Method and apparatus for performing retroactive backups in a computer system

A method of retroactively backing up files stored in a computer system, comprising:

• establishing one or more backup levels, each backup level having an associated selection criteria for performing a backup at the backup level, the associated selection criteria specifying a retroactive backup date corresponding to a date of a previous backup;
• associating file attributes with each file;
• scheduling backups to be performed at the established backup levels;
• detecting that a backup is scheduled to occur;
• determining the established level of the scheduled backup;
• ascertaining which of the files are eligible for backup, the eligibility being defined by the established level of the scheduled backup and the retroactive backup date specified by the selection criteria;
• selecting for backup ones of the files having a date of last modification occurring between the date of a last backup having an established level lower than the established level of the scheduled backup or equal to the established level of the scheduled backup if the established level is the lowest established level and the specified retroactive backup date;
• creating a new save set at the established scheduled backup level, the new save set including copies of the selected files;
• and
• timestamping the new save set with the specified retroactive backup date.

An apparatus for retroactively backing up files stored in a computer system, comprising:

• a backup schedule employing one or more backup levels, each backup level having selection criteria associated therewith, the associated selection criteria operating to define a point through which the backup at the backup level with which the selection criteria is associated is taken;
• at least one save set, each save set storing one or more files backed up in accordance with the backup schedule, each save set and file having attributes associated therewith;
• means for detecting that a backup is scheduled to occur;
• means for determining the established level of the scheduled backup;
• means for identifying any save sets created since a last lower level save set or last same level save set if the established level of the scheduled backup is the lowest level;
• means for reading the selection criteria associated with the established level of the scheduled backup;
• means for ascertaining which of the identified save sets has files eligible for backup by testing the attributes associated with the files against the selection criteria;
• and
• means, responsive to the means for ascertaining, for backing up the eligible files, the means for backing up the eligible files thereby creating a new save set at the scheduled backup level, the new save set being timestamped with a date corresponding to the backup date of the most recent one of the identified save sets having files eligible for backup.