    on how to identify what you're looking for when tuning the system.
  </para>

  <para>
    Many performance tuning decisions come down to one question:
    <emphasis>In the event of catastrophic system failure, how
    expensive is it to replace the data?</emphasis> If that value is
    low you can reach higher levels of performance at the cost of
    higher risk of data loss. If that value is high you can reach
    greater levels of data integrity at the cost of performance.
  </para>

  <para>
    In this section we'll cover the following topics:
  </para>

  <itemizedlist>
    <listitem>
      <para>
        Selecting the right disk caching mode
      </para>
    </listitem>
    <listitem>
      <para>
        Selecting the right virtual device
      </para>
    </listitem>
    <listitem>
      <para>
        Selecting the right I/O scheduler
      </para>
    </listitem>
    <listitem>
      <para>
	Balancing resources with cgroups
      </para>
    </listitem>
  </itemizedlist>

  <para>
    You may also be interested in reading over <xref
    linkend="VDG-Formats" />.
  </para>

  <xi:include href="performance/caching.xml"/>
  <!-- <xi:include href="performance/device.xml"/> -->
  <xi:include href="performance/scheduler.xml"/>
  <!-- <xi:include href="performance/cgroups.xml"/> -->
</chapter>