Install and configure a storage node¶

This section describes how to install and configure storage nodes for the Block Storage service. For simplicity, this configuration references one storage node with an empty local block storage device. The instructions use /dev/sdb, but you can substitute a different value for your particular node.

The service provisions logical volumes on this device using the LVM driver and provides them to instances via iSCSI transport. You can follow these instructions with minor modifications to horizontally scale your environment with additional storage nodes.

Prerequisites¶

Before you install and configure the Block Storage service on the storage node, you must prepare the storage device.

Note

Perform these steps on the storage node.

Install the supporting utility packages:
- Install the LVM packages:
```
# yum install lvm2
```
- Start the LVM metadata service and configure it to start when the system boots:
```
# systemctl enable lvm2-lvmetad.service
# systemctl start lvm2-lvmetad.service
```
Note

Some distributions include LVM by default.

Create the LVM physical volume /dev/sdb:

# pvcreate /dev/sdb

Physical volume "/dev/sdb" successfully created

Create the LVM volume group cinder-volumes:
```
# vgcreate cinder-volumes /dev/sdb

Volume group "cinder-volumes" successfully created
```
The Block Storage service creates logical volumes in this volume group.
Only instances can access Block Storage volumes. However, the underlying operating system manages the devices associated with the volumes. By default, the LVM volume scanning tool scans the /dev directory for block storage devices that contain volumes. If projects use LVM on their volumes, the scanning tool detects these volumes and attempts to cache them which can cause a variety of problems with both the underlying operating system and project volumes. You must reconfigure LVM to scan only the devices that contain the cinder-volumes volume group. Edit the /etc/lvm/lvm.conf file and complete the following actions:
- In the devices section, add a filter that accepts the /dev/sdb device and rejects all other devices:
```
devices {
...
filter = [ "a/sdb/", "r/.*/"]
```
  Each item in the filter array begins with a for accept or r for reject and includes a regular expression for the device name. The array must end with r/.*/ to reject any remaining devices. You can use the vgs -vvvv command to test filters.
  Warning
  
  If your storage nodes use LVM on the operating system disk, you must also add the associated device to the filter. For example, if the /dev/sda device contains the operating system:
  filter = [ "a/sda/", "a/sdb/", "r/.*/"]
  Similarly, if your compute nodes use LVM on the operating system disk, you must also modify the filter in the /etc/lvm/lvm.conf file on those nodes to include only the operating system disk. For example, if the /dev/sda device contains the operating system:
  filter = [ "a/sda/", "r/.*/"]

Install and configure components¶

Install the packages:

# yum install openstack-cinder targetcli python-keystone

Edit the /etc/cinder/cinder.conf file and complete the following actions:
- In the [database] section, configure database access:
```
[database]
...
connection = mysql+pymysql://cinder:CINDER_DBPASS@controller/cinder
```
  Replace CINDER_DBPASS with the password you chose for the Block Storage database.
- In the [DEFAULT] section, configure RabbitMQ message queue access:
```
[DEFAULT]
...
transport_url = rabbit://openstack:RABBIT_PASS@controller
```
  Replace RABBIT_PASS with the password you chose for the openstack account in RabbitMQ.
- In the [DEFAULT] and [keystone_authtoken] sections, configure Identity service access:
```
[DEFAULT]
...
auth_strategy = keystone

[keystone_authtoken]
...
auth_uri = http://controller:5000
auth_url = http://controller:35357
memcached_servers = controller:11211
auth_type = password
project_domain_name = Default
user_domain_name = Default
project_name = service
username = cinder
password = CINDER_PASS
```
  Replace CINDER_PASS with the password you chose for the cinder user in the Identity service.
  
  Note
  
  Comment out or remove any other options in the [keystone_authtoken] section.
- In the [DEFAULT] section, configure the my_ip option:
```
[DEFAULT]
...
my_ip = MANAGEMENT_INTERFACE_IP_ADDRESS
```
  Replace MANAGEMENT_INTERFACE_IP_ADDRESS with the IP address of the management network interface on your storage node, typically 10.0.0.41 for the first node in the example architecture.
- In the [lvm] section, configure the LVM back end with the LVM driver, cinder-volumes volume group, iSCSI protocol, and appropriate iSCSI service. If the [lvm] section does not exist, create it:
```
[lvm]
volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver
volume_group = cinder-volumes
iscsi_protocol = iscsi
iscsi_helper = lioadm
```
- In the [DEFAULT] section, enable the LVM back end:
```
[DEFAULT]
...
enabled_backends = lvm
```
  Note
  
  Back-end names are arbitrary. As an example, this guide uses the name of the driver as the name of the back end.
- In the [DEFAULT] section, configure the location of the Image service API:
```
[DEFAULT]
...
glance_api_servers = http://controller:9292
```
- In the [oslo_concurrency] section, configure the lock path:
```
[oslo_concurrency]
...
lock_path = /var/lib/cinder/tmp
```

Finalize installation¶

Start the Block Storage volume service including its dependencies and configure them to start when the system boots:

# systemctl enable openstack-cinder-volume.service target.service
# systemctl start openstack-cinder-volume.service target.service