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Archive for February, 2022

CD/DVD Degradation

Tuesday, February 8th, 2022

istock_000005139238xsmallUnfortunately CD’s and DVD’s are not built to last. Degradation in optical media refers to this decline in the physical quality of CDs, DVDs and Blu-rays over time.  There are two main factors that this eventuality can be attributed to; material and environment.

Material factors:

-Disc Format.  A CD-ROM has a different composition than a CD-RW, therefore they deteriorate at different rates.

-The manufacturer. There are variations in the dyes, plastics and alloys used, which in turn cause divergences in quality between brands.

-The equipment used to read or write the disc itself.

Environmental factor:

-Exposure to high temperature. Increase in heat speeds the degradation process by breaking down the recording layers of discs that utilise organic dye compounds.

– Extreme humidity. Moisture can seep into the cracks and scratches of a disc which could foster the growth of bacteria and/or mould; this can affect how effective the laser’s ability is to read the disc.

– Regular contact with UV. Direct sunlight accelerates the rate of aging of a disc. It renders the disc ineffective by altering the appearance of the recording layers.

Dust, dirt and air pollution. Any foreign particles that accumulate on the disc surface and in cracks or scratches can damage the disc and cloud reading and recording.

Inappropriate handling or storage also contributes to an increased deterioration process of CDs, DVDs and Blu-rays.

As discs have a limited shelf life, no matter how well they are treated by the user, degradation can only be controlled to a certain extent. The core recording layers of a disc will naturally break down before the outer plastic takes away layers. The outer deterioration of the polycarbonate incurs damage mainly from rough handling, and is therefore not considered when measuring the disc’s overall shelf life.

Consequently, the lifespan of CDs, DVDs and Blu-rays contain a range of testing measurements and can be conservatively estimated, with some compact discs tending to outlast DVD formats:

  • Unrecorded CD-R and CD-RW: 5-10 years
  • Recorded CD-R: 50-200 years
  • Recorded CD-RW: 20-100 years
  • Recorded DVD-R: 30-100 years
  • Recorded DVD-RW: up to 30 years
  • Recorded BD-R and BD-RE: 30-200 years

Since Blu-ray is a newer technology, it should be noted that further testing and calculations are required to more accurately narrow a lifespan.

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Plasmon’s UDO and Blu -Ray: top shelf technologies in optical data storage

Tuesday, February 1st, 2022
Phase Change technology of writing data optimises the write time and allows for more efficient data storage

Phase Change technology of writing data optimises the write time and allows for more efficient data storage

It’s commonly known that technology used for storage purposes must be characterized by its huge data capacity in order to make the whole enterprise economically viable. Using this one criterion only, there are only two suitable technologies left: UDO (Ulttra Density Optical) and Blu-Ray disc.

Since they offer similar benefits in general, the question which technology has bigger chances to stay on the market will be determined by the investment costs of its implementation and by the size of the existing installed base. The answer may be obvious already…

The UDO technology was developed by Plasmon as a replacement for MO (Magneto Optical) technology in the beginning of this century with long term archiving in mind. UDO -1 holds 30 GB per disc and the newly developed UDO – 2 can hold up to 60 GB per disc, 30 GB per each side. It’s double sided which requires a rotation mechanism to turn the media over. It uses Phase Change technology to write data. The data can be read/written at 8 MG/sec. using Reed Solomon error correction.  The laser is applied at two heat levels what provides faster write times, higher storage densities and higher life cycle (the number of writes that a spot can whitstand at its full capacity). Its estimated archive life exceeds 50 years. The medium is housed in a rugged dust proof caddy.

Unfortunately, high costs of UDO’s implementation and proprietary issues, plus a few extra drawbacks, like the fact that a special software is required to read UDO media or the lack of a native format, made Plasmon went into administration at the end of 2008. The technology was sold and it’s now manufactured by Alliance Storage Technologies. Similar fate was shared by InPhase Technology, which also attempted to develop holographic storage and failed due to same reasons.

With UDO’s experience in mind, it’s now clear why it is Blu – Ray that prevails as a widely used archiving medium. It is supported by hundreds of companies globally and shares many of the features with UDO, like high reliability and low maintenance costs. Its main benefit over UDO is huge installed base and the universal format of the written data. Of course, Blu- Ray ‘naturally’ evolved from CD and DVD which makes it backward compatible. It is also not as ruggedised as UDO and is housed in slim jukeboxes (some marketing specialists dare to label them even as ‘sexy’).

And what is the moral of that story? Maybe something like: no matter how advanced and sophisticated the technologie is, it’s always up to the market to determine its overall life span by verifying all its aspects  with scrutiny.

Republished by Blog Post Promoter


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