openstack/openstack-manuals
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Merge "Added Thin/Thick description to VMDK driver section"

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Jenkins 2015-06-20 16:22:37 +00:00 committed by Gerrit Code Review
commit 5eb4cf310d
1 changed files with 27 additions and 11 deletions
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doc/config-reference/block-storage/drivers/vmware-vmdk-driver.xml
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@ -55,14 +55,31 @@
</section>
<section xml:id="vmdk_disk_type">
<title>VMDK disk type</title>
<para>The VMware VMDK drivers support the creation of VMDK
disk files of type <literal>thin</literal>,
<literal>lazyZeroedThick</literal>, or
<literal>eagerZeroedThick</literal>. Use the
<code>vmware:vmdk_type</code> extra spec key with the
appropriate value to specify the VMDK disk file type. The
following table captures the mapping between the extra
spec entry and the VMDK disk file type:</para>
<para>The VMware VMDK drivers support the creation of VMDK disk file
types <literal>thin</literal>, <literal>lazyZeroedThick</literal>
(sometimes called thick or flat), or <literal>eagerZeroedThick</literal>.
</para>
<para>
A thin virtual disk is allocated and zeroed on demand as the space
is used. Unused space on a Thin disk is available to other users.
</para>
<para>
A lazy zeroed thick virtual disk will have all space allocated at
disk creation. This reserves the entire disk space, so it is not
available to other users at any time.
</para>
<para>
An eager zeroed thick virtual disk is similar to a lazy zeroed thick
disk, in that the entire disk is allocated at creation. However, in
this type, any previous data will be wiped clean on the disk before
the write. This can mean that the disk will take longer to create,
but can also prevent issues with stale data on physical media.
</para>
<para>
Use the <literal>vmware:vmdk_type</literal> extra spec key with the
appropriate value to specify the VMDK disk file type. This table
shows the mapping between the extra spec entry and the VMDK disk
file type:</para>
<table rules="all">
<caption>Extra spec entry to VMDK disk file type
mapping</caption>
@ -91,9 +108,8 @@
</tr>
</tbody>
</table>
<para>If you do not specify a <code>vmdk_type</code> extra
spec entry, the default disk file type is
<literal>thin</literal>.</para>
<para>If you do not specify a <code>vmdk_type</code> extra spec entry,
the disk file type will default to <literal>thin</literal>.</para>
<para>The following example shows how to create a
<code>lazyZeroedThick</code> VMDK volume by using the
appropriate <code>vmdk_type</code>:</para>