What is BetrFS? The Bε-tree File System, or BetrFS, is an in-kernel file system that uses Bε trees to organize on-disk storage. Bε trees are a write-optimized dictionary, and offer the same asymptotic behavior for sequential I/O and point queries as a B-tree. The advantage of a B ε tree is that it can also ingest small, random writes 1-2 orders of magnitude faster than B-trees and other standard o