Dell EMC Unity driver¶

Prerequisites¶

Supported operations¶

• Create, delete, attach, and detach volumes.
• Create, list, and delete volume snapshots.
• Create a volume from a snapshot.
• Copy an image to a volume.
• Create an image from a volume.
• Clone a volume.
• Extend a volume.
• Migrate a volume.
• Get volume statistics.
• Efficient non-disruptive volume backup.

Driver configuration¶

1. Install storops from pypi:

   # pip install storops
   

2. Add the following content into /etc/cinder/cinder.conf:

   [DEFAULT]
   enabled_backends = unity
   
   [unity]
   # Storage protocol
   storage_protocol = iSCSI
   # Unisphere IP
   san_ip = <SAN IP>
   # Unisphere username and password
   san_login = <SAN LOGIN>
   san_password = <SAN PASSWORD>
   # Volume driver name
   volume_driver = cinder.volume.drivers.dell_emc.unity.Driver
   # backend's name
   volume_backend_name = Storage_ISCSI_01
   

   Note

   These are minimal options for Unity driver, for more options, see Driver options.

1. Install sysfsutils, sg3-utils and multipath-tools:

   # apt-get install multipath-tools sg3-utils sysfsutils
   

2. (Required for FC driver in case Auto-zoning Support is disabled) Zone the FC ports of Compute nodes with Unity FC target ports.

3. Enable Unity storage optimized multipath configuration:

   Add the following content into /etc/multipath.conf

   blacklist {
       # Skip the files uner /dev that are definitely not FC/iSCSI devices
       # Different system may need different customization
       devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
       devnode "^hd[a-z][0-9]*"
       devnode "^cciss!c[0-9]d[0-9]*[p[0-9]*]"
   
       # Skip LUNZ device from VNX/Unity
       device {
           vendor "DGC"
           product "LUNZ"
       }
   }
   
   defaults {
       user_friendly_names no
       flush_on_last_del yes
   }
   
   devices {
       # Device attributed for EMC CLARiiON and VNX/Unity series ALUA
       device {
           vendor "DGC"
           product ".*"
           product_blacklist "LUNZ"
           path_grouping_policy group_by_prio
           path_selector "round-robin 0"
           path_checker emc_clariion
           features "0"
           no_path_retry 12
           hardware_handler "1 alua"
           prio alua
           failback immediate
       }
   }
   

4. Restart the multipath service:

   # service multipath-tools restart
   

5. Enable multipath for image transfer in /etc/cinder/cinder.conf.

   use_multipath_for_image_xfer = True
   

   Restart the cinder-volume service to load the change.

6. Enable multipath for volume attache/detach in /etc/nova/nova.conf.

   [libvirt]
   ...
   volume_use_multipath = True
   ...
   

7. Restart the nova-compute service.

Driver options¶

unity_io_ports = spa_eth2, spb_eth2, *_eth3

unity_io_ports = spa_iom_0_fc0, spb_iom_0_fc0, *_iom_0_fc1

$ uemcli /net/port/eth show -output csv
...
"spa_eth2","SP A Ethernet Port 2","spa","file, net, iscsi", ...
"spb_eth2","SP B Ethernet Port 2","spb","file, net, iscsi", ...
...

$ uemcli /net/port/fc show -output csv
...
"spa_iom_0_fc0","SP A I/O Module 0 FC Port 0","spa", ...
"spb_iom_0_fc0","SP B I/O Module 0 FC Port 0","spb", ...
...

Live migration integration¶

It is suggested to have multipath configured on Compute nodes for robust data access in VM instances live migration scenario. Once user_friendly_names no is set in defaults section of /etc/multipath.conf, Compute nodes will use the WWID as the alias for the multipath devices.

To enable multipath in live migration:

1. Set multipath in /etc/nova/nova.conf:

   [libvirt]
   ...
   volume_use_multipath = True
   ...
   

   Restart nova-compute service.

2. Set user_friendly_names no in /etc/multipath.conf

   ...
   defaults {
       user_friendly_names no
   }
   ...
   

