Backup Strategy
Often one needs an accidentally deleted or spoiled data file. Normally, this loss is recognized only after a few days and the already defect data file has been safeguarded with the last backup. Hence the backup should always be effected following the generation principle.
Which data files do I have to consider for a Backup?
Of course, it makes no sense to safeguard data files, which are stored on CD/DVD anyway, Windows itself and all programs which are available on their own media.
Variable Data
For a backup all the data are important, which are written by oneself, for example texts, pictures, e-mails, databases, accounting data, R&D- projects, etc., and therefore are of high material and immaterial value. In addition, according to law, a lot of data are to be filed during several years.
The data backup is very alleviated, if these relevant data (letters, templates, databases etc) are situated beneath a folder (e.g. own data sets). Thus, the backup procedure becomes simple, reliable and translucent.
Daily data backup according to the generation principle
Basically, the generation principle is not bound to a certain chronological rhythm, the easiest method consists in arrangement of three backup categories – e.g. daily, weekly or per month. In this case a daily backup is generated.. These son-backups are rotating every week (i.e. after one week, the first son-backup becomes overwritten), the father-backups, which are each overwritten-by the end of a week, are rotating every month (i.e. after one month, the first father-backup becomes overwritten) and the grandfather-backups, which are each overwritten by the end of a month are rotating every year (after one year, the grandfather-backup gets overwritten).
For a backup in line with a five days week one would need a storage capacity for:
- Four son-backups (Monday to Thursday; Friday is a father-backup)
- Three father-backups (for the first three Fridays of a month, the fourth and last Friday can be stored as a grandfather-backup)
- Twelve grandfather-backups (for the last day in every month)
There are not required five Friday-backups, because, if there are five Fridays a month, the Friday is the last weekday of the month. Consequently there is a grandfather-backup used for storage and NOT a father-(Friday) backup.
Following this principle, one could always access a backup of
- Each of the last four workdays (son-backups)
- Each of the last four Fridays (father-backups)
- Each of the last twelve ends of month (grandfather-backups)
There is the possibility of either incremental or differential backup to reduce the requirement of memory space.
Incremental backup
With an incremental backup there are only these files safeguarded, which have been written or changed since the last backup of the type Normal or Incremental. If you use a combination of normal and incremental backups, you need for reconstitution of your data on the one hand the last normal storage record, and on the other hand, all incremental storage records.
Differential backup
With a differential backup there are all these files safeguarded, which have been written, resp. changed since the first backup of the type Differential. I you carry out a differential backup, it is required for reconstitution of files and folders, that the first full-backup same as the last differential backup are available.
This method is very similar to the incremental backup and is also carried out in changeover with complete backups. At this, on Monday these data are safeguarded, which have changed on Monday, on Tuesday the files of Monday and Tuesday etc., consequently all data since the last full-backup. Advantage: You need the last full-backup and the last differential backup just at the time when you want to reconstitute your original database.
