HighLight: Using a Log-structured File Systemfor Tertiary Storage Management

Abstract Robotic storage devices offer huge storage capacity at alow cost per byte, but with large access times. Integrating these devices into the storage hierarchy presents a chal-lenge to file system designers. Log-structured file systems (LFSs) were developed to reduce latencies involved in ac-cessing disk devices, but their sequential write patterns match well with tertiary storage characteristics. Unfortu-nately, existing versions only manage memory caches and disks, and do not support a broader storage hierarchy. HighLight extends 4.4BSD LFS to incorporate both sec-ondary storage devices (disks) and tertiary storage device