Dell PowerFlex Storage driver¶

Official PowerFlex documentation¶

To find the PowerFlex documentation:

1. Go to the PowerFlex product documentation page.

2. On the page, search for the relevant PowerFlex version.

Supported PowerFlex or VxFlex OS Versions¶

The Dell PowerFlex Block Storage driver has been tested against the following versions of VxFlex OS and PowerFlex and found to be compatible:

• VxFlex OS 3.0.x

• PowerFlex 3.5.x

• PowerFlex 3.6.0

Please consult the Official PowerFlex documentation to determine supported operating systems for each version of PowerFlex or VxFlex OS.

Deployment prerequisites¶

• The PowerFlex Gateway must be installed and accessible in the network. For installation steps, refer to the Preparing the installation Manager and the Gateway section in PowerFlex Deployment Guide. See Official PowerFlex documentation.

• PowerFlex Storage Data Client (SDC) must be installed on all OpenStack nodes.

Supported operations¶

• Create, delete, clone, attach, detach, migrate, manage, and unmanage volumes

• Create, delete, manage, and unmanage volume snapshots

• Create a volume from a snapshot

• Revert a volume to a snapshot

• Copy an image to a volume

• Copy a volume to an image

• Extend a volume

• Get volume statistics

• Create, list, update, and delete consistency groups

• Create, list, update, and delete consistency group snapshots

• OpenStack replication v2.1 support

PowerFlex driver name¶

Configure the driver name by adding the following parameter:

volume_driver = cinder.volume.drivers.dell_emc.powerflex.driver.PowerFlexDriver

PowerFlex Gateway server IP¶

The PowerFlex Gateway provides a REST interface to PowerFlex.

Configure the Gateway server IP address by adding the following parameter:

san_ip = <PowerFlex GATEWAY IP>

PowerFlex Storage Pools¶

Multiple Storage Pools and Protection Domains can be listed for use by the virtual machines. The list should include every Protection Domain and Storage Pool pair that you would like Cinder to utilize.

To retrieve the available Storage Pools, use the command scli --query_all and search for available Storage Pools.

Configure the available Storage Pools by adding the following parameter:

powerflex_storage_pools = <Comma-separated list of protection domain:storage pool name>

PowerFlex user credentials¶

Block Storage requires a PowerFlex user with administrative privileges. Dell recommends creating a dedicated OpenStack user account that has an administrative user role.

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

Configure the user credentials by adding the following parameters:

san_login = <POWERFLEX_USER>
san_password = <POWERFLEX_PASSWD>

Oversubscription¶

Configure the oversubscription ratio by adding the following parameter under the separate section for PowerFlex:

powerflex_max_over_subscription_ratio = <OVER_SUBSCRIPTION_RATIO>

Oversubscription is calculated correctly by the Block Storage service only if the extra specification provisioning:type appears in the volume type regardless of the default provisioning type. Maximum oversubscription value supported for PowerFlex is 10.0.

Default provisioning type¶

If provisioning type settings are not specified in the volume type, the default value is set according to the san_thin_provision option in the configuration file. The default provisioning type will be thin if the option is not specified in the configuration file. To set the default provisioning type thick, set the san_thin_provision option to false in the configuration file, as follows:

san_thin_provision = false

The configuration file is usually located in /etc/cinder/cinder.conf. For a configuration example, see: cinder.conf.

Configuration example¶

cinder.conf example file

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

[DEFAULT]
enabled_backends = powerflex

[powerflex]
volume_driver = cinder.volume.drivers.dell_emc.powerflex.driver.PowerFlexDriver
volume_backend_name = powerflex
san_ip = GATEWAY_IP
powerflex_storage_pools = Domain1:Pool1,Domain2:Pool2
san_login = POWERFLEX_USER
san_password = POWERFLEX_PASSWD
san_thin_provision = false

Connector configuration¶

Before using attach/detach volume operations PowerFlex connector must be properly configured. On each node where PowerFlex SDC is installed do the following:

1. Create /opt/emc/scaleio/openstack/connector.conf if it does not exist.

   $ mkdir -p /opt/emc/scaleio/openstack
   $ touch /opt/emc/scaleio/openstack/connector.conf
   

2. For each PowerFlex section in the cinder.conf create the same section in the /opt/emc/scaleio/openstack/connector.conf and populate it with passwords. Example:

   [powerflex]
   san_password = POWERFLEX_PASSWD
   replicating_san_password = REPLICATION_SYSTEM_POWERFLEX_PASSWD # if applicable
   
   [powerflex-new]
   san_password = SIO2_PASSWD
   replicating_san_password = REPLICATION_SYSTEM_SIO2_PASSWD # if applicable
   

Configuration options¶

The PowerFlex driver supports these configuration options:

PowerFlex Protection Domain and Storage Pool¶

When multiple storage pools are specified in the Cinder configuration, users can specify which pool should be utilized by adding the pool_name Extra Spec to the volume type extra-specs and setting the value to the requested protection_domain:storage_pool.

