We store all our important data on hard
disks and DVDs which last only for 10 years. Thanks to new technologies, there
are many types of robust digital storage media, but not many people know about
them.
By
the end of 2012 there will be 2,500,000,000,000,000,000,000 bytes of data
stored on various forms of media - an amount that the human mind can barely
comprehend
By the end of 2012 there will be
2,500,000,000,000,000,000,000 bytes (or 2,500 Exabytes) of data stored on various
forms of media - an amount that the human mind can barely comprehend. More
incomprehensible is the fact that this data could easily disappear within five
years because the hard disks on which most of it lies cannot last very long and
might not be replaced in time. In addition, DVDs are still the number one
archiving medium for home users, according to a survey by US Market Research.
About 43 percent of people use a data storage medium which is much less secure
and durable than even ordinary hard disks. The result is paradoxical and
potentially dangerous: we save our important documents, personal photos and
videos on storage media which we really shouldn't trust. We in fact seem to
have a false sense that our digital treasures are securely archived and can be
accessed whenever required. Secure backups would involve regular maintenance
and auditing on a PC, which many users avoid. Regular backup maintenance
involves regularly moving your data onto new data storage devices and mediums,
because the old ones could break down some day and there's no way to know
exactly when.
Thankfully, there are several relatively
reasonable solutions for long-term archiving of important documents: the most
appropriate ones for ordinary home and office users include two types of
writable discs and a specially prepared type of flash memory. All these
guarantee a data lifetime of 100 to 1,000 years—whether the technology to read
the data on them will exist for that long is another matter altogether. Apart
from these, other promising technologies can also help ensure reliable
long-term data storage.
Digital data has an expiry date
There are various reasons why our data
storage media are not designed for long-term storage. Hard disks are sensitive
to environmental influences such as moisture and heat; they cannot even endure
vibrations and jolts. Flash hard disks do not require any sensitive mechanism
but their flash cells don't last eternally. They normally wear out in daily use
after 10,000 write/delete cycles. But even if one does nothing it loses its
charge - it lasts only a couple of years.
Other considerations also play a role in
case of long-term archiving on hard disks, such as corrosion which affects all
electronic circuitry. The NTFS file system on which we store almost everything
these days was developed by Microsoft. It is not an open standard and might not
outlive Microsoft itself. Who can guarantee that Windows will live on for the
next 100 years? The same applies for cloud-based storage. No one can predict
whether Google or Amazon will still be operational in 20 years. Against that,
burnt discs have the advantage that read and write processes are completely
standardised. In case of an extreme emergency, the data can also be read and
reconstructed using a powerful microscope.
So do CDs and DVDs have a future when it
comes to long-term archiving? Not with the blanks that one can buy in stores.
They are often of an inferior quality; the result of long-running price
struggles. If you have archived your important photos and videos on them more
than three years ago, you might experience an unpleasant surprise when you next
try to use that disc. The data that people believe to be secure is likely to
have disappeared —literally. The further complication is that predicting when a
disc is going to break down is as good as impossible. Even blank discs of well-
known brands are not a guarantee of a long life. Blank disc of the same brand
and from the same spindle can last for as little as 5 years or as long as DO
years, that too under the same storage conditions. Data security thus becomes a
game of luck.
Why blank DVDs don’t last very long
Material Weaknesses
Three factors reduce the lifetime of a DVD:
Exposure to light weakens the organic dye, the metal layer oxidises, and the
polycarbonate does not respond well to high temperatures.
Why
blank DVDs don’t last very long
Quality variations
An age test conducted in France has shown
that discs from the same brand also break down at different rates. The test was
executed according to the ECMA 379 standard at a temperature of 80 °C and
humidity of 85%.
Data storage media lasts this long
Digital data storage media doesn't really
store data reliably for the long term.
M-disc: data set in stone
The M-disc stores your data in a layer
similar to a stone. The manufacturer guarantees a durability of 1,000 years.
The M-disc by a company called Millenniata
resolves the biggest weakness of normal blank DVDs whose durability depends on
the quality of the organic dye in which the laser burns information, and also
on the quality of the metals in the reflective layer. When reading data, light
is reflected from the metallic layer at the points in which the laser has burnt
into the dye. There is a risk of oxidation of the reflection layer which
normally consists of aluminum or silver. Some manufacturers such as Verbatim
therefore use gold or an alloy of silver and gold for discs which are supposed
to last particularly long. However, only the smaller problem is solved, and the
dye, which is the actual weakness of a disc with respect to environmental
influences, is still just as weak. Exposure to strong sunlight, high humidity
and high temperature can simply dissolve the dye, and the data disappears with
it.
The data is not burnt onto a dye layer on
the M-disc but is instead burnt onto an inorganic layer of rock-like material
according to the information provided by the manufacturer. This inorganic layer
is made of metals and semi-metals, silicon dioxide and carbon. The manufacture
does not specify the exact composition of its material. Another difference to
burnt DVDs: the necessary laser power is considerably higher and discs are
burnt at a maximum speed of 4x. In the process, the material dissolves at the
specific points at which the laser hits the surface. It also burns holes in the
data layer and a metallic reflection layer is thus unnecessary. On cooling off,
the material forms a polycrystalline structure at the edges which is not unlike
rocks. From that point of view, the M-disc is actually capable of storing your
data in a material similar to stone.
