If you do not need to minimize time requirements and the number of media that is used for backups, you can do full backups every day. However, this backup method is not realistic for most sites, so incremental backups are used most often. In this case, you should back up your site enough to so that you can restore files from the last four weeks. This schedule requires at least four sets of tapes, one set for each week. You would then reuse the tapes each month. In addition, you should archive the monthly backups for at least a year. Then, keep yearly backups for a number of years.