Four Questions For ERP Backup Rotation Methods

Posted by Gerry Poe

tandbergdata tape autoloader 01Tape-Autoloaders are ideal Backup Rotation Methods for your ERP data strategies such as, Grandfather-Father-Son (GFS)
Four Questions to Consider:

  1. What is your backup strategy in use today? 

  2. Do you know if it is properly executed and monitored? 

  3. Do you test your data recovery strategies to ensure your company can survive an attack or systems crash? 

  4. What events get reported/documented daily assuring these procedures are carried out?

Grand-Fathering scheme example:
GFS (grandfather, father, son) is a tape rotation strategy. GFS simplifies tape handling by organizing rotation into daily, weekly, and monthly backup tapes. You can also create Custom backup jobs that use the GFS strategy.

Why GFS?
IT administrators consider GFS one of the simplest and most effective tape rotation strategies.
The GFS tape rotation strategy provides several benefits:

  • It protects your data with a minimum number of tapes (normally, only one or two tapes are required to restore a file server), rotating some tapes and archiving others, so you can easily restore one file or an entire file server.
  • It reduces wear and tear on tapes and tape heads.
  • It provides a systematic approach to tape storage that ensures the highest possible protection for your data and gives you an easy way to locate stored files. This makes restoring directories and volumes fast and easy.
What is GFS?

The GFS tape rotation strategy is based on a 7-day schedule (Sunday through Saturday), in which you create at least one full backup each week. The rest of that week's backups can be full or differential. (A differential backup saves only the files that changed since the last full backup.)

Regardless of the number of full backups you create during the week, the LAST full backup of the week is considered the WEEKLY backup. You can reuse (recycle) the DAILY and WEEKLY backup tapes or take them offsite for permanent storage. For a discussion of when to reuse tapes, see Tape Recycling later in this document.

Here are some examples of weekly backup schedules:

None Diff* Diff Diff Diff FULL None
*Diff *Diff *Diff *Diff *Diff *Diff FULL

*Diff = Differential backup

In GFS terminology, the DAILY backup is the son and the FULL WEEKLY backup is the father. The last full backup of each month is considered the MONTHLY backup. In GFS terminology, it is the grandfather. The MONTHLY backup is always permanent--it cannot be reused. It's a good idea to store permanent tapes offsite.

The following is an example of a typical backup schedule.

1 2 3 4 5 6 7
None Diff* Diff Diff Diff F-WKLY** None
  Tape 1 Tape 2 Tape 3 Tape 4 Tape 5  
8 9 10 11 12 13 14
None Diff* Diff Diff Diff F-WKLY** None
  Tape 1 Tape 2 Tape 3 Tape 4 Tape 6  
15 16 17 18 19 20 21
None Diff* Diff Diff Diff F-WKLY** None
  Tape 1 Tape 2 Tape 3 Tape 4 Tape 7  
22 23 24 25 26 27 28
None Diff* Diff Diff Diff F-WKLY** None
  Tape 1 Tape 2 Tape 3 Tape 4 Tape 8  

* Diff=Differential backup


Tape Recycling

By default, backup recycles (reuses) DAILY tapes after the fourth daily backup. (In the previous example, notice how tapes 1 through 4 were reused each Monday through Thursday.) This four day cycle lets you restore a file to the state it was on any of those four specific days. By default, backup recycles WEEKLY backup tapes after the fifth full weekly backup.  You must ensure that each tape in the library is operational and can be restored, if necessary, at each level of recovery.

The previous example assumes that you've used the default tape recycle for a backup. In this case, a full year of backups would require 22 tapes: 4 DAILY, 5 WEEKLY, and 13 MONTHLY. Of course, this number can increase when tapes are retired at the end of their useful life, or if the tapes recycle-frequency is increased.  Calculating capacities and redundancies for a fault-tolerant recovery is mission critical.


Questions arise surrounding tape, disk, online backup-services and other methods for enterprise backups.  Experience tells us tape still reigns as the king of backup/recovery strategies.  Some reasons are for example; immediate 24X7 access by your IT department, bare-metal-recovery (allows you to reinstall from tape/disk backup to a new server/PC without loss or configuration issues). In the case of software and hardware, choices are overflowing.  Santa Claarita Consultants has stanard offerings with industry reliability leaders like, Symantec (Backup Exec family of products) and Tandberg Data (OEM for many brands) serving a wide range of capacity and platform needs.

For more information on backup software and hardware options, please drop us a note and we will help you design your optimal backup and recovery strategies. Please register for an on-site assessment of your enterprise and ERP technologies.


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Tags: ERP, Backup Methods, Tape Backup

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