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

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

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

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

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

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

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

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

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

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

Hiding device transitions 5) Network transitions to PSM 1) Network accesses Network 2) Ghost hints issued 3) Disk spins up 4) Disk accesses begin Disk The Blue File System

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

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

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

Comparing BlueFS to other DFS Andrew benchmark: Untar, configure, make, delete Apache source 6000.0 BlueFS 10x faster than NFS, 16% faster than Coda WD The Blue File System

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

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

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

Heterogeneous Storage Added 16 MB flash to BlueFS, ran Purcell with full local cache First two bars we’ve already seen on previous slide. With flash BlueFS reduces interactive delay 48%, 25% less energy The Blue File System

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

Conclusions BlueFS enables ubiquitous data access by: Adapting to device characteristics Reducing mobile computer energy usage Seamlessly integrating portable storage Source: http://notrump.eecs.umich.edu/group/group.html The Blue File System

System Architecture The Blue File System Linux Kernel Wolverine Applications BlueFS Kernel Module Wolverine Linux Kernel Linux File Cache USBStick CardFlash Micro-drive Local Disk To BlueFS Server VFS Operations Up-call Mention Read from any write to many semantics The Blue File System

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 The Blue File System