Recent developments have made some optical devices very affordable,
even for the smaller organisation, with genuine improvements in
productivity and efficiency
With the increasing complexity and storage requirements of
applications and networks, a viable alternative to conventional
hard disk storage is often required to cater for these demands. As
well as this, many clients are also looking for electronic storage
and distribution of data rather than the more conventional format
of paper. To add even more demands to the storage requirements is
the fact that many applications now incorporate not only full
colour images which may take 10 to 20 megabytes, but also large
databases, scanned documents, and emerging multimedia and
animations which are only one step away from a virtual reality
environment.
However, storing and delivering this information now requires a
more innovative use of available technology to satisfy customer
expectations as well as improving productivity at the source of
this information, which is not an enviable task for IT
professionals. This is due to technology mispositioning as well as
misconceptions that exist as a result of vendors failing to supply
the negative aspects to a particular technology as well as the
benefits.Probably the most common technology that many offices
currently use is CD-ROM, especially in the area of applications
software and reference jukeboxes for images. One only has to
install a complex software package from floppy disks to begin to
appreciate the benefits of a storage medium where a single disc can
hold up to 650Mbytes of data! But the question remains - what can
these new technologies actually provide in addition simply to
distributing application software? The different approaches need to
be addressed to appreciate fully what a particular subset of
optical storage will actually deliver, not what the vendor
promises. Indeed, one of the historic problems has been that a
single technology vendor will try to broaden a product's appeal to
a wider audience, simply because that vendor cannot supply the best
solution for a particular problem. Without understanding some of
the fundamentals, the user has little option but to go along with a
lot of promises encompassed in technical jargon which does little
to instil confidence.The most important area to explore is how to
increase the secondary storage issue so that client data which is
inactive (completed projects) can be moved to a more economical
medium, therefore freeing up valuable primary hard disk storage.
The first essential is to try and adopt a medium that is a
"computer peripheral" type of product. This generally excludes
recordable CDs which will be looked at in more detail. This leaves
either magneto-optical or phase-change optical drives as the
obvious choices. These drives behave in much the same way as a
conventional storage peripheral with data sectors being addressable
individually for both reading and writing. The primary difference
is that magneto-optical drives require two revolutions of the disc
to rewrite data, whereas phase-change rewrites in a single pass.
However, as with any computer storage device, do not rely on any
single medium for both backup, archive or even live copies of the
data. No storage medium is infallible and adequate backup/copy
procedures should be followed. An additional point to consider is
that many optical drive vendors have now taken away the default
option of recording data with data verify enabled. Naturally, this
increases perceived performance, but what happens if three years
later the data is unreadable due to, say, a media flaw that was
undetected at the time of writing?All this apart, placing an
optical drive at either the client or server level will provide
what is effectively an unlimited extension of the system storage,
as the medium is removable. For large organisations that may
require more online data, the natural extension is to provide an
optical jukebox which places all the data effectively "near-line"
with retrieval times of 10-20 seconds if a disc needs to be moved
into a drive within the jukebox. Backup of this data can be either
to a second drive, or even to a DAT (Digital Audio Tape) or DLT
(Digital Linear Tape) system at the tertiary storage level. There
are many software solutions from companies such as Seagate, The
Cheyenne Division of Computer Associates and Q Star, to name a few,
that can transparently manage this data migration process right
through the primary, secondary and tertiary levels with user
parameters to controlling the data staging process. Interestingly,
the optical drives can, in many cases, use both re-writeable and
write-once media with such software, and these discs can be mixed
in a jukebox system so that more effective use of the technology
can be exploited depending on the user's application demands.Many
system administrators may well balk at the cost of some of these
solutions, but recent developments have made some optical devices
very affordable, even for the smaller organisation, with genuine
improvements in productivity and efficiency.Many large
organisations now implement optical technology to address specific
storage management issues. One of Germany's largest publishing
houses uses WORM discs to archive data in jukeboxes using Hyperdoc
(from Dr Materna), and once the data is no longer required for
access, the media is exported from the jukebox and can be used in a
single drive if required at a later date. Interestingly, there are
now many active and successful developers of software in Europe who
write applications to optimise the use of optical storage within
their data/image management systems. This naturally brings the
benefit of "localisation" as regards languages. Even at the low
end, PD (Phase Dual) drives which cost in the region of #300 are
used extensively, and in the Middle East a large bank has adopted
this technology to backup data on client PCs. The list of world
class organisations using optical storage is extensive, and whilst
a few may not have had the overall success levels expected, this
has usually been due to incorrectly identifying the application and
associated storage requirements.The headlines and advertisements in
the computer press have been full of CD Recordable as being
everyone's dream solution, but does it really offer all that seems
to be presented? The very idea of producing one's own CD-ROMs seems
attractive with many possible uses, but in general the answer must
be no. However, CD-R (Compact Disc Recordable) has some excellent
characteristics that make it suitable as a companion product for
existing storage solutions once the technical limitations are
really understood. Data can only be recorded in "sessions" where
the data must be kept flowing to the drive at a constant rate. Any
interruption in this data flow will cause errors and render the
disc unusable. Also, the medium is unprotected and, as such, is
susceptible to handling issues. Due to its sequential "session"
nature, there is no data verification "on the fly". The only way to
verify data is to read the disc after it has been recorded and if
any errors are present then another disc will have to be recorded.
But CD-R is a publishing medium, and a very good one. This is where
clients can have data distributed in an economical manner on a
medium that has wide industry standards at both the physical and
file level. Essentially, CD-R is an electronic version of the more
conventional, but cumbersome, laser printer or plotter. Apart from
the obvious applications, new areas are emerging such as publishing
intranet data where clients may not have Internet access. Ideally,
if CD-R is the medium of choice, then an application needs to sit
directly in front of the recorder to shield the customer from the
unfriendly nature of the technology.Software drivers which control
the storage devices play as important a role as the actual hardware
itself, so consideration needs to be given to the overall
integrated solution, not just the individual components.
Interestingly, in the case of CD-R, some software can more than
quadruple the expected recording time of a CD due to its data
preparation time! Of equal importance is the position within a
network of the intended storage device. Where jukeboxes are
concerned, it is usually beneficial to create a specific archive,
or backup server. This then removes the potential dangers of
introducing third party software drivers to an installed and
functioning system.With the correct match of appropriate technology
to the specific storage or application problem, the rewards will be
seen quickly both in improved productivity and service.
Compiled
by Geoff Marshall