Generalized file system dependencies

Reliable storage systems depend in part on “write-before” relationships where some changes to stable storage are delayed until other changes commit. A journaled file system, for example, must commit a journal transaction before applying that transaction’s changes, and soft updates [9] and other consistency enforcement mechanisms have similar constraints, implemented in each case in systemt ways. We present a general abstraction, the patch, that makes write-before relationships explicit and file system agnostic. A patch-based file system implementation expresses dependencies among writes, leaving lower system layers to determine write orders that satisfy those dependencies. Storage system modules can examine and modify the dependency structure, and generalized file system dependencies are naturally exportable to user level. Our patch-based storage system, Featherstitch, includes several important optimizations that reduce patch overheads by orders of magnitude. Our ext2 proto...

• Type: Conference
• Year: 2007
• Where: SOSP
• Authors: Christopher Frost, Mike Mammarella, Eddie Kohler, Andrew de los Reyes, Shant Hovsepian, Andrew Matsuoka, Lei Zhang
• Keywords: Implementation Expresses Dependencies, Operating System, Reliable Storage Systems, Soft Updates-like Dependencies, SOSP 2007