Tape Drives - Notes 2

This article (not in its entirety) was taken from http://www.aplawrence.com/Unixart/unix_ba.html

Full backup means backing up everything on the system.

A copy backup copies all selected files but does not mark each file as having been backed up (in other words, the archive attribute is not cleared). Copying is useful if you want to back up files between normal and incremental backups because copying does not affect these other backup operations.

An incremental backup backs up only those files created or changed since the last normal or incremental backup. It marks files as having been backed up (in other words, the archive attribute is cleared). If you use a combination of normal and incremental backups, you will need to have the last normal backup set as well as all incremental backup sets in order to restore your data.

Here the backup is taken for the files that have changed since last backup or modified after certain date or time. It saves lot of time. But while restoration Full backup is to be restored first followed by all the incremental Backups. Incremental backups are of ten levels. i.e. 0 to 9

Level 0 – is the full backup of the whole system.

Level 1 -- is the backup of the data that are changed after the Level 0 Backup.

Level 2- 9 – is the backup of the data that are changed after the previous level backup.

A differential backup copies files created or changed since the last normal or incremental backup. It does not mark files as having been backed up (in other words, the archive attribute is not cleared). If you are performing a combination of normal and differential backups, restoring files and folders requires that you have the last normal as well as the last differential backup.