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Dell EMC SC Series Fibre Channel and iSCSI drivers
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The Dell EMC Storage Center volume driver interacts with configured Storage
Center arrays.

The Dell EMC Storage Center driver manages a Storage Center array via the
Dell EMC Storage Manager (DSM) Data Collector or by directly connecting to
the Storage Center at the cost of replication and Live Volume functionality.
Also note that the directly connecting to the Storage Center is only
supported with Storage Center OS 7.1.1 or later. Any version of Storage
Center OS supported by DSM is supported if connecting via the Data
Collector.

Driver configuration settings and Storage Center options are defined in the
``cinder.conf`` file.

Prerequisites:

- Storage Center OS version 7.1.1 or later and OpenStack Ocata or later
  must be used if connecting directly to the Storage Center.
- Dell EMC Storage Manager 2015 R1 or later if connecting through DSM.

Supported operations
~~~~~~~~~~~~~~~~~~~~

The Dell EMC Storage Center volume driver provides the following Cinder
volume operations:

-  Create, delete, attach (map), and detach (unmap) volumes.
-  Create, list, and delete volume snapshots.
-  Create a volume from a snapshot.
-  Copy an image to a volume.
-  Copy a volume to an image.
-  Clone a volume.
-  Extend a volume.
-  Create, delete, list and update a consistency group.
-  Create, delete, and list consistency group snapshots.
-  Manage an existing volume.
-  Replication (Requires DSM.)
-  Failover-host for replicated back ends. (Requires DSM.)
-  Create a replication using Live Volume. (Requires DSM.)

Extra spec options
~~~~~~~~~~~~~~~~~~

Volume type extra specs can be used to enable a variety of Dell EMC Storage
Center options. Selecting Storage Profiles, Replay Profiles, enabling
replication, replication options including Live Volume and Active Replay
replication. (Replication options are available when connected via DSM.)

Storage Profiles control how Storage Center manages volume data. For a
given volume, the selected Storage Profile dictates which disk tier
accepts initial writes, as well as how data progression moves data
between tiers to balance performance and cost. Predefined Storage
Profiles are the most effective way to manage data in Storage Center.

By default, if no Storage Profile is specified in the volume extra
specs, the default Storage Profile for the user account configured for
the Block Storage driver is used. The extra spec key
``storagetype:storageprofile`` with the value of the name of the Storage
Profile on the Storage Center can be set to allow to use Storage
Profiles other than the default.

For ease of use from the command line, spaces in Storage Profile names
are ignored. As an example, here is how to define two volume types using
the ``High Priority`` and ``Low Priority`` Storage Profiles:

.. code-block:: console

    $ openstack volume type create "GoldVolumeType"
    $ openstack volume type set --property storagetype:storageprofile=highpriority "GoldVolumeType"
    $ openstack volume type create "BronzeVolumeType"
    $ openstack volume type set --property storagetype:storageprofile=lowpriority "BronzeVolumeType"

Replay Profiles control how often the Storage Center takes a replay of a
given volume and how long those replays are kept. The default profile is
the ``daily`` profile that sets the replay to occur once a day and to
persist for one week.

The extra spec key ``storagetype:replayprofiles`` with the value of the
name of the Replay Profile or profiles on the Storage Center can be set
to allow to use Replay Profiles other than the default ``daily`` profile.

As an example, here is how to define a volume type using the ``hourly``
Replay Profile and another specifying both ``hourly`` and the default
``daily`` profile:

.. code-block:: console

    $ openstack volume type create "HourlyType"
    $ openstack volume type set --property storagetype:replayprofile=hourly "HourlyType"
    $ openstack volume type create "HourlyAndDailyType"
    $ openstack volume type set --property storagetype:replayprofiles=hourly,daily "HourlyAndDailyType"

Note the comma separated string for the ``HourlyAndDailyType``.

Replication for a given volume type is enabled via the extra spec
``replication_enabled``.

To create a volume type that specifies only replication enabled back ends:

.. code-block:: console

    $ openstack volume type create "ReplicationType"
    $ openstack volume type set --property replication_enabled='<is> True' "ReplicationType"

Extra specs can be used to configure replication. In addition to the Replay
Profiles above, ``replication:activereplay`` can be set to enable replication
of the volume's active replay. And the replication type can be changed to
synchronous via the ``replication_type`` extra spec can be set.

