Dell EMC XtremIO Block Storage driver

The high performance XtremIO All Flash Array (AFA) offers Block Storage services to OpenStack. Using the driver, OpenStack Block Storage hosts can connect to an XtremIO Storage cluster.

This section explains how to configure and connect the block storage nodes to an XtremIO storage cluster.

Support matrix

XtremIO version 4.x is supported.

Supported operations

  • Create, delete, clone, attach, and detach volumes.

  • Create and delete volume snapshots.

  • Create a volume from a snapshot.

  • Copy an image to a volume.

  • Copy a volume to an image.

  • Extend a volume.

  • Manage and unmanage a volume.

  • Manage and unmanage a snapshot.

  • Get volume statistics.

  • Create, modify, delete, and list consistency groups.

  • Create, modify, delete, and list snapshots of consistency groups.

  • Create consistency group from consistency group or consistency group snapshot.

  • Volume Migration (host assisted)

XtremIO Block Storage driver configuration

Edit the cinder.conf file by adding the configuration below under the [DEFAULT] section of the file in case of a single back end or under a separate section in case of multiple back ends (for example [XTREMIO]). The configuration file is usually located under the following path /etc/cinder/cinder.conf.

Description of XtremIO configuration options

Configuration option = Default value

Description

xtremio_array_busy_retry_count = 5

(Integer) Number of retries in case array is busy

xtremio_array_busy_retry_interval = 5

(Integer) Interval between retries in case array is busy

xtremio_clean_unused_ig = False

(Boolean) Should the driver remove initiator groups with no volumes after the last connection was terminated. Since the behavior till now was to leave the IG be, we default to False (not deleting IGs without connected volumes); setting this parameter to True will remove any IG after terminating its connection to the last volume.

xtremio_cluster_name = <>

(String) XMS cluster id in multi-cluster environment

xtremio_volumes_per_glance_cache = 100

(Integer) Number of volumes created from each cached glance image

For a configuration example, refer to the configuration Configuration example.

XtremIO driver name

Configure the driver name by setting the following parameter in the cinder.conf file:

  • For iSCSI:

    volume_driver = cinder.volume.drivers.dell_emc.xtremio.XtremIOISCSIDriver
    
  • For Fibre Channel:

    volume_driver = cinder.volume.drivers.dell_emc.xtremio.XtremIOFibreChannelDriver
    

XtremIO management server (XMS) IP

To retrieve the management IP, use the show-xms CLI command.

Configure the management IP by adding the following parameter:

san_ip = XMS Management IP

XtremIO cluster name

In XtremIO version 4.0, a single XMS can manage multiple cluster back ends. In such setups, the administrator is required to specify the cluster name (in addition to the XMS IP). Each cluster must be defined as a separate back end.

To retrieve the cluster name, run the show-clusters CLI command.

Configure the cluster name by adding the following parameter:

xtremio_cluster_name = Cluster-Name

Note

When a single cluster is managed in XtremIO version 4.0, the cluster name is not required.

XtremIO user credentials

OpenStack Block Storage requires an XtremIO XMS user with administrative privileges. XtremIO recommends creating a dedicated OpenStack user account that holds an administrative user role.

Refer to the XtremIO User Guide for details on user account management.

Create an XMS account using either the XMS GUI or the add-user-account CLI command.

Configure the user credentials by adding the following parameters:

san_login = XMS username
san_password = XMS username password

Multiple back ends

Configuring multiple storage back ends enables you to create several back-end storage solutions that serve the same OpenStack Compute resources.

When a volume is created, the scheduler selects the appropriate back end to handle the request, according to the specified volume type.

Setting thin provisioning and multipathing parameters

To support thin provisioning and multipathing in the XtremIO Array, the following parameters from the Nova and Cinder configuration files should be modified as follows:

  • Thin Provisioning

    All XtremIO volumes are thin provisioned. The default value of 20 should be maintained for the max_over_subscription_ratio parameter.

    The use_cow_images parameter in the nova.conf file should be set to False as follows:

    use_cow_images = False
    
  • Multipathing

    The use_multipath_for_image_xfer parameter in the cinder.conf file should be set to True for each backend or in [backend_defaults] section as a common configuration for all backends.

    use_multipath_for_image_xfer = True
    

Image service optimization

Limit the number of copies (XtremIO snapshots) taken from each image cache.

xtremio_volumes_per_glance_cache = 100

The default value is 100. A value of 0 ignores the limit and defers to the array maximum as the effective limit.

SSL certification

To enable SSL certificate validation, modify the following option in the cinder.conf file:

driver_ssl_cert_verify = true

By default, SSL certificate validation is disabled.

To specify a non-default path to CA_Bundle file or directory with certificates of trusted CAs:

driver_ssl_cert_path = Certificate path

Configuring CHAP

The XtremIO Block Storage driver supports CHAP initiator authentication and discovery.

If CHAP initiator authentication is required, set the CHAP Authentication mode to initiator.

To set the CHAP initiator mode using CLI, run the following XMCLI command:

$ modify-chap chap-authentication-mode=initiator

If CHAP initiator discovery is required, set the CHAP discovery mode to initiator.

To set the CHAP initiator discovery mode using CLI, run the following XMCLI command:

$ modify-chap chap-discovery-mode=initiator

The CHAP initiator modes can also be set via the XMS GUI.

Refer to XtremIO User Guide for details on CHAP configuration via GUI and CLI.

The CHAP initiator authentication and discovery credentials (username and password) are generated automatically by the Block Storage driver. Therefore, there is no need to configure the initial CHAP credentials manually in XMS.

Configuration example

You can update the cinder.conf file by editing the necessary parameters as follows:

[Default]
enabled_backends = XtremIO

[XtremIO]
volume_driver = cinder.volume.drivers.dell_emc.xtremio.XtremIOFibreChannelDriver
san_ip = XMS_IP
xtremio_cluster_name = Cluster01
san_login = XMS_USER
san_password = XMS_PASSWD
volume_backend_name = XtremIOAFA