Merge "VMAX doc - Queens feature documentation"
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@ -1077,12 +1077,14 @@ Volume replication support
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Configure the source and target arrays
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--------------------------------------
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#. Configure a synchronous SRDF group between the chosen source and target
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#. Configure an SRDF group between the chosen source and target
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arrays for the VMAX cinder driver to use. The source array must correspond
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with the ``<Array>`` entry in the VMAX XML file.
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with the 'vmax_array' entry in the cinder.conf (or the ``<Array>`` entry
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in the VMAX XML file for legacy setups).
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#. Select both the director and the ports for the SRDF emulation to use on
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both sides. Bear in mind that network topology is important when choosing
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director endpoints. Currently, the only supported mode is `Synchronous`.
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director endpoints. Supported modes are `Synchronous`, `Asynchronous`,
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and `Metro`.
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.. note::
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@ -1095,10 +1097,16 @@ Configure the source and target arrays
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be automatically failed over to the target array, but administrator
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intervention would be required to either; configure the target (remote)
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array as local to the current Unisphere server (if it is a stand-alone
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server), or enter the details to the XML file of a second Unisphere
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server, which is locally connected to the target array (for example, the
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embedded management Unisphere server of the target array), and restart
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the cinder volume service.
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server), or enter the details of a second Unisphere server to the
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``cinder.conf``, which is locally connected to the target array (for
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example, the embedded management Unisphere server of the target array),
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and restart the cinder volume service.
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.. note::
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If you are setting up an SRDF/Metro configuration, it is recommended that
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you configure a Witness or vWitness for bias management. Please see
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https://www.emc.com/collateral/technical-documentation/h14556-vmax3-srdf-metro-overview-and-best-practices-tech-note.pdf
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#. Enable replication in ``/etc/cinder/cinder.conf``.
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To enable the replication functionality in VMAX cinder driver, it is
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@ -1109,17 +1117,14 @@ Configure the source and target arrays
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value pairs.
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.. code-block:: console
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[DEFAULT]
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enabled_backends = VMAX_FC_REPLICATION
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.. code-block:: console
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[VMAX_FC_REPLICATION]
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volume_driver = cinder.volume.drivers.dell_emc.vmax_fc.VMAXFCDriver
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cinder_dell_emc_config_file = /etc/cinder/cinder_dell_emc_config_VMAX_FC_REPLICATION.xml
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volume_backend_name = VMAX_FC_REPLICATION
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replication_device = target_device_id:000197811111, remote_port_group:os-failover-pg, remote_pool:SRP_1, rdf_group_label: 28_11_07, allow_extend:False
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replication_device = target_device_id:000197811111, remote_port_group:os-failover-pg, remote_pool:SRP_1, rdf_group_label: 28_11_07,
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allow_extend:False, mode:Metro, metro_use_bias:False, allow_delete_metro:False
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* ``target_device_id`` is a unique VMAX array serial number of the target
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array. For full failover functionality, the source and target VMAX arrays
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@ -1130,9 +1135,12 @@ Configure the source and target arrays
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of a failover. Make sure that this portgroup contains either all FC or
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all iSCSI port groups (for a given back end), as appropriate for the
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configured driver (iSCSI or FC).
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* ``remote_pool`` is the unique pool name for the given target array.
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* ``rdf_group_label`` is the name of a VMAX SRDF group (Synchronous) that
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has been pre-configured between the source and target arrays.
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* ``rdf_group_label`` is the name of a VMAX SRDF group that has been pre-configured
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between the source and target arrays.
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* ``allow_extend`` is a flag for allowing the extension of replicated volumes.
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To extend a volume in an SRDF relationship, this relationship must first be
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broken, both the source and target volumes are then independently extended,
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@ -1143,8 +1151,21 @@ Configure the source and target arrays
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As the SRDF link must be severed, due caution should be exercised when
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performing this operation. If absolutely necessary, only one source and
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target pair should be extended at a time.
