Definition
Plain language
A high-performance Linux filesystem that supports advanced features like reflinks.
As stated in the literature
A 64-bit journaling filesystem for Linux supporting block-level reference counting (reflinks), used as the underlying storage layer for DeltaBox's DeltaFS.
Why it matters: Its block-level features enable storage techniques like fast snapshots and deduplicated backups that simpler filesystems can't support.
For example, on an XFS volume, a snapshot system can clone a 100GB virtual disk in milliseconds via reflinks instead of copying every block.
Heard on the show
“… And underneath the whole thing they use XFS with reflinks turned on, which means when a file does get copied up from a read-only layer because …”Episode 068 — The OS Trick That Makes Tree Search Practical for Coding Agents