a6bce01980
The XML root element of Docbook XML files should match the following format: <ELEMENT xmlns="http://docbook.org/ns/docbook" xmlns:xi="http://www.w3.org/2001/XInclude" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="THE_XML_ID_OF_THE_ELEMENT"> Change-Id: I02a75b63d0fb3ea4a7d015794b9229a94ddad279
73 lines
3.7 KiB
XML
73 lines
3.7 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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version="5.0"
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xml:id="qemu">
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<?dbhtml stop-chunking?>
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<title>QEMU</title>
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<para>From the perspective of the Compute service, the QEMU hypervisor is very similar to the KVM
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hypervisor. Both are controlled through libvirt, both support the same feature set, and all
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virtual machine images that are compatible with KVM are also compatible with QEMU. The main
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difference is that QEMU does not support native virtualization. Consequently, QEMU has worse
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performance than KVM and is a poor choice for a production deployment.</para>
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<para>The typical uses cases for QEMU are<itemizedlist>
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<listitem>
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<para>Running on older hardware that lacks
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virtualization support.</para>
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</listitem>
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<listitem>
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<para>Running the Compute service inside of a virtual
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machine for development or testing purposes, where
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the hypervisor does not support native
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virtualization for guests.</para>
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</listitem>
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</itemizedlist></para>
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<para>To enable QEMU, add these settings to
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<filename>nova.conf</filename>:<programlisting language="ini">compute_driver = libvirt.LibvirtDriver
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[libvirt]
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virt_type = qemu</programlisting></para>
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<para>
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For some operations you may also have to install the <command>guestmount</command> utility:</para>
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<para>On Ubuntu:
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<screen><prompt>#</prompt> <userinput>apt-get install guestmount</userinput></screen>
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</para>
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<para>On Red Hat Enterprise Linux, Fedora, or CentOS:
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<screen><prompt>#</prompt> <userinput>yum install libguestfs-tools</userinput></screen>
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</para>
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<para>On openSUSE:
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<screen><prompt>#</prompt> <userinput>zypper install guestfs-tools</userinput></screen>
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</para>
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<para>The QEMU hypervisor supports the following virtual machine image formats:</para>
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<itemizedlist>
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<listitem>
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<para>Raw</para>
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</listitem>
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<listitem>
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<para>QEMU Copy-on-write (qcow2)</para>
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</listitem>
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<listitem>
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<para>VMware virtual machine disk format (vmdk)</para>
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</listitem>
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</itemizedlist>
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<section xml:id="fixes-rhel-qemu">
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<title>Tips and fixes for QEMU on RHEL</title>
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<para>If you are testing OpenStack in a virtual machine, you must configure Compute to use qemu
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without KVM and hardware virtualization. The second command relaxes SELinux rules to
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allow this mode of operation (<link
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xlink:href="https://bugzilla.redhat.com/show_bug.cgi?id=753589">
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https://bugzilla.redhat.com/show_bug.cgi?id=753589</link>). The last two commands
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here work around a libvirt issue fixed in Red Hat Enterprise Linux 6.4. Nested
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virtualization will be the much slower TCG variety, and you should provide lots of
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memory to the top-level guest, because the OpenStack-created guests default to 2GM RAM
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with no overcommit.</para>
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<note><para>The second command, <command>setsebool</command>, may take a while.
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</para></note>
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<screen><prompt>#</prompt> <userinput>openstack-config --set /etc/nova/nova.conf libvirt virt_type qemu</userinput>
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<prompt>#</prompt> <userinput>setsebool -P virt_use_execmem on</userinput>
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<prompt>#</prompt> <userinput>ln -s /usr/libexec/qemu-kvm /usr/bin/qemu-system-x86_64</userinput>
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<prompt>#</prompt> <userinput>service libvirtd restart</userinput></screen>
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</section>
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</section>
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