Dell EqualLogic Back End Guide

This document describes how to configure OpenStack to use one or more Dell EqualLogic back ends. It also includes instructions on addressing volume size discrepancies between Dell EqualLogic devices and the OpenStack Block Storage service.

The following sections assume that:

When RHEL OpenStack Platform is deployed through the Director, all major Overcloud settings (in particular, the Block Storage service back end) must be defined and orchestrated through the Director as well. This ensures that the settings will persist through any further Overcloud updates. For more information about deploying OpenStack through the Director, see Director Installation and Usage.

The purpose of this document is to explain how to orchestrate your desired Dell EqualLogic back end configuration to the Overcloud’s Block Storage service. This document will not discuss the different deployment configurations possible with the back end. Rather, to learn more about the different available deployment configurations, see your device’s product documentation.

Once you are familiar with the resulting back end configuration you want to deploy (and its corresponding settings), refer to this document for instructions on how to orchestrate it through the Director.

RHEL OpenStack Platform includes all the drivers required for all Dell devices supported by the Block Storage service. In addition, the Director also has the puppet manifests, environment files, and Orchestration templates necessary for integrating the device as a back end to the Overcloud.

Configuring a single Dell device as a back end involves editing the default environment file and including it in the Overcloud deployment. This file is available locally on the Undercloud, and can be edited to suit your environment.

After editing this file, invoke it through the Director. Doing so ensures that it will persist through future Overcloud updates. The following sections describe this process in greater detail. In addition, the default environment file already contains enough information to call the necessary puppet manifests and Orchestration (Heat) templates that will configure the rest of the required Block Storage settings.

With a Director deployment, the easiest way to define a single Dell EqualLogic back end is through the integrated environment file. This file is located in the following path of the Undercloud node:

/usr/share/openstack-tripleo-heat-templates/environments/cinder-eqlx-config.yaml

Copy this file to a local path where you can edit and invoke it later. For example, to copy it to ~/templates/:

$ cp /usr/share/openstack-tripleo-heat-templates/environments/cinder-eqlx-config.yaml ~/templates/

Afterwards, open the copy (~/templates/cinder-eqlx-config.yaml) and edit it as you see fit. The following snippet displays the default contents of this file:

# A Heat environment file which can be used to enable a
# a Cinder  eqlx backen, configured via puppet
resource_registry:
  OS::TripleO::ControllerExtraConfigPre: ../puppet/extraconfig/pre_deploy/controller/cinder-eqlx.yaml # 1

parameter_defaults: # 2
  CinderEnableEqlxBackend: true # 3
  CinderEqlxBackendName: 'tripleo_eqlx'
  CinderEqlxSanIp: ''
  CinderEqlxSanLogin: ''
  CinderEqlxSanPassword: ''
  CinderEqlxSanThinProvision: true
  CinderEqlxGroupname: 'group-0'
  CinderEqlxPool: 'default'
  CinderEqlxChapLogin: ''
  CinderEqlxChapPassword: ''
  CinderEqlxUseChap: false

To define your Dell EqualLogic back end, edit the settings in the parameter_defaults section as you see fit. The following table explains each parameter, and also lists its corresponding /etc/cinder/cinder.conf setting.

The Director installation uses a non-root user to execute commands, which includes orchestrating the deployment of the Block Storage back end. In Creating a Director Installation User, we create a user named stack for this purpose. This user is configured with elevated privileges.

To deploy the lone back end configured in Section 3, “Define a Single Back End”, first log in as the stack user to the Undercloud. Then, deploy the back end (defined in the edited ~/templates/cinder-eqlx-config.yaml) by running the following:

$ openstack overcloud deploy --templates -e ~/templates/cinder-eqlx-config.yaml

Once the Director completes the orchestration, test the back end. See Section 5, “Test the Configured Back End” for instructions.

After deploying the back end, test whether you can successfully create volumes on it. Doing so will require loading the necessary environment variables first. These variables are defined in /home/stack/overcloudrc by default.

