Review - Total Recall - System Support for Automated Availability Management

This paper introduces Total Recall, a system that seeks to guarantee
user-specified availability in a P2P system based on the Chord DHT. P2P
systems deviate from traditional systems in that availability cannot be
predicted in the same way, primarily due to the presence of highly
transient nodes. The authors mainly propose two methods of guaranteeing
availability, and essentially compare lazy repair and eager repair.

The contribution of this paper is a prototype that provides automated
availability management based on changes in the system's underlying host
population. The main strength is the simplicity of the system. The
authors show that lazy repair performs better than eager repair and
still manages to meet availability guarantees while consuming acceptable
bandwidth for large files.

The shortcomings of this paper is its simplicity. I believe there is not
much innovation. The system proposes the obvious. OK, we need something
automated, so let's have a feedback system and a reaction based on the
feedback! The authors also have useless diagrams (Figure 1 and 2). They
definitely do not help the reader understand the system. Moreover the
proposed system is based on the assumption of good prediction
(availability prediction) that the dynamic repair engine base its
actions upon. Clearly from the evaluation, they fail to achieve this,
consuming one order of magnitude more bandwidth than an optimal system.
Last but not least, the authors motivate this system using heterogeneity
of hosts as one of their arguments. However, they fail to describe how
they solve this problem. Instead their evaluation is based on a
homogeneous system.

I believe that this paper is a non-contribution to the P2P research
community because of the above shortcomings. Moreover, no one would use
such a system even if it showed good performance. I would not want to
store my files on such a large scale distributed system primarily
because security is not addressed and security is an important issue.
Received on Thu Nov 24 2005 - 00:10:50 EST