19.2 About the Btrfs File System

The btrfs file system is designed to meet the expanding scalability requirements of large storage subsystems. As the btrfs file system uses B-trees in its implementation, its name derives from the name of those data structures, although it is not a true acronym. A B-tree is a tree-like data structure that enables file systems and databases to efficiently access and update large blocks of data no matter how large the tree grows.

The btrfs file system provides the following important features:

  • Copy-on-write functionality allows you to create both readable and writable snapshots, and to roll back a file system to a previous state, even after you have converted it from an ext3 or ext4 file system.

  • Checksum functionality ensures data integrity.

  • Transparent compression saves disk space.

  • Transparent defragmentation improves performance.

  • Integrated logical volume management allows you to implement RAID 0, RAID 1, or RAID 10 configurations, and to dynamically add and remove storage capacity.

Starting with Oracle Linux 6 Update 3, the UEK Boot ISO (which boots the Unbreakable Enterprise Kernel as the installation kernel) allows you to configure a btrfs root file system. Prior to Oracle Linux 6 Update 3, you could not create a btrfs root file system during installation. For more information, see Section 19.13, “Installing a Btrfs root File System”.


Configuring a swap file on a btrfs file system is not supported.

You can find more information about the btrfs file system at https://btrfs.wiki.kernel.org/index.php/Main_Page.