Backup protection of content

Any digital audio project, regardless how small, represents an investment of time, and because the creation of digital audio from analog sources like LPs and cassettes must be done in real time--a half hour of music requires at least a half hour for encoding--a project that relies heavily on analog sources requires a significant investment in time. Protecting this investment, on the other hand, requires little time and expense, especially when compared to the work that would be required to recreate the project.

The most time-intensive step in the encoding process is the creation of the uncompressed audio file. If this file is preserved, the time spent creating it will not need to be lost in the event of a natural disaster, the malicious vandalism of a hacker, or something more innocuous--like the migration to a different format for audio streaming.

Compressed audio files, on the other hand, are often not backed up, for two good reasons. First, the time required to recreate a compressed file is relatively insignificant (so long as you have retained the source CD or uncompressed audio file) and as microprocessors grow faster, that time becomes increasingly negligible. Second, as network speeds increase and compression technologies become more sophisticated, it is inevitable that an audio project will eventually migrate to a new compression format for delivery, in which case the compressed files will eventually need to be recreated.

Judging from the responses to the survey, the majority of libraries do not create and maintain independent archival copies of audio files--compressed or uncompressed--for their digital audio-reserve services. Less than one third of the libraries routinely archive the source files. This does not mean that most libraries routinely destroy source files once they have been used. Often they will reside on the encoding computer, but no backup is kept beyond this initial copy, and if a disaster were to strike the encoding computer, the work would be lost.

Even libraries who do routinely maintain archival copies of uncompressed files choose not to back up uncompressed files ripped from compact discs. The compact discs themselves can serve as a backup, and if the compressed files created from a particular CD are lost--or need to be recreated in at a different bitrate or in a different format--the collection's copy of the source CD can be put into service. Because replacement files can be digitized from a compact disc at a rate much faster than real time, backing up uncompressed source files for compact discs becomes a practice that consumes time and storage space when very little risk is being assumed.

When backing up data, regardless of the medium, it is important to keep the backup copies separate--physically and virtually--from the data being protected. There are three back up methods reported in the survey:

Remote server. Files are copied to a remote server, which itself is routinely backed up by IT personnel. This method is simple and quick, since it places the bulk of responsibility on the administrator of the server, and the library simply needs to make sure that files are copied to the server as soon as they are created.

Recordable discs. Files are copied to recordable compact discs (CD-Rs) or recordable DVDs. This method has the advantage of keeping the archival copies easily accessible and under the full control of the library, but it also requires the library to maintain a regular back up schedule and devise a routine for organizing and storing the CD-Rs.

External hard drive. Files are copied to an external hard drive, typically a USB drive that can attached easily to the computer for backup and then removed for storage in a safe place. The advantages are ease and speed of the backup; the disadvantage is relying on a storage device that itself might be subject to failure.

With backups, redundancy is important. Better to set up two redundant backup methods than to rely on one whose failure would spell disaster.