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In Queens, the underlying VMAX architecture will support extending
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source and target volumes without having to sever links.
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.. note::
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It is not currently possible to extend SRDF/Metro protected volumes.
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* ``mode`` is the required replication mode. Options are 'Synchronous',
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'Asynchronous', and 'Metro'. This defaults to 'Synchronous'.
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* ``metro_use_bias`` is a flag to indicate if 'bias' protection should be
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used instead of Witness. This defaults to False.
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* ``allow_delete_metro`` is a flag to indicate if metro devices can be deleted.
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All Metro devices in an RDF group need to be managed together, so in order to delete
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one of the pairings, the whole group needs to be first suspended. Because of this,
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we require this flag to be explicitly set. This flag defaults to False.
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.. note::
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Service Level and Workload: An attempt will be made to create a storage
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@ -1177,14 +1198,18 @@ Volume replication interoperability with other features
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Most features are supported, except for the following:
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* There is no OpenStack Generic Volume Group support for replication-enabled
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VMAX volumes.
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* Replication Group operations are available for volumes in Synchronous mode only.
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* Storage-assisted retype operations on replication-enabled VMAX volumes
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(moving from a non-replicated type to a replicated-type and vice-versa.
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Moving to another service level/workload combination, for example) are
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not supported.
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* It is not currently possible to extend SRDF/Metro protected volumes.
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If a bigger volume size is required for a SRDF/Metro protected volume, this can be
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achieved by cloning the original volume and choosing a larger size for the new
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cloned volume.
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* The image volume cache functionality is supported (enabled by setting
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``image_volume_cache_enabled = True``), but one of two actions must be taken
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when creating the cached volume:
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@ -1194,7 +1219,8 @@ Most features are supported, except for the following:
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For example, if the minimum size disk to hold an image is 5GB, create
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the first boot volume as 5GB.
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* Alternatively, ensure that the ``allow_extend`` option in the
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``replication_device parameter`` is set to ``True``.
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``replication_device parameter`` is set to ``True`` (Please note that it is
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not possible to extend SRDF/Metro protected volumes).
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This is because the initial boot volume is created at the minimum required
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size for the requested image, and then extended to the user specified size.
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@ -1218,6 +1244,33 @@ using the same command and specifying ``--backend_id default``:
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$ cinder failover-host cinder_host@VMAX_FC_REPLICATION --backend_id default
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.. note::
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Failover and Failback operations are not applicable in Metro configurations.
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Asynchonous and Metro replication management groups
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---------------------------------------------------
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Asynchronous and Metro volumes in an RDF session, i.e. belonging to an SRDF
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group, must be managed together for RDF operations (although there is a
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``consistency exempt`` option for creating and deleting pairs in an Async
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group). To facilitate this management, we create an internal RDF management
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storage group on the backend. It is crucial for correct management that the
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volumes in this storage group directly correspond to the volumes in the RDF
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group. For this reason, it is imperative that the RDF group specified in the
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``cinder.conf`` is for the exclusive use by this cinder backend.
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Metro support
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-------------
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SRDF/Metro is a High Availabilty solution. It works by masking both sides of
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the RDF relationship to the host, and presenting all paths to the host,
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appearing that they all point to the one device. In order to the do this,
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there needs to be multipath software running to manage writing to the multiple
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paths.
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Volume retype - storage assisted volume migration
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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@ -1243,9 +1296,12 @@ Generic volume group support
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Generic volume group operations are performed through the CLI using API
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version 3.1x of the cinder API. Generic volume groups are multi-purpose
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groups which can be used for various features. The only feature supported
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currently by the VMAX plugin is the ability to take group snapshots which
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are consistent based on the group specs. Generic volume groups are a
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groups which can be used for various features. The VMAX plugin supports
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consistent group snapshots and replication groups. Consistent group
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snapshots allows the user to take group snapshots which
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are consistent based on the group specs. Replication groups allow for
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tenant facing APIs to enable and disable replication, and to failover
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and failback, a group of volumes. Generic volume groups are a
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replacement for the consistency groups.
