  The Grid Datafarm architecture is designed for global petascale
data-intensive computing. It provides a global parallel filesystem with online
petascale storage, scalable I/O bandwidth, and scalable parallel processing,
and it can exploit local I/O in a grid of clusters with tens of thousands of
nodes. One of features is that it manages file replicas in filesystem metadata
for fault tolerance and load balancing.
  This paper discusses and evaluates several techniques to support
long-distance fast file replication. The Grid Datafarm manages a ranked group
of files as a Gfarm file, each file, called a Gfarm file fragment, being stored
on a filesystem node, or replicated on several filesystem nodes. Each Gfarm
file fragment is replicated independently and in parallel using rate-controlled
HighSpeed TCP with network striping. On a US-Japan testbed with 10,000 km
distance, we achieve 419 Mbps using 2 nodes on each side, and 741 Mbps using 4
nodes out of 893 Mbps with two transpacific networks.
