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GFS Rotation
In traditional tape backup, there is a different tape for each backup generation. GFS (Grand Father Father Son) is the most popular tape rotation algorithm.
The following table shows you how you might create a GFS rotation Schedule. Each cell in this table refers to the name of the tape that should be used in this day.
| MON | TUE | WED | THU | FRI |
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| WEEK1 | | MON | TUE | WED | THU | WEEK2 | | MON | TUE | WED | THU | WEEK3 | | MON | TUE | WED | THU | WEEK4 | | MON | TUE | WED | THU | MONTH1 | | MON | TUE | WED | THU | WEEK1 | | MON | TUE | WED | THU | WEEK2 | | MON | TUE | WED | THU | WEEK3 | | MON | TUE | WED | THU | MONTH2 | |
Incremental or Differential |
Full |
The above example is for 2 months of backup history.
You will need 4 daily tapes marked Mon, Tue, Wed, and Thu; 4 weekly tapes marked Week1, Week2, Week3, and Week4, and two monthly tapes marked Month1, and Month2.
On weekdays (Mon -Thursday) use the appropriate Mon-Thu tape. Note if you are using incremental backups, and your backups are not too big, you may use a single tape for all those weekdays backups.
On weekends take full backup, use the appropriate weekly tape, unless its the last Friday of the month, where you should use one of the monthly tapes.
This idea can be expanded to keep longer history by adding more monthly tapes. So if you need one year of backup history use 12 monthly tapes, one for each month.
Relative Rev Backup can emulate this behavior on a single disk, without the hassle involved in rotating tens of tapes, using fast incremental forever, that can recover any file or folder instantly. This is in contrast to tape based backup that must recover the last full backup, followed by every incremental backup taken since.
Redundancy for the backup disk is supported.
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