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Beyond Optical Storage
If you have some, you want more. And if you have more, you want it all. Which is why now optical media too seems to have lost it to holographic media
Wednesday, March 08, 2006
For long we stored data on the surfaces, but today the technology
has moved to volumes. Since the storage needs are increasing exponentially,
technology improvements in current storage media are saturating. And even when
we think that the Blu-Ray disks and HD-DVD would be sufficient to satiate the
storage needs, there is need for more. And that's where the concept of
holographic storage comes from. With volume intensive optical and holographic
storage media coming into the foray, it's no longer that the data need be
stored in layers. Rather it can now be stored all across the thickness of the
storage media, thus, drastically increasing the amount of data that can be
stored on, say, a disk. This has led to a compelling increase in the amount of
data that can be stored over the same size of the disk.
What's holography?
But what is meant by holographic storage? Holography is a
branch of optics where the highly coherent laser beam is used. And it is the
three-dimensional nature of holography that enables the superimposing many
layers/pages of data in the same volume of the material using a single beam of
light. Also, holography has the potential for fast transfer rates and fast
random access times. This is because the data are stored and recovered in
parallel-typically 1 million bits at a time.
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Reading
and writing data
Now lets get into a little more detail and see how the
holographic storage works. As mentioned earlier, the laser beam is used as a
carrier to store data as holograms. For those who know not, holograms are the
interference patterns created in the process. So the laser beam is split into
two-a signal beam that carries the data, and the reference beam. Spatial light
modulators (SLMs) are used to translate the data onto the signal beam. The SLM
encodes the digital data (1s and 0s) into a pattern of light and dark pixels in
an array or page. One such array contains about a million bits. A hologram is
then formed on a photosensitive recording media at a place where the reference
beam and the signal beam carrying data intersect.
Now you must be wondering how the high density of the
holographic media is achieved. Well that's done by varying the position of the
storage medium, wavelength, or the angle at which reference beam meets the
signal beam. That's how comparatively large amounts of data can be stored over
a single disk.Reading the data is equally easy. The data can be recovered
through the hologram reconstructed from the beam that is reflected from the
reference beam at the detector medium.
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Vendor Speak |
| Manish
Bapat, EMC |
| Disaster recovery and business continuity became a buzzword in the industry post the 9/11 attacks. In the recent past natural calamities like hurricane in the US, the Tsunami in Asian region, the mammoth floods in Mumbai, the earthquake in India and Pakistan has dramatically impacted the thought process of organizations worldwide and in India. For organizations across verticals viz software, telecom, manufacturing, insurance, healthcare, finance/banking or government domain DR and BC has become a top priority. Enterprise Content Management has also become an imperative for enterprises in India driven by the unprecedented growth in data, including structured, semi-structured, and unstructured information which is estimated to grow approximately 50 percent per
year.
Enterprises in India are also facing a huge email explosion and hence have to adopt effective e-mail management and archiving solutions, They need to implement a centralized data storage and retrieval system that makes enterprise e-mail easier to administer and use. CAS (Content Addressed Storage) can eliminate the need for additional resources to perform data management and data-protection activities, and dramatically lower the total cost structure for fixed content. Its plug-and-play scalability automatically recognizes additional capacity as it is added, and its online capability makes it possible to retrieve data from anywhere on the network-anytime.
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Challenges
Some optical storage media products have already become
hits in the consumer space, the latest entry in the product line is the H-ROM
(Holographic ROM) that stores data on the tapestry HDS (Holographic Data
Storage) media. This is the latest addition to the media product family that
includes green laser HDS3000 media, and blue laser HDS5000 media.
While the media products are now being targeted at its
applications in high-end archiving of data centers, financial institutions,
security and surveillance, and for storing medical data where the data is
currently being stored and archived on magnetic tapes. Magnetic tapes lag behind
the optical media for two main reasons: one, it is harder to access data on
magnetic tapes though they can store large amounts of data and two, they are
less durable for they can store data in good shape for 10 years against the 50
years pitched in by the holographic media.
So the optical and holographic storage media can be used to
replicate, archive and broadcast high-definition videos. So you can imagine the
complete Star Trek series being shipped to you over a single disk with a few
complementary movies in it. And pirates beware! The data on holographic disks is
difficult to copy since it requires the same expensive equipment to replicate it
as is needed to create the original. Another big issue concerns the storage
material used. Since hologrpahy involves laser beams to write the data in
various patterns on a photosensitive material, all the precautions need to be
taken to protect the photosensitive material from getting spoilt. As a result,
the data disks have to kept away from light till a negative film is prepared,
just like any other photographic plate. Even the most efficient of technologies
have become omnipresent only when they have become affordable to the masses. And
holographic media is no exception. So just wait and watch to see how things
unfold on the cost and reliability platforms, and the H-ROM comes at the price
of a CD today.
For long we stored data on the surfaces, but today the
technology has moved to volumes. Since the storage needs are increasing
exponentially, technology improvements in current storage media are saturating.
And even when we think that the Blu-Ray disks and HD-DVD would be sufficient to
satiate the storage needs, there is need for more. And that's where the
concept of holographic storage comes from. With volume intensive optical and
holographic storage media coming into the foray, it's no longer that the data
need be stored in layers. Rather it can now be stored all across the thickness
of the storage media, thus, drastically increasing the amount of data that can
be stored on, say, a disk. This has led to a compelling increase in the amount
of data that can be stored over the same size of the disk.
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