Dell EMC VxFlex OS (ScaleIO) Storage driver


Dell EMC VxFlex OS (formerly named Dell EMC ScaleIO) is a software-only solution that uses existing servers local disks and LAN to create a virtual SAN that has all of the benefits of external storage, but at a fraction of the cost and complexity. Using the driver, Block Storage hosts can connect to a VxFlex OS Storage cluster.

The Dell EMC VxFlex OS Cinder driver is designed and tested to work with both VxFlex OS and with ScaleIO. The configuration options are identical for both VxFlex OS and ScaleIO.

Official VxFlex OS documentation

To find the VxFlex OS documentation:

  1. Go to the VxFlex OS product documentation page.

  2. From the left-side panel, select the relevant VxFlex OS version.

Supported VxFlex OS and ScaleIO Versions

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

  • ScaleIO 2.0.x

  • ScaleIO 2.5.x

  • VxFlex OS 2.6.x

  • VxFlex OS 3.0.x

  • VxFlex OS 3.5.x

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

Deployment prerequisites

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

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


Ubuntu users must follow the specific instructions in the VxFlex OS Deployment Guide for Ubuntu environments. See the Deploying on Ubuntu Servers section in VxFlex OS Deployment Guide. See Official VxFlex OS documentation.

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

VxFlex OS Block Storage driver configuration

This section explains how to configure and connect the block storage nodes to a VxFlex OS storage cluster.

Edit the cinder.conf file by adding the configuration below under a new section (for example, [vxflexos]) and change the enable_backends setting (in the [DEFAULT] section) to include this new back end. The configuration file is usually located at /etc/cinder/cinder.conf.

For a configuration example, refer to the example cinder.conf.

VxFlex OS driver name

Configure the driver name by adding the following parameter:

volume_driver = cinder.volume.drivers.dell_emc.vxflexos.driver.VxFlexOSDriver

VxFlex OS Gateway server IP

The VxFlex OS Gateway provides a REST interface to VxFlex OS.

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

san_ip = <VxFlex OS GATEWAY IP>

VxFlex OS 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:

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

VxFlex OS user credentials

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

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

Configure the user credentials by adding the following parameters:

san_login = <SIO_USER>
san_password = <SIO_PASSWD>


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

vxflexos_max_over_subscription_ratio = <OVER_SUBSCRIPTION_RATIO>


The default value for vxflexos_max_over_subscription_ratio is 10.0.

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 VxFlex OS 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:

enabled_backends = vxflexos

volume_driver = cinder.volume.drivers.dell_emc.vxflexos.driver.VxFlexOSDriver
volume_backend_name = vxflexos
san_ip = GATEWAY_IP
vxflexos_storage_pools = Domain1:Pool1,Domain2:Pool2
san_login = SIO_USER
san_password = SIO_PASSWD
san_thin_provision = false

Connector configuration

Before using attach/detach volume operations VxFlex OS connector must be properly configured. On each node where VxFlex OS 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 VxFlex OS section in the cinder.conf create the same section in the /opt/emc/scaleio/openstack/connector.conf and populate it with passwords. Example:

    san_password = SIO_PASSWD
    replicating_san_password = REPLICATION_SYSTEM_SIO_PASSWD # if applicable
    san_password = SIO2_PASSWD
    replicating_san_password = REPLICATION_SYSTEM_SIO2_PASSWD # if applicable

Configuration options

The VxFlex OS driver supports these configuration options:

Description of VxFlex OS configuration options

Configuration option = Default value


vxflexos_allow_migration_during_rebuild = False

(Boolean) Allow volume migration during rebuild.

vxflexos_allow_non_padded_volumes = False

(Boolean) Allow volumes to be created in Storage Pools when zero padding is disabled. This option should not be enabled if multiple tenants will utilize volumes from a shared Storage Pool.

vxflexos_max_over_subscription_ratio = 10.0

(Float) max_over_subscription_ratio setting for the driver. Maximum value allowed is 10.0.

vxflexos_rest_server_port = 443

(Port(min=0, max=65535)) Gateway REST server port.

vxflexos_round_volume_capacity = True

(Boolean) Round volume sizes up to 8GB boundaries. VxFlex OS/ScaleIO requires volumes to be sized in multiples of 8GB. If set to False, volume creation will fail for volumes not sized properly

vxflexos_server_api_version = None

(String) VxFlex OS/ScaleIO API version. This value should be left as the default value unless otherwise instructed by technical support.

vxflexos_storage_pools = None

(String) Storage Pools. Comma separated list of storage pools used to provide volumes. Each pool should be specified as a protection_domain_name:storage_pool_name value

vxflexos_unmap_volume_before_deletion = False

(Boolean) Unmap volumes before deletion.

