TotalCOW

Xingbo Wu, Wenguang Wang, Song Jiang
2015 Proceedings of the 6th Asia-Pacific Workshop on Systems - APSys '15  
Modern file systems leverage the Copy-on-Write (COW) technique to efficiently create snapshots. COW can significantly reduce demand on disk space and I/O bandwidth by not duplicating entire files at the time of making the snapshots. However, memory space and I/O requests demanded by applications cannot benefit from this technique. In existing systems, a disk block shared by multiple files due to COW would be read from the disk multiple times. Each block in the reads is treated as an independent
more » ... d as an independent one in different files and is cached as a sperate block in memory. This issue is due to the fact that current file access and caching are based on logic file addresses. It poses a significant challenge on the emerging light-weight container virtualization techniques, such as Linux Container and Docker, which rely on COW to quickly spawn a large number of thin-provisioned container instances. We propose a lightweight approach to address this issue by leveraging knowledge about files produced by COW. Experimental results show that a prototyped system using the approach, named TotalCOW, can significantly remove redundant disk reads and caching without compromising efficiency of accessing COW files.
doi:10.1145/2797022.2797024 dblp:conf/apsys/WuWJ15 fatcat:vrthpqrjnvat3cctf33lnerdpi