10. Preservation There are two main aspects to ensuring the long-term preservation of digital audio data. The first conerns the life-span of digital storage media such as computer hard-disk drives and removable media such as CDs. The second concerns sound file formats and obsolescence. 10.1. Storage media Digital information held on computer hard-disks is not permanent. There are many factors which can result in the loss of data; these include mechanical failure (increasingly likely with age), electronic corruption (such as may be caused by errors in computer programmes, malicious viruses etc), and faults in magnetic or optical media (the material of the disk surface itself which stores the information). It is vital to take adequate steps to guard against such loss, both in the resource creation process and in the long term (i.e. beyond the life of the project, if the resource is to remain in place). Fortunately, backing up fairly small amounts of data is now relatively straightforward, using extra hard-disks and removable media such as writable CDs. Specialist high-capacity long-term storage systems are also available, though they can be relatively costly. The key to successful preservation is to have a strategy for backing up on a regular basis both during the creation process and once the resource is up and running. As any data is created, at least one backup copy should be made. This backup should be logged and stored safely. Once the creation process is complete, a long term strategy should take over. Such a strategy could be based on the following rules of thumb: If data in the resource changes often, backup often, and maybe make incremental backups rather than complete backups. How often will depend on the frequency and extent of the changes made. If data rarely or never changes, and the integrity of previous backups is reliable, then it makes sense to backup whenever changes are made or decide on some regular period for backing up. Where a resource contains critical data it is advisable to seek specialist advice on preservation. PADS will hold a preservation copy of your data too, but this should not be relied upon as delivering the data to users is your responsibility; in order to maintain service it is best to have a way of backing up and restoring your own data efficiently. 10.2. Audio file formats The other important aspect to consider is not just protection of the data itself, but also support for the format in which it is stored. This relates to the possible lifetime of sound file formats, and though this is not really currently an issue, it may be in future; it is important to stay informed about developments in audio file storage. For instance, the 'wav' and 'aiff' formats are very common file formats today, and there is a huge amount of software that will deal with these files and play them back to users. They have been around for some years, and are likely to remain for the foreseeable future. But this may not always be the case. Though the standards will remain, there may be a time when they are superceded and other types of storage become more widespread; in this case some decision may need to be made about whether to convert files to more modern formats. Similarly, whilst the 'mpeg3' format is very common on the internet just now, in future it may well be superceded by other higher performance methods for delivering audio. A similar consideration has to be made regarding backup media, as storage capacities of media are likely to increase (as they have done dramatically in recent years), and the media themselves are likely to be displaced by newer high capacity systems. This is a continuous process in the computing field and it is important for resource creators and owners to stay in touch with new developments. Otherwise you may well be faced with having large quantities of data in essentially obsolete formats and media. Top of Page
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