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Consistent group snapshot
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@ -1255,9 +1311,10 @@ For creating a consistent group snapshot, a group-spec, having the key
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``consistent_group_snapshot_enabled`` set to ``<is> True``, should be set
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on the group. Similarly the same key should be set on any volume type which
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is specified while creating the group. The VMAX plugin doesn't support
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creating/managing a group which doesn't have this group-spec set. If this key
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is not set on the group-spec then the generic volume group will be
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created/managed by cinder (not the VMAX plugin).
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creating/managing a group which doesn't have this (or replication group spec,
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see below) group-spec set. If one of these keys are not set on the group-spec,
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then the generic volume group will be created/managed by cinder (not the VMAX
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plugin).
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.. note::
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@ -1269,6 +1326,26 @@ created/managed by cinder (not the VMAX plugin).
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For creating consistent group snapshots, no changes are required to be
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done to the ``/etc/cinder/policy.json``.
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Replication Groups
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------------------
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To create a replication group, a group-spec, having the key
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``consistent_group_replication_enabled`` set to ``<is> True``, should be set
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on the group. Any volume types sepcified while creating the group must also
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be replication-enabled, i.e. have the the extra spec 'replication-enabled' set
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to ``<is> True``. Please note that only Synchronous replication is supported
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for use with Replication Groups. When a volume is created into a replication
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group, replication is on by default. The "disable_replication" api suspends
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I/O traffic on the devices, but does NOT remove replication for the group.
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The "enable_replication" api resumes I/O traffic on the RDF links. The
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"failover_group" api allows a group to be failed over and back without
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failing over the entire host. See below for usage.
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.. note::
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A generic volume group can be both consistent group snapshot enabled and
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consistent group replication enabled.
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Storage Group Names
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-------------------
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@ -1380,6 +1457,31 @@ Operations
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cinder --os-volume-api-version 3.13 group-delete --delete-volumes GROUP
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- Enable group replication
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.. code-block:: console
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cinder --os-volume-api-version 3.38 group-enable-replication GROUP
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- Disable group replication
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.. code-block:: console
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cinder --os-volume-api-version 3.38 group-disable-replication GROUP
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- Failover group
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.. code-block:: console
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cinder --os-volume-api-version 3.38 group-failover-replication GROUP
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- Failback group
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.. code-block:: console
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cinder --os-volume-api-version 3.38 group-failover-replication GROUP /
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--secondary-backend-id default
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Oversubscription support
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~~~~~~~~~~~~~~~~~~~~~~~~
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@ -1726,3 +1828,163 @@ Once unmanaged from OpenStack, the volume can still be retrieved using its
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device ID or OpenStack volume ID. Within Unisphere you will also notice that
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the 'OS-' prefix has been removed, this is another visual indication that
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the volume is no longer managed by OpenStack.
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Manage/Unmanage Snapshots
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Users can manage VMAX SnapVX snapshots into OpenStack if the source volume
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already exists in Cinder. Similarly, users will be able to unmanage OpenStack
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snapshots to remove them from Cinder but keep them on the storage backend.
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Set-up, restrictions and requirements:
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#. No additional settings or configuration is required to support this
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functionality.
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#. Manage/Unmanage snapshots requires SnapVX functionality support on VMAX.
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#. Manage/Unmanage Snapshots in OpenStack Cinder is only supported at present
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through Cinder CLI commands.
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#. It is only possible to manage or unmanage one snapshot at a time in Cinder.
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#. This functionality is not to be confused with the similarly named
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``manage and unmanage snapshots`` which details setting attributes of a
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given snapshot in Cinder.
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Manage SnapVX Snapshot
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----------------------
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It is possible to manage VMAX SnapVX snapshots into OpenStack, where the
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source volume from which the snapshot is taken already exists in, and is
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managed by OpenStack Cinder. The source volume may have been created in
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OpenStack Cinder, or it may have been managed in to OpenStack Cinder also.
