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Development of Secondary Archive System at Goddard Space Flight Center Version 0 Distributed Active Archive CenterThe Goddard Space Flight Center (GSFC) version 0 Distributed Active Archive Center (DAAC) has been developed to support existing and pre Earth Observing System (EOS) Earth science datasets, facilitate the scientific research, and test EOS data and information system (EOSDIS) concepts. To ensure that no data is ever lost, each product received at GSFC DAAC is archived on two different media, VHS and digital linear tape (DLT). The first copy is made on VHS tape and is under the control of UniTree. The second and third copies are made to DLT and VHS media under a custom built software package named 'Archer'. While Archer provides only a subset of the functions available with commercial software like UniTree, it supports migration between near-line and off-line media and offers much greater performance and flexibility to satisfy the specific needs of a data center. Archer is specifically designed to maximize total system throughput, rather than focusing on the turn-around time for individual files. The commercial off the shelf software (COTS) hierarchical storage management (HSM) products evaluated were mainly concerned with transparent, interactive, file access to the end-user, rather than a batch-orientated, optimizable (based on known data file characteristics) data archive and retrieval system. This is critical to the distribution requirements of the GSFC DAAC where orders for 5000 or more files at a time are received. Archer has the ability to queue many thousands of file requests and to sort these requests into internal processing schedules that optimize overall throughput. Specifically, mount and dismount, tape load and unload cycles, and tape motion are minimized. This feature did not seem to be available in many COTS pacages. Archer also uses a generic tar tape format that allows tapes to be read by many different systems rather than the proprietary format found in most COTS packages. This paper discusses some of the specific requirements at GSFC DAAC, the motivations for implementing the Archer system, and presents a discussion of the Archer design that resulted.
Document ID
19960052743
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Sherman, Mark
(Hughes STX, Inc. Greenbelt, MD United States)
Kodis, John
(Hughes STX, Inc. Greenbelt, MD United States)
Bedet, Jean-Jacques
(Hughes STX, Inc. Greenbelt, MD United States)
Wacker, Chris
(Hughes STX, Inc. Greenbelt, MD United States)
Woytek, Joanne
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Lynnes, Chris
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1996
Publication Information
Publication: Fifth NASA Goddard Conference on Mass Storage Systems and Technologies
Volume: 2
Subject Category
Documentation And Information Science
Accession Number
96N35815
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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