The btrfsck command is a filesystem-check command like fsck, but it works with the btrfs file system.
First a little bit about btrfs. As the name implies, btrfs uses a B-tree data structure that is self-balancing and maintains sorted data, facilitating searches, sequential access, insertions, and deletions. It is also often referred to as the “better file system”. Oracle developed it and first used it about 15 years ago. By November 2013, it was declared adequately stable and began to be used by other distributions as well, and now its use is quite common.
Benefits of btrfs
The benefits of btrfs are impressive, although it’s still a work in progress and some concerns have kept it from playing a more dominant role on Linux systems. It keeps 2 copies of metadata on a volume, allowing for data recovery if and when the hard drive is damaged or suffers from bad sectors. It uses checksums and verifies them with each read. In addition, compared to ext4 volumes, btrfs does not require double the storage space to accommodate file versioning and history data.
Source:: Network World – Linux