Chapter 19. Using the web console for configuring thin logical volumes

Thinly-provisioned logical volumes enable you to allocate more space for designated applications or servers than how much space logical volumes actually contain.

For details, see Thinly-provisioned logical volumes (thin volumes).

The following sections describe:

Prerequisites

  • The RHEL 8 web console has been installed.

    For details, see Installing the web console.

  • The cockpit-storaged package is installed on your system.
  • Physical drives or other types of storage devices from which you want to create volume groups.

19.1. Creating pools for thin logical volumes in the web console

Create a pool for thinly provisioned volumes.

Prerequisites

Procedure

  1. Log in to the RHEL 8 web console.
  2. Click Storage.
  3. Click the volume group in which you want to create thin volumes.
  4. Click Create new Logical Volume.
  5. In the Name field, enter a name for the new pool of thin volumes without spaces.
  6. In the Purpose drop down menu, select Pool for thinly provisioned volumes. This configuration enables you to create the thin volume.

    cockpit lv thin pool add

  7. Define the size of the pool of thin volumes. Consider:

    • How many thin volumes you will need in this pool?
    • What is the expected size of each thin volume?

    You do not have to use the whole space. If necessary, you can grow the pool later.

    cockpit lv thin pool size

  8. Click Create.

    The pool for thin volumes has been created and you can add thin volumes.

19.2. Creating thin logical volumes in the web console

Create a thin logical volume in the pool. The pool can include multiple thin volumes and each thin volume can be as large as the pool for thin volumes itself.

Important

Using thin volumes requires regular checkup of actual free physical space of the logical volume.

Prerequisites

Procedure

  1. Log in to the RHEL 8 web console.
  2. Click Storage.
  3. Click the volume group in which you want to create thin volumes.
  4. Click the desired pool.
  5. Click Create Thin Volume.

    cockpit lv pool tab

  6. In the Create Thin Volume dialog box, enter a name for the thin volume without spaces.
  7. Define the size of the thin volume.

    cockpit lv thin size

  8. Click Create.

At this stage, the thin logical volume has been created and you need to format it.

19.3. Formatting logical volumes in the web console

Logical volumes act as physical drives. To use them, you need to format them with a file system.

Warning

Formatting logical volumes will erase all data on the volume.

The file system you select determines the configuration parameters you can use for logical volumes. For example, some the XFS file system does not support shrinking volumes. For details, see Resizing logical volumes in the web console.

The following steps describe the procedure to format logical volumes.

Prerequisites

Procedure

  1. Log in to the RHEL web console.
  2. Click Storage.
  3. Click the volume group in which the logical volume is placed.
  4. Click the logical volume.
  5. Click on the Unrecognized Data tab.

    cockpit lv details

  6. Click Format.
  7. In the Erase drop down menu, select:

    • Don’t overwrite existing data — the RHEL web console rewrites only the disk header. Advantage of this option is speed of formatting.
    • Overwrite existing data with zeros — the RHEL web console rewrites the whole disk with zeros. This option is slower because the program have to go through the whole disk. Use this option if the disk includes any data and you need to overwrite it.
  8. In the Type drop down menu, select a file system:

    • XFS file system supports large logical volumes, switching physical drives online without outage, and growing an existing file system. Leave this file system selected if you do not have a different strong preference.

      XFS does not support reducing the size of a volume formatted with an XFS file system

    • ext4 file system supports:

      • Logical volumes
      • Switching physical drives online without outage
      • Growing a file system
      • Shrinking a file system

    You can also select a version with the LUKS (Linux Unified Key Setup) encryption, which allows you to encrypt the volume with a passphrase.

  9. In the Name field, enter the logical volume name.
  10. In the Mounting drop down menu, select Custom.

    The Default option does not ensure that the file system will be mounted on the next boot.

  11. In the Mount Point field, add the mount path.
  12. Select Mount at boot.

    cockpit lv format

  13. Click Format.

    Formatting can take several minutes depending on the volume size and which formatting options are selected.

    After the formatting has completed successfully, you can see the details of the formatted logical volume on the Filesystem tab.

    cockpit lv formatted

  14. To use the logical volume, click Mount.

At this point, the system can use mounted and formatted logical volume.