Scalable high-density data-storage systems handle bulky image files

High-resolution image and video files are prodigious consumers of storage space, whether they are archived or stored temporarily for subsequent processing and data reduction. Consequently, developers of imaging systems are turning to innovative data-storage architectures that can be scaled to meet growing storage requirements while maintaining connectivity with the gamut of host computers--from desktops to massively parallel processors.

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Scalable high-density data-storage systems handle bulky image files

By Rick Nelson, Contributing Editor

High-resolution image and video files are prodigious consumers of storage space, whether they are archived or stored temporarily for subsequent processing and data reduction. Consequently, developers of imaging systems are turning to innovative data-storage architectures that can be scaled to meet growing storage requirements while maintaining connectivity with the gamut of host computers--from desktops to massively parallel processors.

Storage capacity and access time are key specifications for today`s high-performance storage systems, which can accommodate a few gigabytes to tens of terabytes of data. While a redundant array of independent disks (RAID) is one technology providing reliable, scalable storage, other interface technologies such as Fibre Channel and UltraSCSI are also providing high-speed transfers of stored data on demand.

Storage-product vendors are therefore tailoring their high-speed and high-capacity devices for the data-storage market. For example, IBM Corp. has tackled the raw-capacity challenge by providing an 8.4-Gbyte hard-disk drive for desktop personal computers (PCs). Called Deskstar 8, it is the first desktop PC drive to use IBM`s magneto-resistive extended head technology, which packs 1.74 billion bits per square inch (see Fig. 1). The Deskstar 8 is well suited for video applications where one minute of video information requires 200 Mbytes of storage.

Networked access

While stand-alone PC disks make up only a small part of enterprise storage solutions, many corporations prefer to install networked data access using disk subsystems. Addressing this effort, Ciprico (Minneapolis, MN) recently demonstrated the storage of nearly one hour of uncompressed video on a single Fibre Channel RAID disk array. The company also previewed a network digital disk recorder--a bundled package combining a Silicon Graphics` workstation with a RAID-3 disk array. Moreover, it debuted Halo, a bundled RAID Fibre Channel storage system for Sun Microsystems` platforms. The bundled package includes Ciprico`s 7000 Fibre Channel disk array, an S-Bus to Fibre Channel host bus adapter, and Ciprico`s graphical user interface software utilities to support storage administration, such as for medical images, directly from a Sun workstation.

The CLARiiON (Southboro, MA) VF2000 disk array supports up to four simultaneous video streams from a single storage system. This disk array can be configured to store more than 200 hours of video while providing fault tolerance, continuous data access, and support for hot-swapping failed components. Sequential read performance exceeds 30 Mbyte/s, whereas sequential write performance tops 22 Mbyte/s.

The VF2000, based on a RAID-3 engine, of fers a raw storage capacity of 176 Gbytes for a deskside model and up to 704 Gbytes for a rack-mount version. CLARiiON has also entered into a strategic reselling agreement with Avid Sports (Lowell, MA), a digital-video-technology vendor serving the sports industry. Avid Sports is planning to resell CLARiiON FC5000 Series Fibre Channel disk arrays to sports teams, athletic departments, and organized leagues to assist coaches and players in analyzing games, scouting opponents, and improving player development.

This disk-array series is based on the company`s multidimensional storage architecture, a Fibre Channel-based framework. The architecture implements application-configured storage pools that can be scaled independently in five dimensions: capacity, input/output (I/O) performance, data throughput, connectivity, and data availability.

On the interface side, the Emulex (Costa Mesa, CA) LightPulse Fibre Channel PCI host adapter for Sun Ultra 30 PCI I/O-based workstations provides Fibre Channel rates of 266 Mbit/s, 531 Mbit/s, and 1.062 Gbit/s (see Fig. 2). It also supports point-to-point, arbitrated-loop, and switched-fabric Fibre Channel topologies. Developed in conjunction with CLARiiON and Orca Systems (Watertown, MA), LightPulse supports both the CLARiiON Series 3000 SCSI disk array and the CLARiiON FC5000 Series Fibre Channel disk array.

For UltraSCSI support, Baydel (Leatherhead, England) has a 40-Mbyte/s interface for its O/ESR RAID systems that makes its RAID systems compatible with UltraSCSI host adapters. The company targets its drives at the prepress, film/video, petrochemical, and medical-imaging industries, and has designed the 40-Mbyte/s interface to permit smooth upgrades for users of its previous-generation controllers.

Other considerations

Speed and capacity considerations alone are not adequate for choosing the optimum data-storage solution for complex applications. CLARiiON`s MSA technology is one of many efforts to address other considerations, such as data protection, upward migration, scalability, and open interface capabilities.

Driving the demands for these requirements is the consolidation of enterprise data. That consolidation can be in physical form, in which data are concentrated in a central storage system such as the EMC Corp. (Hopkinton, MA) Symmetrix, or in virtual form, in which physically distributed data subsystems are linked via storage-management software-like packages such as that from Legato Systems (Palo Alto, CA).

In turn, data consolidation, either virtual or physical, is being driven by the emergence of cross-platform database architectures such as Oracle Corp.`s Oracle8, which aim to distribute mainframe-level database services across distributed open platforms. Oracle8 is the company`s universal data server and the basis of its network computing architecture, in which data are shared among the gamut of computer platforms, from enterprise servers to low-end, low-cost PCs.

