Paper #: Week 12 Paper 2 
Title: FARSITE: Federated, Available, and Reliable Storage for an Incompletely trusted environment.

(1) Problems
This paper is an overview of the design of Farsite. Farsite is a file system which serves as a centralized storage but is not actually centralized. 
The file server is distributed among a network of untrusted network desktop workstations and provides secure reliable service by using a variety of techniques
 like cryptography, randomized replication, Byzantine fault tolerance etc. Therefore the problem that Farsite addresses is of a client server paradigm and 
tries to leverage of hard disk space and computational power of the workstations that form the network.


(2) New Idea and Strengths
i) The basis of the paper is good. A centralized server serves as a single point of failure and techniques to combat this widespread problem are needed.
ii) The authors do a great job of explaining their system in easy to understand language. Aspects covered are explained in detail and the readers are kept interested. 
iii) The design of using client workstations as the storage (after conducting studies which showed that nearly 50% of disk space on client workstations is unused) 
makes sense. 
iv) The authors discuss the entire design of their work and also earmark aspects that have already been implemented and ones which have not. This is a good 
practice as the reader is not left wondering.
v)The performance measurements show pretty good results. Though the system is not implemented 100% - the results are impressive.
vi) The authors also clearly outline what their network their system would be ideal for. 
All in all, Farsite looks like a well thought out system.

(3) Weaknesses and Extensions
i) The performance measurements are carried out on an a network of only five machines. This is not a real world scenario as per their design 
(they are aiming for a ~10^5 node network.) so their results might not be upto the mark.
ii) As the authors themselves state, Farsite does not efficiently support large scale write sharing of files. A scenario where users need this
 facility is easily possible. 
iii) It is also pointed out that data is lost permanently if too many machines fail within a small amount of time (so that regeneration is not possible). 
Though rare, Farsite should definitely tackle this problem.


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