Real-time, self-managing data flows -- Unidata will foster and support the existence of real-time data flows that encompass a broad range of Earth-system phenomena, can be accessed with ease by all constituents, and are self managing in respect to changing contents and user needs.
--A goal of Unidata 2008: Shaping the Future of Data Use in the Geosciences
The cluster approach to toplevel IDD relay, first reported in the Spring 2005 status report, has been operational at the UPC since early summer 2005. The cluster, described in the June 2005 CommunitE-letter article Unidata's New IDD Cluster, routinely relays data to between 250 and 290 downstream connections at an average rate of approximately 170 Mbps (~1.8 TB/day), with peak rates routinely exceeding 290 Mbps (~3 TB/day). Live stress testing of the cluster demonstrated that the limiting factor for data relay was the local network bandwidth which is 1 Gbps at UCAR!
We consider the cluster setup to still be experimental. Configurations change as we learn more about how the system performs.
The cluster approach to IDD relay has been adopted by NOAA/GSD (formerly FSL) and is being implemented at Penn State with funds provided by the Unidata-administered Equipment Awards program. Recently, Unidata staff have fielded questions on implementing similar clusters at Unidata community sites (Texas A&M and University of Nebraska-Lincoln) that have expressed an interest in functioning as toplevel IDD relay nodes.
Steve Emmerson is working on a replacement system for the LDM (codenamed "Hermes") that will combine the best features of the LDM, INN (i.e., netnews), and more modern peer-to-peer systems such as BitTorrent. The work is currently in the design stage. Design features include
NB: In order to correctly gauge real-time status of the IDD, it is important that all participating sites accurately maintain their system clocks. This is easily done through use of a Network Time Protocol daemon run on the local machine.