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Additionally, you can set a fixed size for the volume by selecting the `Fixed` option from the `Size policy` menu and entering a size for the volume group.
After you finish configuring the Btrfs volume settings, click `Save` to return to the main `Manual Partitioning` screen.
_Btrfs_ is a type of file system, but it has several features characteristic of a storage device. It is designed to make the file system tolerant of errors, and to facilitate the detection and repair of errors when they occur. It uses checksums to ensure the validity of data and metadata, and maintains snapshots of the file system that can be used for backup or repair.
Click the `+` button at the bottom of the list showing existing mount points. A new dialog window will open.
Configure other settings specific to the subvolume - its `Mount Point`, `Desired Capacity`, `File System`, and `Name`. Press `Update Settings` to apply any changes to the configuration.
Create Btrfs Subvolume
Creating a Btrfs Layout
Creating a Btrfs layout is somewhat similar to LVM (described in xref:Installing_Using_Anaconda.adoc#sect-installation-gui-manual-partitioning-lvm[Creating a Logical Volume Managament (LVM) Layout]) with slightly different terminology. A Btrfs _volume_ is the equivalent of an LVM volume group, and a Btrfs _subvolume_ is similar to a LVM logical volume. An important difference to note is how [application]*Anaconda* reports sizes for separate mount points: For LVM, the exact size of each logical volume is shown next to each mount point in the left pane, while with Btrfs, the total size of the entire volume is shown next to each subvolume.
Creating Btrfs Subvolumes and Volumes
Follow the procedure below to create Btrfs volumes and subvolumes:
For each mount point you create, review its settings and make sure that it is assigned to the correct volume, that it has sufficient capacity, and that it has a descriptive name so you can identify the subvolume later if you need to.
If you need to create more than one Btrfs volume, open the `Volume` drop-down menu and select the `Create a new volume group` option. A new dialog window will open, identical to the one described in the previous step. Again, select a name, storage devices, encryption settings, RAID level and size policy for the new volume, and click `Save`. The new volume will then become available in the `Volume Group` drop-down menu; you can then go through your existing mount points and change this setting to assign them to a different volume.
If you select a redundant RAID type (such as `RAID1 (Redundancy)`), the volume will take up twice its actual size on your disks. A 5 GB volume with RAID1 will take up 10 GB of space.
In the `Configure Volume` dialog, you can change the volume's name, its `RAID level` (see xref:Installing_Using_Anaconda.adoc#sect-installation-gui-manual-partitioning-filesystems[Device, File System and RAID Types] for information about available RAID types), and you can also specify which physical devices (disks) this volume should reside on. You can select one or more disks which will be used to hold this volume by holding down kbd:[Ctrl] and clicking each disk in the list.
In the new dialog window, specify a mount point for which you want to create a separate logical volume - for example, `/`. Optionally, specify a size for the volume using standard units such as MB or GB (for example, `50GB`). Then, click `Add mount point` to add the volume and return to the main partitioning screen.
In the `Volume` menu, you can see that the subvolume has been assigned to an automatically created volume, which is named after the {PRODUCT} variant you are installing (for example, `fedora-server00`. Click the `Modify` button under the drop-down menu to access the volume settings.
Repeat this procedure for any additional Btrfs subvolumes you want to create. Note that when creating additional subvolumes, a new volume is not automatically created each time; instead, any additional subvolumes are assigned to an existing volume.
Some partition types - notably the `/boot` and `/usr` directories and the BIOS Boot and EFI partitions - can not be placed on Btrfs subvolumes. Use standard physical volumes for them (or an LVM logical volume for `/usr`). See xref:Installing_Using_Anaconda.adoc#sect-installation-gui-manual-partitioning-recommended[Recommended Partitioning Scheme] for more information.
The Manual Partitioning screen