B-trees, Shadowing, and Clones Ohad Rodeh IBM Haifa Research Labs B-trees are used by many file-systems to represent files and directories. They provide guarantied logarithmic time key-search, insert, and remove. File systems like WAFL and ZFS use shadow- ing, or copy-on-write, to implement snapshots, crash-recovery, write-batching and RAID. Serious difficulties arise when trying to use b-trees and s