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

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

8. 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

9. 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

10. 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

11. 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

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 Work Home > /BlueFS/ > /BlueFS/ Local disk
BlueFS Server
> /BlueFS/
> /BlueFS/
Local disk
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
Andrew benchmark: Untar, configure, make, delete Apache source
6000.0
BlueFS 10x faster than NFS, 16% faster than Coda WD
The Blue File System

16. 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

17. 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

18. 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

19. 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

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 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

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
The Blue File System