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2017-02-06 | Optical discs for data storage. The potential of the Blu-Ray

Over the past few years, with widespread of massive storage on hard drives (mechanical and solid state disks), USB flash drives and the cloud, it seemed that the optical media had been relegated to a marginal role. It also contributed to this the time it was necessary to invest in recording them, their limited capacity for standards of the second decade of the 21st century (700 MB on a CD and 4.7 GB on a DVD) and the decomposition of the internal organic compounds that safeguard the information. In 2002 Sony and Panasonic launched the Blu-Ray, a new disc format that allowed to accommodate up to 25GB. Unlike the pre-existing formats, it kept the data in an inorganic layer more resistant to the passage of time and, especially, to light. The arrival of this new technology made the pioneers in adopting it face the cost of the discs and the burners that, in both cases, were very high.

Since then, and fortunately for the average user, prices have dropped significantly and this has allowed the Blu-Ray to be used for long-term data archiving in homes and small businesses. With a quick search in the main electronics retailers, recording units are sold for less than 100 euros and discs for less than 10, although this depends on the capacity. This last feature has also evolved significantly with the appearance of new formats with more than one layer that can hold up to 50 (BD-R DL) or 100 GB (BDXL TL) (only including those that can be recorded outside industrial facilities), which ultimately allows redundant copies of large amounts of data for a reasonable price.

Recordable side of a Blu-Ray disc

Data centers seem to support the theory that Blu-Ray can be a viable storage medium for cold data (which does not need to be changed frequently, such as photographs). The best example in this sense in Facebook, whose engineers have developed units capable of handling 10,000 Blu-Rays of 100 GB each, which raised the total capacity to 1,000 TB, that is, 1 Petabyte. The concept has been interesting for Sony who has bought the idea to develop it on a large scale under the name of "Everspan", promising data retention for 100 years. Panasonic has followed the steps to the previous one with "Freeze-Ray".

Domestic users benefit from these advances through social networks, also with the use of the cloud, being Amazon Glacier, Google Nearline or Coldline the main examples. Obviously, we can also do it without intermediaries recording our own Blu-Rays and keeping them in regular environmental conditions. Thus, while recalling the recent past of the optical discs at the beginning of the article, it seemed that they were bound to disappear, their future is indeed promising. For instance, the two Japanese giants mentioned above, have presented a new format "Archival Disc" that initially has 300 GB of capacity, with future generations of up to 1 TB.

Curiously, although also worryingly, the preservation of digital data has not managed to overcome the resistance of conventional methods such as stone engraving. This comparison, which may be irrelevant, is of great importance when, for example, it is desired to preserve the knowledge of humanity, which has generated more data in the last three decades than in the rest of its history. Within this vast array, information on radioactive waste that should be available for generations for controlled treatment is especially sensitive.

Before concluding, I recommend watching the documentary "The end of memory?", where some of the topics collected in this article are reviewed and others related are referred.

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