Failure-Atomic Updates of Application Data in a Linux File System

We present the design, implementation, and evaluation of a file system mechanism that protects the integrity of application data from failures such as process crashes, kernel panics, and power outages. A simple interface offers applications a guarantee that the application data in a file always reflects the most recent successful fsync or msync operation on the file. Our file system furthermore offers a new syncv mechanism that failure-atomically commits changes to multiple files. Failure-injection tests verify that our file system protects the integrity of application data from crashes and performance measurements confirm that our implementation is efficient. Our file system runs on conventional hardware and unmodified Linux kernels and will be released commercially. We believe that our mechanism is implementable in any file system that supports per-file writable snapshots.