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Storage Technology Options
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
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
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.
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.
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.
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.
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
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.
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.
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).
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
system eliminates tape stress and is one important reason
DLTtape can easily withstand a million passes.
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.
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
these specialty systems may be linked to a network system,
they often don't rely directly on the network for their
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.
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.
- Information courtesy: vendors