Membrane

Abstract

We introduce Membrane, a set of changes to the operating system to support restartable file systems. Membrane allows an operating system to tolerate a broad class of file system failures, and does so while remaining transparent to running applications; upon failure, the file system restarts, its state is restored, and pending application requests are serviced as if no failure had occurred. Membrane provides transparent recovery through a lightweight logging and checkpoint infrastructure, and includes novel techniques to improve performance and correctness of its faultanticipation and recovery machinery. We tested Membrane with ext2, ext3, and VFAT. Through experimentation, we show that Membrane induces little performance overhead and can tolerate a wide range of file system crashes. More critically, Membrane does so with little or no change to existing file systems, thus improving robustness to crashes without mandating intrusive changes to existing file-system code.

A History of the Virtual Synchrony Replication Model

“…The OS community has looked at fault tolerance at the level of the operating system itself (for example by making the OS tolerant of faulty device drivers and hardware [10][11] [12]), and tolerating damage to persistent storage structures so that the OS won't crash if you try to mount a corrupted file system [13]). We've explored ways to mirror applications: Tandem's original process pair concept [14], for example, or the more ambitious perfect mirroring that Stratus Computer did back in the late 1980's with their "pair and a spare" hardware architecture [15].…”