Oracle8 has attracted a plethora of hardware and software storage solutions. Legato Systems is delivering a new version of its BusinesSuite Module to support on-line backup of Oracle8 data on Windows NT and UNIX platforms. This module backs up Oracle data while the database application remains on-line, allowing users continuous access to their Oracle8 applications. In conjunction with Legato NetWorker, the module also offers features like autochanger support, automated media labeling and tracking, and media cloning to help implement local and off-site storage strategies.

Legato`s approach, embodied in the company`s GEMS architecture, is an effort to reconcile the conflicting demands of distributed data storage for application development and access and centralized control for data-protection operations. Contending that a fully centralized storage-management function is impractical for many customer environments, Legato`s approach enables a few control zones at optimum locations to be distributed among many data zones to ensure that network bottlenecks do not interfere with data-protection tasks.

Enterprise storage

Also providing support for Oracle8 are Hewlett-Packard and EMC Corp., which are providing Oracle8 high-end hardware platforms and enterprise storage systems, respectively. The combination targets large-scale decision-support systems and on-line transaction processing applications involving multimedia and object-based technologies. The platform has the scalability to support databases from gigabytes to terabytes while handling systems ranging from single users to tens of thousands of users. A combined Hewlett-Packard and EMC configuration has been deployed on a four-node HP 9000 Enterprise Server cluster running the HP-UX operating system with 5 Tbytes of EMC`s Symmetrix 3000 integrated cached disk arrays.

The EMC Symmetrix enterprise storage systems provide simultaneous support of up to 32 heterogeneous servers and up to 3 Tbytes of capacity in a single system. They offer a variety of selectable levels of information management, protection, and sharing capabilities.

Despite the support of Oracle8 by both companies, the EMC Symmetrix system competes directly with Hewlett-Packard`s OpenView OmniStorage system for HP 9000 systems. The OmniStorage system is a client/server-based hierarchical storage-management system that addresses the price/performance storage-system gamut by combining magnetic-disk, optical-disk, and magnetic-tape storage technologies.

OmniStorage automatically migrates infrequently used data to relatively inexpensive secondary tape and optical-disk media, keeping fast but expensive magnetic storage free for new, critical, frequently accessed data. Although users accessing secondary media may notice a slight time delay, they do not need to track the details of the secondary media, or even be aware that they are accessing secondary media. Migration through the hierarchy can be controlled dynamically by file size and access time, and individual files or complete directories can be excluded from migration.

Write once, read many disks and rewriteable magneto-optical disks can coexist and be used simultaneously in one OmniStorage optical jukebox. The relationship between data and media is configurable and determines which data will be migrated to which media. The OmniStorage file system can be exported to other systems in the network. This function is available for Hewlett-Packard and non-Hewlett-Packard systems supporting Sun Microsystems NFS, including Windows NT and PC operating systems.

Digital Equipment Corp. (Maynard, MA), an UltraSCSI pioneer, is also using the Fibre Channel in its StorageWorks Fibre Channel RAID subsystems (see Fig. 3). OEM customers are evaluating the systems for use in medical-imaging and data-warehousing applications. The StorageWorks subsystems provide one or two controllers and data rates to 100 Mbyte/s. They support up to 72 drives, providing more than 655 Gbytes of storage for data-intensive applications and up to 1 Gbyte of on-board, mirrored cache.

Successful storage implementations are expected to increasingly rely on support for open multivendor computer architectures. Demands for dedicated storage solutions are projected to expand markedly as the envisioned data-processing explosion outpaces the storage capacities of PC- and server-resident disk drives.

To capture a portion of the rising data-storage product market, CPU vendors such as Digital Equipment Corp., IBM, and Hewlett-Packard continue to evolve their data-storage products toward compatibility with other vendors` platforms. For example, Digital`s StorageWorks subsystems already support its own company and Hewlett-Packard and Sun Microsystems UNIX-based systems. Next, Digital is working on supporting Microsoft Windows NT and IBM systems. Furthermore, IBM plans to expand its Seascape architecture to support mixed multivendor host servers while concurrently enabling remote Web-based storage management.

A major part of the storage solution is investment protection. For instance, CLARiiON estimates that the actual life of a storage device is twice that of an average PC server. Consequently, an optimum storage system should be able to serve two generations of CPU hardware.

FIGURE 1. The IBM Corp. 8.4-Gbyte hard-disk drive for desktop computers uses IBM`s magneto-resistive extended head technology to pack 1.74 billion bits per square inch. Called the Deskstar 8, the drive can accommodate video applications where one minute of video information requires 200 Mbytes of storage.

FIGURE 2. The Emulex LightPulse Fibre Channel PCI host adapter can achieve data-transmission rates of 266 Mbit/s, 531 Mbit/s, and 1.062 Gbit/s while supporting point-to-point, arbitrated-loop, and switched-fabric topologies. Developed in conjunction with CLARiiON and Orca systems, LightPulse adapters support both the CLARiiON Series 3000 SCSI disk array and the CLARiiON FC5000 Series Fibre Channel disk array.

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FIGURE 3. The StorageWorks systems from Digital Equipment Corp. include Fibre Channel and UltraSCSI interfaces. This RAID enclosure for office environments handles up to 72 of the company`s RAID disks, each of which can store 9 Mbytes of data.

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