Introduction of read delay or write delay in servers of a geographically distributed data processing system so that clients read up-to-date data

Abstract

Read delay or write delay is added to server computers of a geographically distributed data processing system so that when writing to a dataset occurs at a first server and reading from the dataset occurs at a second server, the sum of any delay of returning an acknowledgement of completion of each write request and any delay in the reading of data for each read request is at least the data transmission delay between the two servers. For certain client applications such as NFS, the added delay is sufficient to compensate for the transmission delay without the use of a conventional read lock, which would require a round-trip delay. The method can provide an up-to-date global view of the dataset at each of the servers. The method can also provide equal performance of read access and write access at each of the servers.