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With the support of managing SnapVX snapshots included in OpenStack Queens,
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the restriction around managing SnapVX source volumes has been removed.
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.. note::
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It is not possible to manage into OpenStack SnapVX linked target volumes,
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or volumes which exist in a replication session.
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Requirements/Restrictions:
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#. The SnapVX source volume must be present in and managed by Cinder.
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#. The SnapVX snapshot name must not begin with ``OS-``.
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#. The SnapVX snapshot source volume must not be in a failed-over state.
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#. Managing a SnapVX snapshot will only be allowed if the snapshot has no
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linked target volumes.
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#. Managing a SnapVX snapshot which is smaller than the source volume is
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permitted as it is supported for create new volumes and restore from
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snapshot (the remainder of volume size is zeroed out).
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Command Structure:
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#. Identify your SnapVX snapshot for management on the VMAX, note the name.
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#. Ensure the source volume is already managed into OpenStack Cinder, note
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the device ID.
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#. Using the Cinder CLI, use the following command structure to manage a
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Snapshot into OpenStack Cinder:
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.. code-block:: console
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$ cinder snapshot-manage --id-type source-name
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[--name <name>]
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[--description <description>]
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[--metadata [<key=value> [<key=value> ...]]]
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<volume> <identifier>
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Positional arguments:
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- <volume> - Cinder volume which already exists in volume backend
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- <identifier> - Name of existing snapshot
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Optional arguments:
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- --name <name> - Snapshot name (Default=None)
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- --description <description> - Snapshot description (Default=None)
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- --metadata [<key=value> [<key=value> ...]]
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Metadata key=value pairs (Default=None)
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Example:
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.. code-block:: console
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$ cinder snapshot-manage --name SnapshotManaged
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--description "Managed Queens Feb18"
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0021A VMAXSnapshot
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Where:
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- The name in OpenStack after managing the SnapVX snapshot will be
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``SnapshotManaged``.
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- The snapshot will have the description ``Managed Queens Feb18``.
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- The source volume device ID is ``0021A``.
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- The name of the SnapVX snapshot on the VMAX backend is ``VMAXSnapshot``.
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Outcome:
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After the process of managing the Snapshot has completed, the SnapVX snapshot
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on the VMAX backend will be prefixed by the letters ``OS-``, leaving the
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snapshot in this example named ``OS-VMAXSnapshot``. The associated snapshot
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managed by Cinder will be present for use under the name ``SnapshotManaged``.
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Unmanage Cinder Snapshot
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~~~~~~~~~~~~~~~~~~~~~~~~
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Unmanaging a snapshot in Cinder is the process whereby the snapshot is removed
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from and no longer managed by Cinder, but it still exists on the storage
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backend. Unmanaging a SnapVX snapshot in OpenStack Cinder follows this
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behaviour, whereby after unmanaging a VMAX SnapVX snapshot from Cinder, the
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snapshot is removed from OpenStack but is still present for use on the VMAX
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backend.
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Requirements/Restrictions:
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- The SnapVX source volume must not be in a failed over state.
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Command Structure:
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Identify the SnapVX snapshot you want to unmanage from OpenStack cinder, note
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the snapshot name or ID as specified by Cinder. Using the Cinder CLI use the
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following command structure to unmanage the SnapVX snapshot from Cinder:
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.. code-block:: console
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$ cinder snapshot-unmanage <snapshot>
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Positional arguments:
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- <snapshot> - Cinder snapshot name or ID.
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Example:
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.. code-block:: console
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$ cinder snapshot-unmanage SnapshotManaged
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Where:
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- The SnapVX snapshot name in OpenStack Cinder is SnapshotManaged.
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After the process of unmanaging the SnapVX snapshot in Cinder, the snapshot on
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the VMAX backend will have the ``OS-`` prefix removed to indicate it is no
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longer OpenStack managed. In the example above, the snapshot after unmanaging
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from OpenStack will be named ``VMAXSnapshot`` on the storage backend.
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