GPFS Cinder Volume Driver documentation.

This is the initial version of GPFS cinder driver documentatation for
avana release.  Update to use included config flag table.

Change-Id: I923e4525ce6a9b1277f3571ad5a0ca03785a57b5
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Bill Owen 2013-09-17 14:39:41 -07:00
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<section xml:id="GPFS-driver" 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">
<title>IBM GPFS Volume Driver</title>
<para>The General Parallel File System (GPFS) is a cluster file system that provides concurrent
access to file systems from multiple nodes. The storage provided by these nodes can be
direct attached, network attached, SAN attached or a combination of these methods. GPFS
provides many features beyond common data access including data replication, policy based
storage management, and space efficient file snapshot and clone operations.</para>
<section xml:id="GPFS-driver-background">
<title>How the GPFS Driver Works</title>
<para>This driver enables the use of GPFS in a similar fashion as the NFS driver. With the
GPFS driver, instances do not actually access a storage device at the block level.
Instead, volume backing files are created in a GPFS file system and mapped to instances,
which emulate a block device. </para>
<para>
<note>
<para>GPFS software must be installed and running on nodes where Cinder volume and
Nova compute services are running in the OpenStack environment. A GPFS file
system must also be created and mounted on these nodes before starting the
<literal>cinder-volume</literal> service. The details of these GPFS specific
steps are covered in GPFS Administration documentation. </para>
</note>
</para>
<para>Optionally, Glance can be configured to store images on a GPFS file system. When
Cinder volumes are created from Glance images, if both image and volume data reside in
the same GPFS file system, the data from image files is moved efficiently to Cinder
volumes using copy on write optimization strategy.</para>
</section>
<section xml:id="GPFS-driver-options">
<title>Enabling the GPFS Driver </title>
<para>To use Cinder with the GPFS driver, first set the <literal>volume_driver</literal> in
<filename>cinder.conf</filename>:</para>
<programlisting>volume_driver = cinder.volume.drivers.gpfs.GPFSDriver</programlisting>
<para>The following table contains the configuration options supported by the GPFS
driver.</para>
<xi:include href="../../../common/tables/cinder-gpfs_volume.xml"/>
<note>
<para>The flag <literal>gpfs_images_share_mode</literal> is only valid if the Image service
is configured to use GPFS with <literal>gpfs_images_dir</literal> flag. Also note,
when the value of this flag is <literal>copy_on_write</literal>, the paths
specified by the flags <literal>gpfs_mount_point_base</literal> and
<literal>gpfs_images_dir</literal> must both reside in the same GPFS file system
and in the same GPFS fileset.
</para>
</note>
</section>
<section xml:id="GPFS-volume-options">
<title>Volume Creation Options</title>
<para>It is possible to specify additional volume configuration options on a per-volume
basis by specifiying volume metadata. The volume is created using the specified options.
Changing the metadata after the volume is created has no effect. The following table
lists the volume creation options supported by the GPFS volume driver.</para>
<table frame="all">
<title>List of Volume Creation Options for GPFS Volume Driver:</title>
<tgroup cols="2">
<colspec colname="c1" colnum="1" colwidth="1*"/>
<colspec colname="c2" colnum="2" colwidth="1.74*"/>
<thead>
<row>
<entry>Metadata Item Name</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>fstype</literal></entry>
<entry>The driver will create a file system or swap area on the new volume.
If <literal>fstype=swap</literal> is specified, the mkswap command is
used to create a swap area. Otherwise the mkfs command is passed the
specified type, for example ext3, ext4, etc.</entry>
</row>
<row>
<entry><literal>fslabel</literal></entry>
<entry>The driver will set the file system label for the file system
specified by fstype option. This value is only used if fstype is
specified.</entry>
</row>
<row>
<entry><literal>data_pool_name</literal></entry>
<entry>
<para>The driver will assign the volume file to the specified GPFS
storage pool. Note that the GPFS storage pool must already be
created.</para>
</entry>
</row>
<row>
<entry><literal>replicas</literal></entry>
<entry>
<para>Specify how many copies of the volume file to create. Valid values
are 1, 2, and, for GPFS V3.5.0.7 and later, 3. This value cannot be
greater than the value of the MaxDataReplicas attribute of the file
system.</para>
</entry>
</row>
<row>
<entry><literal>dio</literal></entry>
<entry>
<para>Enable or disable the Direct I/O caching policy for the volume
file. Valid values are "yes" and "no".</para>
</entry>
</row>
<row>
<entry><literal>write_affinity_depth</literal></entry>
<entry>
<para>Specify the allocation policy to be used for the volume file. Note
that this option only works if "allow-write-affinity" is set for the
GPFS data pool. </para>
</entry>
</row>
<row>
<entry><literal>block_group_factor</literal></entry>
<entry>
<para>Specify how many blocks are laid out sequentially in the volume
file to behave like a single large block. This option only works if
"allow-write-affinity" is set for the GPFS data pool. </para>
</entry>
</row>
<row>
<entry><literal>write_affinity_failure_group</literal></entry>
<entry>
<para>Specify the range of nodes (in GPFS shared nothing architecture)
where replicas of blocks in the volume file are to be written. See
GPFS Administration and Programming Reference guide for more details
on this option.</para>
</entry>
</row>
</tbody>
</tgroup>
</table>
<simplesect>
<title>Example Using Volume Creation Options</title>
<para>This example shows the creation of a 50GB volume with an ext4 filesystem labeled
<literal>newfs</literal>and direct IO enabled:</para>
<screen><prompt>$</prompt><userinput>cinder create --metadata fstype=ext4 fslabel=newfs dio=yes --display-name volume_1 50</userinput> </screen>
</simplesect>
</section>
<section xml:id="GPFS-operational-notes">
<title>Operational Notes for GPFS Driver</title>
<simplesect>
<title>Snapshots and Clones</title>
<para>Volume snapshots are implemented using the GPFS file clone feature. Whenever a new
snapshot is created, the snapshot file is efficiently created as a read-only clone
parent of the volume, and the volume file uses copy on write optimization strategy
to minimize data movement. </para>
<para>Similarly when a new volume is created from a snapshot or from an existing volume,
the same approach is taken. The same approach is also used when a new volume is
created from a Glance image, if the source image is in raw format, and
<literal>gpfs_images_share_mode</literal> is set to
<literal>copy_on_write</literal>.</para>
</simplesect>
</section>
</section>

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<xi:include href="drivers/hp-3par-driver.xml"/>
<xi:include href="drivers/hp-lefthand-driver.xml"/>
<xi:include href="drivers/huawei-storage-driver.xml"/>
<xi:include href="drivers/ibm-gpfs-volume-driver.xml"/>
<xi:include href="drivers/ibm-storwize-svc-driver.xml"/>
<xi:include href="drivers/netapp-volume-driver.xml"/>
<xi:include href="drivers/nexenta-volume-driver.xml"/>