openstack/openstack-manuals
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Updated deprecated usage for libvirt options.

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Changed libvirt_image_* => image_*

Closes-bug: #1255324

Change-Id: I52022b7be38acb008c949b52dabd209d4f672f00
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Summer Long 2014-05-04 14:44:42 +10:00 committed by Andreas Jaeger
parent d87badc476
commit a07a2c037d
1 changed files with 29 additions and 21 deletions
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50
doc/config-reference/compute/section_compute-configure-backing-storage.xml
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@ -4,27 +4,35 @@
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0">
<title>Configure Compute backing storage</title>
<para>Backing Storage is the storage used to provide
the expanded operating system image, and any ephemeral storage.
Inside the virtual machine, this is normally presented as two
virtual hard disks (for example, /dev/vda and /dev/vdb respectively).
However, inside OpenStack, this can be derived from one of three
methods: LVM, QCOW or RAW, chosen using the
<literal>libvirt_images_type</literal> option in <filename>nova.conf</filename>
on the compute node.</para>
<para>QCOW is the default backing store. It uses a copy-on-write philosophy to
delay allocation of storage until it is actually needed. This means that the
space required for the backing of an image can be significantly less on the real
disk than what seems available in the virtual machine operating system.
<para>
Backing Storage is the storage used to provide the expanded
operating system image, and any ephemeral storage. Inside the
virtual machine, this is normally presented as two virtual hard
disks (for example, <filename>/dev/vda</filename> and
<filename>/dev/vdb</filename> respectively). However, inside
OpenStack, this can be derived from one of three methods: LVM,
QCOW or RAW, chosen using the <literal>images_type</literal>
option in <filename>nova.conf</filename> on the compute node.
</para>
<para>
QCOW is the default backing store. It uses a copy-on-write
philosophy to delay allocation of storage until it is actually
needed. This means that the space required for the backing of an
image can be significantly less on the real disk than what seems
available in the virtual machine operating system.
</para>
<para>RAW creates files without any sort of file formatting, effectively creating
files with the plain binary one would normally see on a real disk. This can
increase performance, but means that the entire size of the virtual disk is
reserved on the physical disk.
</para>
<para>Local <link xlink:href="http://http//en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux)">LVM volumes</link>
can also be used.
Set <literal>libvirt_images_volume_group=nova_local</literal> where <literal>nova_local</literal> is the name
of the LVM group you have created.
<para>
RAW creates files without any sort of file formatting, effectively
creating files with the plain binary one would normally see on a
real disk. This can increase performance, but means that the
entire size of the virtual disk is reserved on the physical disk.
</para>
<para>
Local <link
xlink:href="http://http//en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux)"
>LVM volumes</link> can also be used. Set
<literal>images_volume_group = nova_local</literal> where
<literal>nova_local</literal> is the name of the LVM group you
have created.
</para>
</section>