sio_allow_non_padded_volumes = False

(Boolean) renamed to vxflexos_allow_non_padded_volumes. DEPRECATED

sio_max_over_subscription_ratio = 10.0

(Float) renamed to vxflexos_max_over_subscription_ratio. DEPRECATED

sio_rest_server_port = 443

(Port(min=0, max=65535)) renamed to vxflexos_rest_server_port. DEPRECATED

sio_round_volume_capacity = True

(Boolean) renamed to vxflexos_round_volume_capacity. DEPRECATED

sio_server_api_version = None

(String) renamed to vxflexos_server_api_version. DEPRECATED

sio_server_certificate_path = None

(String) Deprecated, use driver_ssl_cert_path instead. DEPRECATED

sio_storage_pools = None

(String) renamed to vxflexos_storage_pools. DEPRECATED

sio_unmap_volume_before_deletion = False

(Boolean) renamed to vxflexos_unmap_volume_before_deletion. DEPRECATED

sio_verify_server_certificate = False

(Boolean) Deprecated, use driver_ssl_cert_verify instead. DEPRECATED

Volume Types

Volume types can be used to specify characteristics of volumes allocated via the VxFlex OS Driver. These characteristics are defined as Extra Specs within Volume Types.

VxFlex OS 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 vxflexos_type_1
$ openstack volume type set --property volume_backend_name=vxflexos vxflexos_type_1
$ openstack volume type set --property pool_name=Domain2:Pool2 vxflexos_type_1

VxFlex OS 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 vxflexos_type_thick
$ openstack volume type set --property provisioning:type=thick vxflexos_type_thick

VxFlex OS QoS support

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


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


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.


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.


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 vxflexos_limit_iops
$ openstack volume qos associate qos-limit-iops vxflexos_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.

VxFlex OS compression support

Starting from version 3.0, VxFlex OS 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 vxflexos_compressed
$ openstack volume type set --property provisioning:type=compressed vxflexos_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.


storage pool supports compression

yes (VxFlex 3.0 FG pool)

no (other pools)


thin with compression








not set




VxFlex 3.0 Fine Granularity storage pools don’t support thick provisioned volumes.

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' vxflexos_compressed

VxFlex OS replication support

Starting from version 3.5, VxFlex OS supports volume replication.


  • VxFlex OS 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 VxFlex OS 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:

    enabled_backends = vxflexos
    volume_driver = cinder.volume.drivers.dell_emc.vxflexos.driver.VxFlexOSDriver
    volume_backend_name = vxflexos
    san_ip = GATEWAY_IP
    vxflexos_storage_pools = Domain1:Pool1,Domain2:Pool2
    san_login = SIO_USER
    san_password = SIO_PASSWD
    san_thin_provision = false
    replication_device = backend_id:vxflexos_repl,
                         san_ip: REPLICATION_SYSTEM_GATEWAY_IP,
                         san_login: REPLICATION_SYSTEM_SIO_USER,
                         san_password: REPLICATION_SYSTEM_SIO_PASSWD
    • Only one replication device is supported for storage backend.

    • The following parameters are optional for replication device:

      • REST API port - vxflexos_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 vxflexos_replicated
    $ openstack volume type set --property replication_enabled='<is> True' vxflexos_replicated
  3. Set VxFlex OS Replication Consistency Group name for volume type.

    $ openstack volume type set --property vxflexos:replication_cg=<replication_cg name> \
  4. Set Protection Domain and Storage Pool if multiple Protection Domains are specified.

    VxFlex OS 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 VxFlex OS 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@vxflexos --backend_id vxflexos_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@vxflexos --backend_id default

VxFlex OS storage-assisted volume migration

Starting from version 3.0, VxFlex OS supports storage-assisted volume migration.

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>


Volume migration has a timeout of 3600 seconds (1 hour). It is done to prevent from endless waiting for migration to complete if something unexpected happened. If volume still is in migration after timeout has expired, volume status will be changed to maintenance to prevent future operations with this volume. The corresponding warning will be logged.

In this situation the status of the volume should be checked on the storage side. If volume migration succeeded, its status can be changed manually:

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

Using VxFlex OS Storage with a containerized overcloud

  1. Create a file with below contents:

        - /opt/emc/scaleio:/opt/emc/scaleio
        - /opt/emc/scaleio:/opt/emc/scaleio
        - /opt/emc/scaleio:/opt/emc/scaleio

    Name it whatever you like, e.g. vxflexos_volumes.yml.

  2. Use -e to include this customization file to deploy command.

  3. Install the Storage Data Client (SDC) on all nodes after deploying the overcloud.