NASA Scientific and Technical Aerospace Reports

20040121022 COPAN Systems, Inc., Longmont, CO, USA
A New Approach to Disk-Based Mass Storage Systems
Guha, Aloke; NASA/IEEE MSST 2004 Twelfth NASA Goddard Conference on Mass Storage Systems and Technologies in
cooperation with the Twenty-First IEEE Conference on Mass Storage Systems and Technologies; April 2004, pp. 421-425;
In English; See also 20040121020; No Copyright; Avail: CASI; A01, Hardcopy
We present a new approach to create large-scale cost-effective mass storage systems using high-capacity disks. The
architecture is optimized across multiple dimensions to support streaming and large-block data access. Because I/O requests
in these applications are to a small fraction of data, we power-cycle drives as needed to create a very high-density storage
system. Data protection is provided through a new variant of RAID, termed power-managed RAID(TradeMark), which
generates parity without requiring all drives in the RAID set to be powered on. To increase bandwidth, the system employs
several concurrency mechanisms including load balancing I/O streams across many parallel RAID controllers. A number of
optimizations are made to the interconnection architecture and caching schemes that lowers the cost of storage to that of
typical automated tape library systems while exploiting the performance and reliability advantages of disk systems. Recent
results at COPAN Systems have proven the viability of this new storage category and product.
Author
Data Storage; Cost Effectiveness; Disks; Automatic Control
20040121023 Intransa, Inc., San Jose, CA, USA
Comparative Performance Evaluation of iSCSI Protocol over Metropolitan, Local, and Wide Area Networks
Dalgic, Ismail; Ozdemir, Kadir; Velpuri; Weber, Jason; Chen, Helen; Kukreja, Umesh; NASA/IEEE MSST 2004 Twelfth
NASA Goddard Conference on Mass Storage Systems and Technologies in cooperation with the Twenty-First IEEE
Conference on Mass Storage Systems and Technologies; April 2004, pp. 409-413; In English; See also 20040121020; No
Copyright; Avail: CASI; A01, Hardcopy
We identify the tunable parameters of iSCSI and TCP that affect the performance characteristics for local, metropolitan,
and wide area networks. Through measurements, we determine the effect of these parameters on the throughput. We conclude
that with the appropriate tuning of those parameters, iSCSI and TCP protocols maintain a good level of throughput for all types
of networks.
Author
Computer Systems Performance; Local Area Networks; Wide Area Networks; Protocol (Computers)
20040121025 Connecticut Univ., Storrs, CT, USA
Parity Redundancy Strategies in a Large Scale Distributed Storage System
Chandy, John A.; NASA/IEEE MSST 2004 Twelfth NASA Goddard Conference on Mass Storage Systems and Technologies
in cooperation with the Twenty-First IEEE Conference on Mass Storage Systems and Technologies; April 2004, pp. 185-191;
In English; See also 20040121020; No Copyright; Avail: CASI; A02, Hardcopy
With the deployment of larger and larger distributed storage systems, data reliability becomes more and more of a
concern. In particular, redundancy techniques that may have been appropriate in small-scale storage systems and disk arrays
may not be sufficient when applied to larger scale systems. We propose a new mechanism called delayed parity generation with
active data replication (DPGADR) to maintain high reliability in a large scale distributed storage system without sacrificing
fault-free performance.
Author
Data Storage; Distributed Parameter Systems; Redundancy
20040121026 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Hierarchical Storage Management at the NASA Center for Computational Sciences: From UniTree to SAM-QFS
Salmon, Ellen; Tarshish, Adina; Palm, Nancy; Patel, Sanjay; Saletta, Marty; Vanderlan, Ed; Rouch, Mike; Burns, Lisa; Duffy,
Daniel; Caine, Robert, et al.; NASA/IEEE MSST 2004 Twelfth NASA Goddard Conference on Mass Storage Systems and
Technologies in cooperation with the Twenty-First IEEE Conference on Mass Storage Systems and Technologies; April 2004,
pp. 177-183; In English; See also 20040121020; No Copyright; Avail: CASI; A02, Hardcopy
This paper presents the data management issues associated with a large center like the NCCS and how these issues are
addressed. More specifically, the focus of this paper is on the recent transition from a legacy UniTree (Legato) system to a
SAM-QFS (Sun) system. Therefore, this paper will describe the motivations, from both a hardware and software perspective,
for migrating from one system to another. Coupled with the migration from UniTree into SAM-QFS, the complete mass
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