One very specific aspect of digital Preservation is ensuring that the contents of physical disks can be accessed in the future. I found I had four types of challenges in this area: 1) old 5.25 and 3.5 disks that I no longer have the equipment to read; 2) a CD with a protected video on it that couldn’t be copied; 3) two CDs with protected data on them that couldn’t be copied; and 4) about 120 CDs and DVDs containing backups taken over a 20 year period. My experiences with each of these challenges are described below:
1) Old 5.25 and 3.5 disks: I looked around the net for services that read old disks and I eventually decided to go with LuxSoft after making a quick phone call to reassure myself that this was a bona fide operation and the price would be acceptable. I duly followed the instructions on the website to number and wrap each disk, before dispatching a package of 17 disks in all (14 x 5.25, 2 x 3.5, 1 x CD). Within a week I’d received a zip file by email of the contents of those disks that had been read and an invoice for what I consider to be a very reasonable £51.50. The two 3.5 disks and 1 CD presented no problems and I was provided with the contents. The 5.25 disks included eight which had been produced on Apple II computers in the mid 1980s and these LuxSoft had been unable to read. I was advised that there are services around that can deal with such disks but that they are very expensive; and that perhaps my best bet would be to ask the people at Bletchley Park (of Enigma fame) who apparently maintain lot of old machines and might be willing to help. However, since these disks were not part of my PAWDOC collection and I didn’t believe there was anything particularly special on them, I decided to do nothing further with them and consigned them to the loft with a note attached saying they could be used for displays etc. or destroyed. Of the six 5.25 disks that were read, most of the material was either in formats which could be read by Notepad or Excel, or in a format that LuxSoft had been able to convert to MS Word, and this was sufficient for me to establish that there was nothing of great import on them. However, one of 5.25 disks (dating from 1990), contained a ReadMe file explaining that the other three files were self-extracting zip files – one to run a communication package called TEAMterm; one to run a TEAMterm tutorial; and one to produce the TEAMterm manual. Since this particular disk was part of the PAWDOC collection (none of the other 5.25 disks were), I asked LuxSoft to do further work to actually run the self-extracting zips and to provide me with whatever contents and screen shots that could be obtained. I was duly provided with about 30 files which included the manual in Word format and several screen shots giving an idea of what the programme was like when it was running. LuxSoft charged a further £25 for this additional piece of work, and I was very pleased with the help I’d been given and the amount I’d been charged.
2) CD with Protected Video files: This CD contained files in VOB format and had been produced for me from the original VHS tape back in 2010. The inbuilt protection prevented me from copying them onto my laptop and converting them to an MP4 file. After searching the net, I found a company called Digital Converters based in the outbuildings of Newby Hall in North Yorkshire which charged a flat rate of £10.99 + postage to convert a VHS tape and to provide the resulting MP4 file in the cloud ready to be downloaded. It worked like a dream: I created the order online, paid the money, sent the tape off, and a few days later I downloaded my mp4 file.
3) CDs with protected data: I’d been advised that one way to preserve the contents of disks is to create an image of them – a sector-by-sector copy of the source medium stored in a single file in ISO image file format. This seemed to be the best way to preserve these two application installation disks which had resisted all my attempts to copy and zip their contents. After reading reviews on the net, I decided to use the AnyBurn software which is free and which is portable (i.e. it doesn’t need to be installed on your machine – you just double click it when you want to use it). This proved extremely easy to use and it duly produced image files of the two CDs in question in the space of a few minutes.
4) Backup CDs and DVDs: The files on these disks were all accessible, so I had a choice of either creating zip files or creating ISO image files. I chose to create zips for two reasons: first, I wanted to minimise the size of the resulting file and I believe that the ISO format is uncompressed; and, second, on some of the disks I only needed to preserve part of the contents and I wasn’t sure if that can be done when creating a disk image.
Having been through each of these 4 exercises, there are some general conclusions that can be drawn:
- The way to preserve disks is to copy their contents onto other types of computer storage.
- The file size capacities of old disk formats are much smaller than the capacities of contemporary computer storage formats. For example, none of the 5.25 disks contained files totalling more than 2 Mb; the CDs contain up to about 700 Mb; and even the DVDs contain no more than 4.7 Gb. In an era where 1Tb hard disks are commonplace, these file sizes aren’t a problem.
- There are three stages in preserving disk contents; first, just getting the contents from the disk onto other storage technology; second, being able to read the files; and third, should the contents include executables, being able to actually run the programs.
- The decision about whether you want to achieve stages 2 or 3 will depend on whether you think the contents and what they will be used for, merit the extra effort and cost involved. In the case of the 5.25 disk containing TEAMterm software described above, providing a capability to run the application would have involved finding an emulator to run on my current platform and getting the programme to work on it. I judged that to be not worth the effort for the purpose that the disk’s contents were being preserved for (to be a record of the artefacts received by an individual working through that stage of the development of computer technology).