To create a volume type that enables replication of the active replay:

.. code-block:: console

    $ openstack volume type create "ReplicationType"
    $ openstack volume type key --property replication_enabled='<is> True' "ReplicationType"
    $ openstack volume type key --property replication:activereplay='<is> True' "ReplicationType"

To create a volume type that enables synchronous replication :

.. code-block:: console

    $ openstack volume type create "ReplicationType"
    $ openstack volume type key --property replication_enabled='<is> True' "ReplicationType"
    $ openstack volume type key --property replication_type='<is> sync' "ReplicationType"

To create a volume type that enables replication using Live Volume:

.. code-block:: console

    $ openstack volume type create "ReplicationType"
    $ openstack volume type key --property replication_enabled='<is> True' "ReplicationType"
    $ openstack volume type key --property replication:livevolume='<is> True' "ReplicationType"

If QOS options are enabled on the Storage Center they can be enabled via extra
specs. The name of the Volume QOS can be specified via the
``storagetype:volumeqos`` extra spec. Likewise the name of the Group QOS to
use can be specified via the ``storagetype:groupqos`` extra spec. Volumes
created with these extra specs set will be added to the specified QOS groups.

To create a volume type that sets both Volume and Group QOS:

.. code-block:: console

    $ openstack volume type create "StorageCenterQOS"
    $ openstack volume type key --property 'storagetype:volumeqos'='unlimited' "StorageCenterQOS"
    $ openstack volume type key --property 'storagetype:groupqos'='limited' "StorageCenterQOS"

Data reduction profiles can be specified in the
``storagetype:datareductionprofile`` extra spec. Available options are None,
Compression, and Deduplication. Note that not all options are available on
every Storage Center.

To create volume types that support no compression, compression, and
deduplication and compression respectively:

.. code-block:: console

    $ openstack volume type create "NoCompressionType"
    $ openstack volume type key --property 'storagetype:datareductionprofile'='None' "NoCompressionType"
    $ openstack volume type create "CompressedType"
    $ openstack volume type key --property 'storagetype:datareductionprofile'='Compression' "CompressedType"
    $ openstack volume type create "DedupType"
    $ openstack volume type key --property 'storagetype:datareductionprofile'='Deduplication' "DedupType"

Note: The default is no compression.

iSCSI configuration
~~~~~~~~~~~~~~~~~~~

Use the following instructions to update the configuration file for iSCSI:

.. code-block:: ini

    default_volume_type = delliscsi
    enabled_backends = delliscsi

    [delliscsi]
    # Name to give this storage back-end
    volume_backend_name = delliscsi
    # The iSCSI driver to load
    volume_driver = cinder.volume.drivers.dell_emc.sc.storagecenter_iscsi.SCISCSIDriver
    # IP address of the DSM or the Storage Center if attaching directly.
    san_ip = 172.23.8.101
    # DSM user name
    san_login = Admin
    # DSM password
    san_password = secret
    # The Storage Center serial number to use
    dell_sc_ssn = 64702

    # ==Optional settings==

    # The DSM API port
    dell_sc_api_port = 3033
    # Server folder to place new server definitions
    dell_sc_server_folder = devstacksrv
    # Volume folder to place created volumes
    dell_sc_volume_folder = devstackvol/Cinder

Fibre Channel configuration
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use the following instructions to update the configuration file for fibre
channel:

.. code-block:: ini

    default_volume_type = dellfc
    enabled_backends = dellfc

    [dellfc]
    # Name to give this storage back-end
    volume_backend_name = dellfc
    # The FC driver to load
    volume_driver = cinder.volume.drivers.dell_emc.sc.storagecenter_fc.SCFCDriver

    # IP address of the DSM or the Storage Center if attaching directly.
    san_ip = 172.23.8.101
    # DSM user name
    san_login = Admin
    # DSM password
    san_password = secret
    # The Storage Center serial number to use
    dell_sc_ssn = 64702

    # ==Optional settings==

    # The DSM API port
    dell_sc_api_port = 3033
    # Server folder to place new server definitions
    dell_sc_server_folder = devstacksrv
    # Volume folder to place created volumes
    dell_sc_volume_folder = devstackvol/Cinder

Dual DSM
~~~~~~~~

It is possible to specify a secondary DSM to use in case the primary DSM fails.

Configuration is done through the cinder.conf. Both DSMs have to be
configured to manage the same set of Storage Centers for this backend. That
means the dell_sc_ssn and any Storage Centers used for replication or Live
Volume.

Add network and credential information to the backend to enable Dual DSM.

