3.4 Installing a System With a Btrfs root File System

Oracle Linux 7 uses XFS as the default file system. Follow these steps to install a system with a Btrfs root file system:

  1. Begin the installation by booting the system from the installation media.

  2. On the Installation Summary screen, select Installation Destination. The Installation Destination screen is displayed.

  3. Select the local disks and add any Specialized & Network disks you want to use for the installation.

  4. (Optional) Select Encrypt my data.

    The encryption is applied to the block devices that contain the btrfs subvolumes and file systems.

  5. Select I will configure partitioning and click Done. The Manual Partitioning screen is displayed.

  6. (Optional) Free disk space by removing existing partitions.

    On the left-hand side, select a mount point and click the - button to remove it. Changes to partitioning are not applied until you click Begin Installation on the Installation Summary screen.

  7. Create the mount points.

    From the partitioning scheme list, select BTRFS.

    To create the default mount points automatically, click Click here to create them automatically. By default, automatic partitioning creates the following layout:

    • A 500 MiB, or 1 GiB if you are running Oracle Linux 7 Update 3 or later, partition for an XFS file system that contains /boot.

    • A 200 MiB EFI system partition mounted at /boot/efi (UEFI-based systems only).

    • A btrfs subvolume that contains the root file system (/).

    • A btrfs subvolume that contains the /home file system.

    • A swap partition.

    To create mount points manually, click the + button. As a minimum, create mount points for /, /boot, /home, and swap. The swap and /boot partitions cannot be configured as btrfs file systems.

    Figure 3.2 shows the results after automatic btrfs partitioning.

    Figure 3.2 Mount Points After Automatic Partitioning

  8. Configure the btrfs root file system.

    Select the / mount point and click Modify. The Configure Volume window is displayed, as shown in Figure 3.3.

    Specify a name for the volume, select the disks to use, the RAID level, and the size policy.

    If you select the Encrypt check box, this enables encryption for the block device that contains the root file system because btrfs does not support encryption at the file-system level. The same applies, if you enable encryption on a different btrfs subvolume such as /home.

  9. Click Save. The Configure Volume screen is closed. Click Update Settings to refresh the screen with your configuration changes.

  10. Click Done. If you enabled encryption, you are prompted to enter an encryption passphrase.

  11. Proceed with the rest of the installation.