To load these variables, run the following command as the stack user:

$ source /home/stack/overcloudrc

You should now be logged in to the Controller node. From there, you can create a volume type, which can be used to specify the back end you want to use (in this case, the newly-defined back end in Section 3, “Define a Single Back End”). This is required in an OpenStack deployment where you have other back ends enabled (preferably, also through Director).

To create a volume type named delleql, run:

$ cinder type-create delleql

Next, map this volume type to the back end defined in Section 3, “Define a Single Back End”. Given the back end name tripleo_eqlx (as defined through the CinderEqlxBackendName parameter, in Section 3, “Define a Single Back End”), run:

$ cinder type-key delleql set volume_backend_name=tripleo_eqlx

You should now be able to create a 2GB volume on the newly defined back end by invoking its volume type. To do so, run:

$ cinder create --volume-type delleql 2

When reporting volume sizes, Dell EqualLogic (EQL) back ends also account for additional storage to be used for internal volume metadata. This size will be slightly larger than the volume size reported by the Block Storage services. However, the volume size reported by an EQL back end is the same one used by the Image service.

As a result, when creating an image-backed volume on an EQL back end, check the size of the image first. If the image was originally volume-backed, then EQL (and, by extension, the Image service) will be reporting a volume size slightly larger than what is reported by the Block Storage service.

If the image size reported by EQL is slightly larger, then you need to take the size discrepancy into consideration when creating volumes backed by this image.

+---------------------+--------------------------------------+
|       Property      |                Value                 |
+---------------------+--------------------------------------+
|     attachments     |                  []                  |
|  availability_zone  |                 nova                 |
|       bootable      |                false                 |
|      created_at     |      2014-12-19T03:57:47.730359      |
| display_description |                 None                 |
|     display_name    |                 vol1                 |
|      encrypted      |                False                 |
|          id         | 6bdace69-bd41-42fc-a63a-f834fb65a2e4 |
|       metadata      |                  {}                  |
|         size        |                  1                   |
|     snapshot_id     |                 None                 |
|     source_volid    |                 None                 |
|        status       |               creating               |
|     volume_type     |                 None                 |
+---------------------+--------------------------------------+

_______________________________ Volume Information ______...
Name: volume-6bdace69-bd41-42fc-a63a-f834fb65a2e4
Size: 1GB
VolReserve: 1.01GB
...

+---------------------+--------------------------------------+
|       Property      |                Value                 |
+---------------------+--------------------------------------+
|   container_format  |                 bare                 |
|     disk_format     |                 raw                  |
| display_description |                 None                 |
|          id         | 6bdace69-bd41-42fc-a63a-f834fb65a2e4 |
|       image_id      | c65f7eae-e2c1-44ba-8af1-e33695897559 |
|      image_name     |              image_vol1              |
|         size        |                  1                   |
|        status       |              uploading               |
|      updated_at     |      2014-12-19T03:57:48.000000      |
|     volume_type     |                 None                 |
+---------------------+--------------------------------------+

...+------------+-------------+------------------+------------+--------+
...| Name       | Disk Format | Container Format | Size       | Status |
...+------------+-------------+------------------+------------+--------+
...| image_vol1 | raw         | bare             | 1085276160 | active |
...+------------+-------------+------------------+------------+--------+

ERROR: Invalid input received: Size of specified image 2 is larger than volume size 1

+---------------------+--------------------------------------+
|       Property      |                Value                 |
+---------------------+--------------------------------------+
|     attachments     |                  []                  |
|  availability_zone  |                 nova                 |
|       bootable      |                false                 |
|      created_at     |      2014-12-19T04:54:07.036260      |
| display_description |                 None                 |
|     display_name    |                 vol2                 |
|      encrypted      |                False                 |
|          id         | fcf49715-094d-4bba-9f05-8b7fa6deffce |
|       image_id      | c65f7eae-e2c1-44ba-8af1-e33695897559 |
|       metadata      |                  {}                  |
|         size        |                  2                   |
|     snapshot_id     |                 None                 |
|     source_volid    |                 None                 |
|        status       |               creating               |
|     volume_type     |                 None                 |
+---------------------+--------------------------------------+