c641abaa62
This patch adds block storage troubleshooting documentation, which superseeds the old documentation. It's actually https://review.openstack.org/#/c/49972 - but that patch became a rebase hell, hence the new one. Change-Id: I37621e1bede368b57a5af5e33b2d131c7e28d488
129 lines
6.3 KiB
XML
129 lines
6.3 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<chapter 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" version="5.0"
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xml:id="managing-volumes">
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<?dbhtml stop-chunking?>
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<title>Block Storage</title>
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<para>The OpenStack Block Storage service works though the
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interaction of a series of daemon processes named cinder-*
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that reside persistently on the host machine or machines. The
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binaries can all be run from a single node, or spread across
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multiple nodes. They can also be run on the same node as other
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OpenStack services.</para>
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<section xml:id="section_block-storage-intro">
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<title>Introduction to Block Storage</title>
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<para>To administer the OpenStack Block Storage service, it is
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helpful to understand a number of concepts. You must make
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certain choices when you configure the Block Storage service
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in OpenStack. The bulk of the options come down to two
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choices, single node or multi-node install. You can read a
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longer discussion about storage decisions in <link
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xlink:href="http://docs.openstack.org/trunk/openstack-ops/content/storage_decision.html"
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>Storage Decisions</link> in the <citetitle>OpenStack
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Operations Guide</citetitle>.</para>
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<para>The OpenStack Block Storage service enables you to add extra
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block-level storage to your OpenStack Compute instances. This
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service is similar to the Amazon EC2 Elastic Block Storage
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(EBS) offering.</para>
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</section>
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<?hard-pagebreak?>
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<section xml:id="section_manage-volumes">
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<title>Manage volumes</title>
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<para>The default OpenStack Block Storage service implementation
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is an iSCSI solution that uses Logical Volume Manager (LVM)
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for Linux.</para>
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<note>
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<para>The OpenStack Block Storage service is not a shared
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storage solution like a Storage Area Network (SAN) of NFS volumes,
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where you can attach a
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volume to multiple servers. With the OpenStack Block
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Storage service, you can attach a volume to only one
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instance at a time.</para>
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<para>The OpenStack Block Storage service also provides
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drivers that enable you to use several vendors' back-end
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storage devices, in addition to or instead of the base LVM
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implementation.</para>
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</note>
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<para>The following high-level procedure shows you how to create
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and attach a volume to a server instance.</para>
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<procedure>
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<step><para>You must configure both OpenStack Compute and the
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OpenStack Block Storage service through the
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<filename>cinder.conf</filename> file.</para></step>
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<step>
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<para>Create a volume through the <command>cinder create</command> command. This command
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creates an LV into the volume group (VG) "cinder-volumes." </para>
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</step>
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<step>
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<para>Attach the volume to an instance through the
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<command>nova volume-attach</command> command.
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This command creates a unique iSCSI IQN that is
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exposed to the compute node.</para>
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<substeps>
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<step>
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<para>The compute node, which runs the instance, now has an active ISCSI session
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and new local storage (usually a /dev/sdX disk).</para>
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</step>
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<step>
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<para>libvirt uses that local storage as storage for the instance. The instance
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get a new disk, usually a /dev/vdX disk.</para>
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</step>
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</substeps>
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</step>
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</procedure>
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<para>For this particular walk through, there is one cloud
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controller running <systemitem class="service">nova-api</systemitem>,
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<systemitem class="service">nova-scheduler</systemitem>,
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<systemitem class="service">nova-objectstore</systemitem>,
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<literal>nova-network</literal> and
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<literal>cinder-*</literal> services. There are two
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additional compute nodes running
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<systemitem class="service">nova-compute</systemitem>. The walk through uses
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a custom partitioning scheme that carves out 60GB of space
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and labels it as LVM. The network uses
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<literal>FlatManager</literal> is the
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<literal>NetworkManager</literal> setting for
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OpenStack Compute (Nova).</para>
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<para>The network mode does not interfere with the way cinder works, but networking must be set
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up for cinder to work. For details, see <xref linkend="ch_networking"/>.</para>
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<para>To set up Compute to use volumes, ensure that Block
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Storage is installed along with lvm2. This guide describes how to:</para>
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<para>
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<itemizedlist>
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<listitem>
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<para>Troubleshoot your installation.</para>
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</listitem>
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<listitem>
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<para>Back up your Compute volumes.</para>
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</listitem>
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</itemizedlist>
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</para>
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<section xml:id="boot-from-volume">
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<title>Boot from volume</title>
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<para>In some cases, instances can be stored and run from
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inside volumes. For information, see the <link
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xlink:href="http://docs.openstack.org/user-guide/content/boot_from_volume.html"
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>Launch an instance from a volume</link> section in the
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<link xlink:href="http://docs.openstack.org/user-guide/content/"><citetitle>OpenStack End User
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Guide</citetitle></link>.</para>
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</section>
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<?hard-pagebreak?>
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<xi:include href="section_multi_backend.xml"/>
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<xi:include href="section_backup-block-storage-disks.xml"/>
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<xi:include href="section_volume-migration.xml"/>
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</section>
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<section xml:id="troubleshooting-cinder-install">
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<title>Troubleshooting your installation</title>
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<para>This section contains a few useful tips for troubleshoting
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your Block Storage installation</para>
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<xi:include href="section_block_storage_troubleshooting.xml"/>
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<xi:include href="section_ts_cinder_config.xml"/>
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<xi:include href="section_ts_multipath_warn.xml"/>
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<xi:include href="section_ts_vol_attach_miss_sg_scan.xml"/>
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</section>
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</chapter>
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