Chapter 8. Configuring LVM on shared storage

Procedure

1. In the lvm.conf file, check if the system.devices file is enabled:

   use_devicesfile=1

2. Exclude the devices in question from the host’s devices file:

   $ lvmdevices --deldev <device>

3. Optional: You can further protect LVM devices:

   1. Set the LVM system ID feature in both the host and the VM in the lvm.conf file:

      system_id_source = "uname"

   2. Set the VG’s system ID to match the VM system ID. This ensures that only the guest VM is capable of activating the VG:

      $ vgchange --systemid <VM_system_id> <VM_vg_name>

Procedure

1. In the lvm.conf file, check if the system.devices file is enabled:

   use_devicesfile=1

2. Exclude the devices in question from the host’s devices file:

   $ lvmdevices --deldev <device>

3. Set the LVM system ID feature in the lvm.conf file:

   system_id_source = "uname"

4. Set the VG’s system ID to match the system ID of the machine using this VG:

   $ vgchange --systemid <system_id> <vg_name>

Procedure

1. In the lvm.conf file, check if the system.devices file is enabled:

   use_devicesfile=1

2. Include the devices in question in the host’s devices file:

   $ lvmdevices --adddev <device>

3. Set the LVM system ID feature in all machines in the lvm.conf file:

   system_id_source = "uname"

Procedure

1. In the lvm.conf file, check if the system.devices file is enabled:

   use_devicesfile=1

2. For each machine that will use the shared LUN, add the LUN in the machines devices file:

   $ lvmdevices --adddev <device>

3. Configure the lvm.conf file to use the lvmlockd daemon on all machines:

   use_lvmlockd=1

4. Start the lvmlockd daemon file on all machines.
5. Start a lock manager to use with lvmlockd, such as dlm or sanlock on all machines.
6. Create a new shared VG using the command vgcreate --shared.
7. Start and stop access to existing shared VGs using the commands vgchange --lockstart and vgchange --lockstop on all machines.

Procedure

1. Create a playbook file, for example ~/playbook.yml, with the following content:

   ---
   - name: Manage local storage
     hosts: managed-node-01.example.com
     become: true
     tasks:
       - name: Create shared LVM device
         ansible.builtin.include_role:
           name: rhel-system-roles.storage
         vars:
           storage_pools:
             - name: vg1
               disks: /dev/vdb
               type: lvm
               shared: true
               state: present
               volumes:
                 - name: lv1
                   size: 4g
                   mount_point: /opt/test1
           storage_safe_mode: false
           storage_use_partitions: true

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.storage/README.md file on the control node.

2. Validate the playbook syntax:

   $ ansible-playbook --syntax-check ~/playbook.yml

   Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

3. Run the playbook:

   $ ansible-playbook ~/playbook.yml