Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: G.C. Silaghi, F. Araujo, L.M. Silva, P. Domingues, A.E. Arenas
Editorial: IEEE Computer Society, 22nd IEEE International Symposium on Parallel and Distributed Processing, IPDPS, 2008.
Desktop Grid systems reached a preeminent place
among the most powerful computing platforms in the
planet. Unfortunately, they are extremely vulnerable to mischief,
because volunteers can output bad results, for reasons
ranging from faulty hardware (like over-clocked CPUs) to
intentional sabotage. To mitigate this problem, Desktop
Grid projects replicate work units and apply majority voting,
typically on 2 or 3 results.
In this paper, we observe that this form of replication is
powerless against malicious volunteers that have the intention
and the (simple) means to ruin the project using some
form of collusion. We argue that each work unit needs at
least 3 voters and that voting pools with conflicts enable the
master to spot colluding malicious nodes. Hence, we postprocess
the voting pools in two steps: i) we use a statistical
approach to identify nodes that were not colluding, but submitted
bad results; ii) we use a rather simple principle to
go after malicious nodes which acted together: they might
have won conflicting voting pools against nodes that were
not identified in step i. We use simulation to show that our
heuristic can be quite effective against colluding nodes, in
scenarios where honest nodes form a majority.
Cuvinte cheie: desktop grids, sabotage tolerance, collusion