btrfs

IMAGE GALLERY (1)

B-tree FS

• copy-on-write COW principle¹
  • Underlying mechanism for snapshots as provided by LVM
  • Weak form of incremental backup
  • copy-on-write usually refers to the first technique. CoW does two data writes compared to ROW’s one; it is difficult to implement efficiently and thus used infrequently.
  • The qcow2 (QEMU copy on write) disk image format uses the copy-on-write technique to reduce disk image size.
• In computer storage, logical volume management or LVM provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes to store volumes
• Btrfs is intended to address the lack of pooling, snapshots, checksums, and integral multi-device spanning in Linux file systems.
• btrfs status²
• Snapshot
  • A snapshot is simply a subvolume that shares its data (and metadata) with some other subvolume, using Btrfs’s COW capabilities.

Footnotes