$ openstack volume type create powerflex_type_1
$ openstack volume type set --property volume_backend_name=powerflex powerflex_type_1
$ openstack volume type set --property pool_name=Domain2:Pool2 powerflex_type_1

PowerFlex thin provisioning support¶

The Block Storage driver supports creation of thin-provisioned and thick-provisioned volumes. The provisioning type settings can be added as an extra specification of the volume type, as follows:

$ openstack volume type create powerflex_type_thick
$ openstack volume type set --property provisioning:type=thick powerflex_type_thick

PowerFlex QoS support¶

QoS support for the PowerFlex driver includes the ability to set the following capabilities:

maxIOPS

The QoS I/O rate limit. If not set, the I/O rate will be unlimited. The setting must be larger than 10.

maxIOPSperGB

The QoS I/O rate limit. The limit will be calculated by the specified value multiplied by the volume size. The setting must be larger than 10.

maxBWS

The QoS I/O bandwidth rate limit in KBs. If not set, the I/O bandwidth rate will be unlimited. The setting must be a multiple of 1024.

maxBWSperGB

The QoS I/O bandwidth rate limit in KBs. The limit will be calculated by the specified value multiplied by the volume size. The setting must be a multiple of 1024.

The QoS keys above must be created and associated with a volume type. For example:

$ openstack volume qos create qos-limit-iops --consumer back-end --property maxIOPS=5000
$ openstack volume type create powerflex_limit_iops
$ openstack volume qos associate qos-limit-iops powerflex_limit_iops

The driver always chooses the minimum between the QoS keys value and the relevant calculated value of maxIOPSperGB or maxBWSperGB.

Since the limits are per SDC, they will be applied after the volume is attached to an instance, and thus to a compute node/SDC.

PowerFlex compression support¶

Starting from version 3.0, PowerFlex supports volume compression. By default driver will create volumes without compression. In order to create a compressed volume, a volume type which enables compression support needs to be created first:

$ openstack volume type create powerflex_compressed
$ openstack volume type set --property provisioning:type=compressed powerflex_compressed

If a volume with this type is scheduled to a storage pool which doesn’t support compression, then thin provisioning will be used. See table below for details.

You can add property compression_support='<is> True' to volume type to limit volumes allocation only to data pools which supports compression.

$ openstack volume type set  --property compression_support='<is> True' powerflex_compressed

Prerequisites¶

• PowerFlex replication components must be installed on source and destination systems.

• Source and destination systems must have the same configuration for Protection Domains and their Storage Pools (i.e. names, zero padding, etc.).

• Source and destination systems must be paired and have at least one Replication Consistency Group created.

See Official PowerFlex documentation for instructions.

Configure replication¶

1. Enable replication in cinder.conf file.

   To enable replication feature for storage backend replication_device must be set as below:

   [DEFAULT]
   enabled_backends = powerflex
   
   [powerflex]
   volume_driver = cinder.volume.drivers.dell_emc.powerflex.driver.PowerFlexDriver
   volume_backend_name = powerflex
   san_ip = GATEWAY_IP
   powerflex_storage_pools = Domain1:Pool1,Domain2:Pool2
   san_login = POWERFLEX_USER
   san_password = POWERFLEX_PASSWD
   san_thin_provision = false
   replication_device = backend_id:powerflex_repl,
                        san_ip: REPLICATION_SYSTEM_GATEWAY_IP,
                        san_login: REPLICATION_SYSTEM_POWERFLEX_USER,
                        san_password: REPLICATION_SYSTEM_POWERFLEX_PASSWD
   

   • Only one replication device is supported for storage backend.

   • The following parameters are optional for replication device:

     • REST API port - powerflex_rest_server_port.

     • SSL certificate verification - driver_ssl_cert_verify and driver_ssl_cert_path.

   For more information see Configuration options.

2. Create volume type for volumes with replication enabled.

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

3. Set PowerFlex Replication Consistency Group name for volume type.

   $ openstack volume type set --property powerflex:replication_cg=<replication_cg name> \
       powerflex_replicated
   

4. Set Protection Domain and Storage Pool if multiple Protection Domains are specified.

   PowerFlex Replication Consistency Group is created between source and destination Protection Domains. If more than one Protection Domain is specified in cinder.conf you should set pool_name property for volume type with appropriate Protection Domain and Storage Pool. See PowerFlex Protection Domain and Storage Pool.

Failover host¶

In the event of a disaster, or where there is a required downtime the administrator can issue the failover host command:

$ cinder failover-host cinder_host@powerflex --backend_id powerflex_repl

After issuing Cinder failover-host command Cinder will switch to configured replication device, however to get existing instances to use this target and new paths to volumes it is necessary to first shelve Nova instances and then unshelve them, this will effectively restart the Nova instance and re-establish data paths between Nova instances and the volumes.

$ nova shelve <server>
$ nova unshelve [--availability-zone <availability_zone>] <server>

If the primary system becomes available, the administrator can initiate failback operation using --backend_id default:

$ cinder failover-host cinder_host@powerflex --backend_id default

Known limitations¶

• Migration between different backends is not supported.

• For migration from Medium Granularity (MG) to Fine Granularity (FG) storage pool zero padding must be enabled on the MG pool.

• For migration from MG to MG pool zero padding must be either enabled or disabled on both pools.

In the above cases host-assisted migration will be perfomed.

Migrate volume¶

Volume migration is performed by issuing the following command:

$ cinder migrate <volume> <host>

$ cinder reset-state --state available <volume>