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Other Storage Technology Options

Today's tape storage marketplace is made up of a confusing array of formats and technologies. OEMs and analysts agree that the situation is not serving customers well and have called for open formats. Open formats benefit customers by offering them multiple sources of product and media, and by providing a means to enable compatibility between products from different vendors.

Linear Tape-Open (LTO) Technology
Vendors such as Hewlett-Packard, IBM and Seagate have responded to this need for open formats by collectively developing new open format specifications based on the group's Linear Tape-Open (LTO) technology. The group developed the formats to serve multiple market areas and to be supported by multiple suppliers.

To best serve customers across the entire spectrum of applications, the three LTO was designed to accommodate a range of storage requirements from single server to complex network environments, in both fast-access and high-capacity formats. For this reason, two implementations of the technology were developed: Ultrium and Accelis.

Ultrium
The Ultrium tape format is the implementation of LTO technology optimized for high capacity and performance with outstanding reliability, in either a stand-alone or an automated environment. The Ultrium tape format uses a single reel cartridge to maximize capacity. It is ideally suited for backup, restore, and archive applications.

Accelis
The Accelis tape format is the implementation of LTO technology optimized for fast access to data, with exceptional reliability and performance characteristics. It uses a two-reel cartridge that loads at the middle of the tape to minimize access time. The Accelis tape format is targeted at automated environments and can enable a wide range of "on-line" data inquiry and retrieval applications.

Although there are differences between Ultrium and Accelis, developers and customers will benefit from the sharing of key technology characteristics of LTO through economies of scale for certain components, which should result in an overall cost benefit. Both format implementations of the LTO technology are available through open licenses to any vendor wishing to participate in developing tape products that interchange between other vendors' products of the same format.

Both the Ultrium and Accelis formats share the "best-of-breed" technology provided by LTO's advanced multi-track recording capability, head and servo technologies and high recording density. Although not specified, the characteristics of LTO were also defined to maximize the benefits of magneto-resistive (MR) head technology. The use of MR heads enables the high number of concurrent channels and the high track density characteristics of LTO. Apart from LTO, however, Ultrium and Accelis each have their own unique set of characteristics that make them well suited for their respective

Thus, ultimately it is the applications and their mission criticality that will determine the choice of technologies. "As organizations realize that the need to have all information online is no longer a matter of choice, they will need to build systems which store most of the information online. Customers, internal and external will become increasingly intolerant of unavailable systems. Which is when the need for intelligent storage will be increasingly appreciated.

When this happens, organizations will deploy technologies best suited to respond to customers (internal and external) instantly. Whether it is a SAN or a NAS or the Enterprise Storage Network, (ESN) the technology which facilitates this response is what will determine the choice of technologies", points out Srinivasan, country manager, EMC, Bangalore.

DLT Tapes
One of the most important trends in the tape environment is the user demand for a range of compatible products that address different performance, functionality, and price requirements. Users want a single solution that works at many levels, not a different format for every situation. DLT tape technology offers a broad range of choices, ranging from stand-alone drives, to single-drive, multi-cartridge loaders, to very large libraries with multiple drives, multiple ports, and hundreds of cartridges, all sharing compatible media, drives, and storage management software.
From a performance point of view, the characteristics that distinguish DLTtape technology from other tape storage technologies are speed, capacity, and reliability. When compared to other mid-range technologies, DLTtape drives offer faster transfer rates (up to 6 Mbs native), DLTtape cartridges store more data (up to 40 Gb native capacity on a single cartridge), and DLTtape drives can run longer, under more demanding duty cycles (our specs reflect a 100 per cent duty cycle).

DLTtape drives use half-inch tape in a single-reel cartridge, eliminating wasted space. DLTtape is drawn from the cartridge along a gently curving path past the write-read-write head to the take-up reel, minimizing wear and abrasion. DLTtape drives use a computer-controlled dual-motor system that precisely controls tape acceleration, deceleration and write/read speed.

This system eliminates tape stress and is one important reason DLTtape can easily withstand a million passes.

Information is recorded on DLTtape in a serpentine linear format-recording begins at the start of the tape and records to the end; then the drive steps the head to the next track, reverses direction and records back to the beginning of the tape, and so on. DLTtape drives achieve high data transfer rates because data is written using multiple channels-enabling faster throughput, and allowing bad data blocks to be rewritten to an alternate channel.

One of the most important benefit of DLT tape drives is backup and archiving facilities. From home PCs to the largest computer systems and global networks, data backup is the insurance policy against hardware failure, human error, natural disasters, viruses, and theft. Some companies, especially those required by law to maintain historical records, archive data to special vaults or storage sites specially designed to protect valuable records.

While these specialty systems may be linked to a network system, they often don't rely directly on the network for their operation.

Another characteristic common to many vertical DLTtape applications is the use of graphics. DLTtape drives are perfect because they offer an economical way to quickly store and retrieve large graphics files.

A third characteristic that makes certain vertical applications ideal for DLTtape drive technology is high data volume. Applications such as data acquisition often require very high data transfer rates to keep pace with real-time events such as seismic recording, satellite telemetry, instrument output, and financial markets. These types of "firehose" applications demand high bandwidth that only DLT technology can provide cost-effectively.

NM - Information courtesy: vendors

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