  Classical erasure codes, e.g. Reed-Solomon codes, have been acknowledged as
an efficient alternative to plain replication to reduce the storage overhead in
reliable distributed storage systems. Yet, such codes experience high overhead
during the maintenance process. In this paper we propose a novel erasure-coded
framework especially tailored for networked storage systems. Our approach
relies on the use of random codes coupled with a clustered placement strategy,
enabling the maintenance of a failed machine at the granularity of multiple
files. Our repair protocol leverages network coding techniques to reduce by
half the amount of data transferred during maintenance, as several files can be
repaired simultaneously. This approach, as formally proven and demonstrated by
our evaluation on a public experimental testbed, enables to dramatically
decrease the bandwidth overhead during the maintenance process, as well as the
time to repair a failure. In addition, the implementation is made as simple as
possible, aiming at a deployment into practical systems.
