A remote copy network realizes low-cost multi-hop remote copying. Remote
copying is executed via a remote copy network (RCN) having a source edge
device connected to a source storage and a target edge device connected
to a target storage. Because the RCN is a network provided by a network
business, a user having a storage device can execute remote copying
without owning or managing the RCN. The source edge device receives
remote copy I/O from the source storage, creates a log entry to which a
sequential number is added, and sends the log entry to a target edge
device. The target edge device acquires the remote copy I/O from the
received log entry, and sends the remote copy I/O to the target storage
in the order of the sequential number.