Management of multiple generations of backup data

A control method for controlling a backup management device that manages multiple generations of backup data by rotating a plurality of rewriteable backup media while recording backup data onto the backup media according to a predetermined backup cycle, the control method comprising:

• (a) inputting a save period for which the backup data should be saved, the save period being individually set by the user for each of the multiple generations;
• (b) executing backup by means of selecting a predetermined overwrite-targeted backup medium on the basis of the backup cycle and the save period;
• (c) storing the save period in a save period storage;
• and
• (d) storing within a medium information storage, information regarding the backup medium and the time at which the backup data was stored in the backup, in association with one another;
• wherein the selecting of the overwrite-targeted backup medium includes refering to the save period storage and the medium information storage, and when generation n (n is a natural number) backup data moves to a save period (m+1) one period older than a save period m to which the generation n belongs, and deciding whether first generation backup data is overwriteable onto the backup medium in which the backup data was stored;
• and
• wherein the deciding compares a first predetermined time interval until generation (n−1) backup data one newer than the generation n backup data moves to the save period (m+1) with a second predetermined time interval until the generation (n+1) backup data leaves the save period (m+1), and when the first predetermined time interval is equal to or shorter than the second predetermined time interval, decides that the backup medium storing the generation n backup data is overwriteable.

A control method for controlling a backup management device that manages multiple generations of backup data by storing backup data onto any of a plurality of rewriteable backup media, according to a predetermined backup cycle, the control method comprising:

• (a) inputting a save period for which the backup data should be saved, the save period being individually set by the user for each of the multiple generations;
• (b) storing the save period in a save period storage;
• (c) storing in a medium information storage, information regarding the backup medium and the time at which the backup data was stored on the backup medium, in association with one another;
• (d) at each backup cycle, referring to the save period storage and the medium information, and when generation n (n is a natural number) backup data moves to a save period (m+1) one period older than a save period m to which the generation n belongs, deciding whether first generation backup data is overwriteable onto the backup medium in which the backup data was stored;
• (e) when the decision result is that overwriting is possible, executing first generation backup by overwriting the backup medium, and when the decision result is that overwriting is not possible, preparing a new backup medium and executing first generation backup, or issuing a warning to the user;
• and
• wherein the deciding compares a first predetermined time interval until generation (n−1) backup data one newer than the generation n backup data moves to the save period (m+1) with a second predetermined time interval until the generation (n+1) backup data leaves the save period (m+1), and when the first predetermined time interval is equal to or shorter than the second predetermined time interval, deciding that the backup medium storing the generation n backup data is overwriteable.

A computer program product for control of a backup management device that manages multiple generations of backup data by rotating a plurality of rewriteable backup media while recording backup data onto the backup media according to a predetermined backup cycle, the computer program product comprising:

• a computer readable medium;
• a first program code that acquires a save period for which the backup data should be saved, the save period being individually set by the user for each of the multiple generations;
• a second program code that selects a predetermined overwrite-targeted backup medium on the basis of the backup cycle and the save period;
• a third program code that executes first generation backup by overwriting the selected overwrite-targeted backup medium, and when a decision is that overwriting is not possible, prepares a new backup medium and executes first generation backup, or issues a warning to the user,
• a fourth program code that stores the save period in a save period storage;
• a fifth program code that stores, in a medium information storage, information regarding the backup medium and the time at which the backup data was stored in the backup, in association with one another;
• wherein each of the program codes is stored on the computer readable medium;
• wherein the decision refers to the save period storage and the medium information storage, and when generation n (n is a natural number) backup data moves to a save period (m+1) one period older than a save period m to which the generation n belongs, decides whether first generation backup data is overwriteable onto the backup medium in which the backup data was stored;
• and
• wherein the decision compares a first predetermined time interval until generation (n−1) backup data one newer than the generation n backup data moves to the save period (m+1) with a second predetermined time interval until the generation (n+1) backup data leaves the save period (m+1), and when the first predetermined time interval is equal to or shorter than the second predetermined time interval, decides that the backup medium storing the generation n backup data is overwriteable.