3. Restart the multipath-tools service.

Thin and thick provisioning¶

Only thin volume provisioning is supported in Unity volume driver.

QoS support¶

Unity driver supports maxBWS and maxIOPS specs for the back-end consumer type. maxBWS represents the Maximum IO/S absolute limit, maxIOPS represents the Maximum Bandwidth (KBPS) absolute limit on the Unity respectively.

Auto-zoning support¶

Unity volume driver supports auto-zoning, and share the same configuration guide for other vendors. Refer to Fibre Channel Zone Manager for detailed configuration steps.

Solution for LUNZ device¶

The EMC host team also found LUNZ on all of the hosts, EMC best practice is to present a LUN with HLU 0 to clear any LUNZ devices as they can cause issues on the host. See KB LUNZ Device.

To workaround this issue, Unity driver creates a Dummy LUN (if not present), and adds it to each host to occupy the HLU 0 during volume attachment.

Efficient non-disruptive volume backup¶

The default implementation in Block Storage for non-disruptive volume backup is not efficient since a cloned volume will be created during backup.

An effective approach to backups is to create a snapshot for the volume and connect this snapshot to the Block Storage host for volume backup.

SSL support¶

Admin is able to enable the SSL verification for any communication against Unity REST API.

By default, the SSL verification is disabled, user can enable it by following steps:

1. Setup the Unity array certificate and import it to the Unity, see section Storage system certificate of Security Configuration Guide.
2. Import the CA certficate to the Cinder nodes on which the driver is running.
3. Enable the changes on cinder nodes and restart the cinder services.

[unity]
...
driver_ssl_cert_verify = True
driver_ssl_cert_path = <path to the CA>
...

If driver_ssl_cert_path is omitted, the system default CA will be used for CA verification.

Force detach volume from all hosts¶

The user could use os-force_detach action to detach a volume from all its attached hosts. For more detail, please refer to https://developer.openstack.org/api-ref/block-storage/v2/?expanded=force-detach-volume-detail#force-detach-volume

Troubleshooting¶

To troubleshoot a failure in OpenStack deployment, the best way is to enable verbose and debug log, at the same time, leverage the build-in Return request ID to caller to track specific Block Storage command logs.

1. Enable verbose log, set following in /etc/cinder/cinder.conf and restart all Block Storage services:

   [DEFAULT]
   
   ...
   
   debug = True
   verbose = True
   
   ...
   

   If other projects (usually Compute) are also involved, set debug and verbose to True.

2. use --debug to trigger any problematic Block Storage operation:

   # cinder --debug create --name unity_vol1 100
   

   You will see the request ID from the console, for example:

   DEBUG:keystoneauth:REQ: curl -g -i -X POST
   http://192.168.1.9:8776/v2/e50d22bdb5a34078a8bfe7be89324078/volumes -H
   "User-Agent: python-cinderclient" -H "Content-Type: application/json" -H
   "Accept: application/json" -H "X-Auth-Token:
   {SHA1}bf4a85ad64302b67a39ad7c6f695a9630f39ab0e" -d '{"volume": {"status":
   "creating", "user_id": null, "name": "unity_vol1", "imageRef": null,
   "availability_zone": null, "description": null, "multiattach": false,
   "attach_status": "detached", "volume_type": null, "metadata": {},
   "consistencygroup_id": null, "source_volid": null, "snapshot_id": null,
   "project_id": null, "source_replica": null, "size": 10}}'
   DEBUG:keystoneauth:RESP: [202] X-Compute-Request-Id:
   req-3a459e0e-871a-49f9-9796-b63cc48b5015 Content-Type: application/json
   Content-Length: 804 X-Openstack-Request-Id:
   req-3a459e0e-871a-49f9-9796-b63cc48b5015 Date: Mon, 12 Dec 2016 09:31:44 GMT
   Connection: keep-alive
   

3. Use commands like grep, awk to find the error related to the Block Storage operations.

   # grep "req-3a459e0e-871a-49f9-9796-b63cc48b5015" cinder-volume.log