Energy Efficiency and Storage Flexibility in the Blue File System Edmund B Nightingale Jason Flinn University of Michigan

The Blue File System 2 Towards Ubiquitous Data Access Pervasive computing: anywhere anytime any device –Ubiquitous WiFi access –Mobile storage Barriers to pervasive data access: –Varying I/O performance –Energy hogs! –Stale, inconsistent data BlueFS overcomes these barriers

The Blue File System 3 Change is Constant Access times vary across storage devices Wireless networks are highly variable Power management affects performance BlueFS provides an adaptive cache hierarchy

The Blue File System 4 Power to the People Distributed file systems use power hungry devices Distributed file systems not designed for energy BlueFS “clean sheet design” for energy efficiency

The Blue File System 5 You Can Take it with You Want to leverage the benefits of portable storage Portable storage is not a mobile data panacea –Can be lost, stolen, damaged –Sharing is hard –More replication = higher chances of stale/inconsistent data BlueFS integrates portable storage into file system

The Blue File System 6 Organization Motivation The Blue File System Evaluation Related Work Conclusion

The Blue File System 7 > /BlueFS/ The Blue File System BlueFS Server Local disk Work Home

The Blue File System 8 To BlueFS Server Unlink 1 2 Create 1 2 Mkdir 1 2 Write to Many Asynchrony improves performance Aggregating writes saves energy VFS Ops BlueFS To microdrive Write 2 1

The Blue File System 9 Read From Any BlueFS monitors cost of reading data from each device Pick device best performance, least energy > cat /BlueFS/foo BlueFS BlueFS Server Blk 2 Blk 1 Micro drive

The Blue File System 10 Power Management BlueFS integrated with power management strategies When a device transitions, BlueFS is notified Self Tuning Power Management BlueFS HintsState Transitions

The Blue File System 11 Hiding device transitions 1) Network accesses Disk 2) Ghost hints issued3) Disk spins up 5) Network transitions to PSM Network 4) Disk accesses begin

The Blue File System 12 Cache Management Storage devices treated as cache BlueFS decides which files to cache When a device fills up, LRU used to make space Affinity: file always on portable storage

The Blue File System 13 Cache Consistency > /BlueFS/ BlueFS Server Local disk Work Home Local disk

The Blue File System 14 Evaluation Goals –How does performance of BlueFS compare to other DFS? –What benefit does an adaptive cache hierarchy provide? –How well does BlueFS support portable storage? –How much does BlueFS reduce client energy usage? –How does BlueFS perform with heterogeneous storage?

The Blue File System 15 Comparing BlueFS to other DFS BlueFS 10x faster than NFS, 16% faster than Coda WD Andrew benchmark: Untar, configure, make, delete Apache source

The Blue File System 16 Benefits of Adaptive Cache Hierarchy BlueFS reads 4k files up to 60x faster than ext2 Read various files with the disk in standby mode

The Blue File System 17 Support for Portable Storage BlueFS 44% faster than Lookaside, up to 3x faster for high latency Ran a file system trace as fast as possible using portable storage

The Blue File System 18 Energy Efficient Data Access Reduces interactive delay 76%, 55% less energy than Coda Ran first 10,000 ops of Purcell trace with half full cache Ran first 10,000 ops of Purcell trace with half full cache

The Blue File System 19 Heterogeneous Storage With flash BlueFS reduces interactive delay 48%, 25% less energy Added 16 MB flash to BlueFS, ran Purcell with full local cache

The Blue File System 20 Related Work AFS [Howard et al] Coda [Kistler et al] & lookaside caching [Tolia et al] PersonalRAID [Sobti et al] Segank [Sobti et al] Cooperative I/O [Weissel et al] LBFS [Muthitacharoen et al]

The Blue File System 21 Conclusions BlueFS enables ubiquitous data access by: –Adapting to device characteristics –Reducing mobile computer energy usage –Seamlessly integrating portable storage Source:

The Blue File System 22 System Architecture Applications BlueFS Kernel Module Wolverine Linux Kernel Linux File Cache USB Stick Card Flash Micro- drive Local Disk To BlueFS Server VFS Operations Up-call

The Blue File System 23 BFS Kernel Intercepts Linux VFS calls –Communicates with Wolverine through pseudo-device driver Caches and invalidates data & metadata in Linux file cache Operations redirected to Wolverine –Enables support for devices with different consistency semantics