OpenStack Block Storage (Cinder)
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Dell EMC ScaleIO Block Storage driver

Overview

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 ScaleIO Storage cluster.

Official ScaleIO documentation

To find the ScaleIO documentation:

  1. Go to the ScaleIO product documentation page.
  2. From the left-side panel, select the relevant ScaleIO version.

Supported ScaleIO Versions

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

  • ScaleIO 2.0.x
  • ScaleIO 2.5.x

Please consult the scale_io_docs to determine supported operating systems for each version of ScaleIO.

Deployment prerequisites

  • ScaleIO Gateway must be installed and accessible in the network. For installation steps, refer to the Preparing the installation Manager and the Gateway section in ScaleIO Deployment Guide. See scale_io_docs.
  • ScaleIO Data Client (SDC) must be installed on all OpenStack nodes.

Note

Ubuntu users must follow the specific instructions in the ScaleIO Deployment Guide for Ubuntu environments. See the Deploying on Ubuntu Servers section in ScaleIO Deployment Guide. See scale_io_docs.

Supported operations

  • Create, delete, clone, attach, detach, manage, and unmanage volumes
  • Create, delete, manage, and unmanage volume snapshots
  • Create a volume from 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

ScaleIO Block Storage driver configuration

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

Edit the cinder.conf file by adding the configuration below under a new section (for example, [scaleio]) 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 <cg_configuration_example_emc> .

ScaleIO driver name

Configure the driver name by adding the following parameter:

ScaleIO Gateway server IP

The ScaleIO Gateway provides a REST interface to ScaleIO.

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

ScaleIO 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:

ScaleIO user credentials

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

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

Configure the user credentials by adding the following parameters:

Oversubscription

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

Note

The default value for sio_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 ScaleIO 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:

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

Configuration example

cinder.conf example file

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

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:

Configuration options

The ScaleIO driver supports these configuration options:

Volume Types

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

ScaleIO 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 Extra Spec to the volume type extra-specs and setting the value to the requested protection_domain:storage_pool.

$ openstack volume type create sio_type_1
$ openstack volume type set --property volume_backend_name=scaleio sio_type_1
$ openstack volume type set --property pool=Domain2:Pool2 sio_type_1

ScaleIO 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 sio_type_thick
$ openstack volume type set --property provisioning:type=thick sio_type_thick

ScaleIO QoS support

QoS support for the ScaleIO 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 sio_limit_iops
$ openstack volume qos associate qos-limit-iops sio_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.

Using ScaleIO Storage with a containerized overcloud

When using a containerized overcloud, such as one deployed via TripleO or RedHat Openstack version 12 and above, there is an additional step that must be performed.

Before deploying the overcloud

After ensuring that the ScaleIO Data Client (SDC) is installed on all nodes and before deploying the overcloud, modify the TripleO Heat Template for the nova-compute and cinder-volume containers to add volume mappings for directories containing the SDC components. These files can normally be found at /usr/share/openstack-tripleo-heat-templates/docker/services/nova-compute.yaml and /usr/share/openstack-tripleo-heat-templates/docker/services/cinder-volume.yaml

Two lines need to be inserted into the list of mapped volumes in each container.

The changes to the two heat templates are identical, as an example the original nova-compute file should have section that resembles the following:

After modifying the nova-compute file, the section should resemble:

Once the nova-compute file is modified, make an identical change to the cinder-volume file.

Deploy the overcloud

Once the above changes have been made, deploy the overcloud as usual.