National Library of Wales chooses optical disk media for digital archive

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National Library of Wales chooses optical disk media for digital archive

Antony Adshead, UK bureau chief, storage
The National Library of Wales has chosen Plasmon UDO (Ultra Density Optical) disk over tape for long-term storage of its national archives. UDO disk won out in the library's quest for longevity of data storage, relatively quick access for library users and ease of management compared to tape.

The National Library holds the largest collection of artefacts related to Wales, including books, periodicals, newspapers, manuscripts, maps, paintings, drawings and prints, photographs, sound files and moving images. The library offers free access to its collection on-site and remotely through its rapidly growing electronic archive. Since 1998 the National Library has been engaged in a project to digitise its archive, with the £80,000 project to transfer data to the Plasmon UDO the latest phase to be accomplished.

Tape might seem very compact, but we're always aware of issues around its reliability and of the need to refresh it every five years.
Einion Gruffudd
senior systems analystNational Library of Wales
As part of the project, as many as 2,000 documents are being scanned each day, ranging in size from 1 MB to 50 MB. The Library's digital archive, currently at 8 TB, is currently growing at a rate of 2 to 3 TB each year. As it is the national archive, the Library must maintain its records indefinitely, so its objective was to maintain an accessible archive while also to minimise the number of future migrations to save time and money and lower the risk of data loss or corruption.

The National Library's senior systems analyst, Einion Gruffudd, has been aware of the shortcomings of tape for long-term retention. "We've got lots of archiving projects going on and we're trying to keep up with demand," he said. "Storing it all is the main problem. Tape might seem very compact, but we're always aware of the issues of storing it that way – of its reliability and of the need to refresh it every five years. Tape is also a problem for the user in that it takes several minutes to access the data. So we had the dilemma of how to plan for the future, especially as the volume [of data] is growing."

After dismissing tape, Grufudd's team looked at CD and DVD jukebox products, but these also failed to meet the Library's requirements. His team finally opted for Enterprise Plasmon G438 UDO library, and has since migrated to the model G638, which is controlled by Quantum Corp.'s Amass near-line archiving software running on a Sun server.

The Plasmon library offers a maximum of 38 TB of storage on 638 UDO disks. UDO is a 5.25-inch rewritable 60 GB optical disk format, although 120 GB and 240 GB versions are planned. It is in concept very similar to rewritable CD or DVDs but is written to a higher density and is more durable, with long-term – 50-year or more -- storage applications in mind.

The National Library scans initially to magnetic RAID disk and then, via a quality control process, transfers files to UDO disk for rapid user access, plus three more instances of tape – on- and off-site -- for redundancy.

Grufudd said the choice of the Plasmon UDO library was a no-brainer. "We wanted to get away from tape and looked at CDs and DVDs with jukebox devices but there was no comparison really, as they were not as durable and access was far slower. We were not impressed with the capacity and physical footprint either."

The choice of UDO has allowed the National Library to extend the life of data on that media to 50 years or more while speeding up access time to the data, said Grufudd.

"The immediate benefit is that the customer is happier with the access they have to our files," said Grufudd. "And from the management point of view we have split the risk a bit between tape and optical, so we are much more confident now. The data we have is very valuable and in some cases irreplaceable, with some, for example, photos, coming to the end of their physical life."


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