.. code-block:: ini

    [dell]
    # The IP address and port of the secondary DSM.
    secondary_san_ip = 192.168.0.102
    secondary_sc_api_port = 3033
    # Specify credentials for the secondary DSM.
    secondary_san_login = Admin
    secondary_san_password = secret

The driver will use the primary until a failure. At that point it will attempt
to use the secondary. It will continue to use the secondary until the volume
service is restarted or the secondary fails at which point it will attempt to
use the primary.

Note: Requires two DSM Data Collectors.

Replication configuration
~~~~~~~~~~~~~~~~~~~~~~~~~

Add the following to the back-end specification to specify another Storage
Center to replicate to.

.. code-block:: ini

    [dell]
    replication_device = target_device_id: 65495, qosnode: cinderqos

The ``target_device_id`` is the SSN of the remote Storage Center and the
``qosnode`` is the QoS Node setup between the two Storage Centers.

Note that more than one ``replication_device`` line can be added. This will
slow things down, however.

A volume is only replicated if the volume is of a volume-type that has
the extra spec ``replication_enabled`` set to ``<is> True``.

Warning: replication_device requires DSM. If this is on a backend that
is directly connected to the Storage Center the driver will not load
as it is unable to meet the replication requirement.

Replication notes
~~~~~~~~~~~~~~~~~

This driver supports both standard replication and Live Volume (if supported
and licensed). The main difference is that a VM attached to a Live Volume is
mapped to both Storage Centers. In the case of a failure of the primary Live
Volume still requires a failover-host to move control of the volume to the
second controller.

Existing mappings should work and not require the instance to be remapped but
it might need to be rebooted.

Live Volume is more resource intensive than replication. One should be sure
to plan accordingly.

Failback
~~~~~~~~

The failover-host command is designed for the case where the primary system is
not coming back. If it has been executed and the primary has been restored it
is possible to attempt a failback.

Simply specify default as the backend_id.

.. code-block:: console

    $ cinder failover-host cinder@delliscsi --backend_id default

Non trivial heavy lifting is done by this command. It attempts to recover as
best it can but if things have diverged too far it can only do so much. It is
also a one time only command so do not reboot or restart the service in the
middle of it.

Failover and failback are significant operations under OpenStack Cinder. Be
sure to consult with support before attempting.

Server type configuration
~~~~~~~~~~~~~~~~~~~~~~~~~

This option allows one to set a default Server OS type to use when creating
a server definition on the Dell EMC Storage Center.

When attaching a volume to a node the Dell EMC Storage Center driver creates a
server definition on the storage array. This definition includes a Server OS
type. The type used by the Dell EMC Storage Center cinder driver is
"Red Hat Linux 6.x". This is a modern operating system definition that supports
all the features of an OpenStack node.

Add the following to the back-end specification to specify the Server OS to use
when creating a server definition. The server type used must come from the drop
down list in the DSM.

.. code-block:: ini

    [dell]
    dell_server_os = 'Red Hat Linux 7.x'

Note that this server definition is created once. Changing this setting after
the fact will not change an existing definition. The selected Server OS does
not have to match the actual OS used on the node.

Excluding a domain
~~~~~~~~~~~~~~~~~~

This option excludes a Storage Center ISCSI fault domain from the ISCSI
properties returned by the initialize_connection call. This only applies to
the ISCSI driver.

Add the excluded_domain_ip option into the backend config for each fault domain
to be excluded. This option takes the specified Target IPv4 Address listed
under the fault domain. Older versions of DSM (EM) may list this as the Well
Known IP Address.

Add the following to the back-end specification to exclude the domains at
172.20.25.15 and 172.20.26.15.

.. code-block:: ini

    [dell]
    excluded_domain_ip=172.20.25.15
    excluded_domain_ip=172.20.26.15

Setting Dell EMC SC REST API timeouts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The user can specify timeouts for Dell EMC SC REST API calls.

To set the timeout for ASYNC REST API calls in seconds.

.. code-block:: ini

    [dell]
    dell_api_async_rest_timeout=15

To set the timeout for SYNC REST API calls in seconds.

.. code-block:: ini

    [dell]
    dell_api_sync_rest_timeout=30

Generally these should not be set without guidance from Dell EMC support.

Driver options
~~~~~~~~~~~~~~

The following table contains the configuration options specific to the
Dell EMC Storage Center volume driver.

.. config-table::
   :config-target: SC Series

   cinder.volume.drivers.dell_emc.sc.storagecenter_common
