A company’s backup schedule depends on whether the backup time or restore time is more important. For most companies, if time permits, a full backup should be performed every night. This means that the backup could take quite awhile and is dependent in the regular backup schedule.
If there are five files, for example, the backup will take the time required to read all five files and then write them to the backup media every day. Of course, a company will have more than five files, but for the interests of this article, we will keep the example.
If a company needs to have backups performed in a short period of time each night, it should implement an incremental backup schedule. The first day of the week, usually Sunday, a full backup is performed. Because the company data is not usually in use, the backup can be performed during the day and not cause any downtime by requiring files to be closed. Also, with large amounts of data, a longer period of time is required to perform a full backup of all files. This usually means that a full backup can only be done over the weekend.
Once a full backup is performed, all Archive attributes are turned off. Any files changed on Monday will have the Archive attributes turned back on. For example, if there are five files, and Files 2 and 5 are modified, the Archive attributes are turned back on. Because their Archive attributes have been turned on, these two files will be backed up during the Monday night backup. The Archive attributes will then be turned back off. Files 1, 3, and 4 will not be backed up because their Archive attributes are still turned off. There is no reason to back them up because they were backed up during the full backup on Sunday night and have not changed. The Archive attributes on files 1, 3 and 4 will not be changed after the backup.
On Tuesday files 3 and 5 are modified, which turns on their Archive attributes. During the Tuesday night backup, only files 3 and 5 are backed up and then their Archive attributes are turned off again. This continues throughout the week. The backup time will vary depending on the number of files that have been modified and the sizes of the changed files.
[tags]diana huggins,data protection,disaster planning & recovery,data loss,backup plan[/tags]