Distributed File Systems Chad Griffith Characteristics Present Work Future Work

Key Characteristics Dispersion of Users and Files Multiplicity of Users and Files

Transparency (Dispersed Users) Login Transparency Uniform login Uniform file system view Access Transparency Uniform file access, local or remote

Dispersed Files Location transparency Location independence

Multiplicity of Users Concurrency Transparency File sharing between multiple concurrent users NO adverse effects from this Transaction based requires appearance of isolation Concurrency control Ensures concurrent execution of a transaction

Multiplicity of Files Files may be replicated for: Redundancy Concurrent access for efficiency Replication transparency Perform atomic updates on replicated files Users only ”see” 1 copy of the file

Other Characteristics Applies to DFS and distributed systems Fault Tolerance Scalability Heterogeneity

Current Works TidyFS (Microsoft) For parallel computations on clusters Emphasizes simplicity and small size Has metadata server, node service, and TinyFS explorer Tighter integration vs generality

Current Works GFS (Google file system) Observance of app workloads and environment Emphasizes large files and datasets Appends new data vs modifying data Co-designed with the applications that are to be run on GFS

Current Works HDFS (HaDoop) Large files and datasets Streaming file access No appending of files yet Portability (more generalized) Master/slave architecture

Current Works Tahoe-LAFS Peer to peer application Pools HD space with friends Auto encryption Open source (GPL license) Central node needed still

Future Works OS Independent DFS Communication independent DFS Can detect file system and type and read from any system Possibly can even learn about new file systems independently or from online accessible database Communication independent DFS File systems and communication systems will be more robust so that files can be accessed over different communications protocols

References Distributed Operating Systems & Algorithms, by Randy Chow and Theodore Johnson, 1997. Http://research.microsoft.com/jump/81486 Http://labs.google.com/papers/gfs.html hadoop.apache.org/