Safe to Delete Previous Incremental BUs?

jeffb99

I'm using the Standard version (7.1.1).  Is it safe to delete previous incremental backups to save space and keep only the Full and most recent Incremental?  Or does Restore need ALL incrementals if the folder/files are lost and need to be restored to their most recent version?

This question has probably been asked before somewhere but I can't find the answer.  Thanks.

--Jeff

jeffb99

I think I found the answer to this in the FAQ.   "If any one of the incremental image files in the sequence is damaged or missing, the subsequent image files will be invalid."   BUT...Is this also true for Differential BUs if I upgrade to the Pro version?? 

admin

@Jeffb99, A Full Backup must exist as the start point of a series of incremental backups. A typical set would be in time sequence. All the image files in an incremental backup series share a sequential relationship and data can be recovered to the state when any Incremental Backup was done. If any one of the incremental image files in the sequence is damaged or missing, then subsequent image files will be invalid.
For example, the backup versins are: Full0--Inc1--Inc2--Inc3...Full1--Inc4--Inc 5.. You can select any backup version to restore. It will restore to the status when the backup version is created.
If the Full0 is damaged or deleted, Inc1,Inc2 and Inc3 are valid. Of course, Full1--Inc4--Inc 5 is another group, which isn't affected by the first group.
If the Inc2 is damaged, Inc3 is valid. But, Full0 and Inc1 still can be used to restore.

For Differential backup, it is always directly related to its originating Full Backup. It will back up all data added and changed since the Full backup was done. Therefore, compared to a full backup, the backup time and image file storage space required are both less. If one of the differential backup image files becomes damaged or lost, it will not affect others. But, if the full backup is damaged or lost, all related differential backup will be invalid. All data can be returned to the state when the Differential Backup was done.

jeffb99

Thanks for this.  Just to be sure I understand, Differential backups always refer to the Full, not previous Differentials??  So its OK keep only the Full and the most current Differential backup, and earlier Differential backups can be deleted?  This would appear to require less storage space since only 2 files (the Full and most current Differential) are required, not ALL image files as is the case with Incremental backups.  Is this correct?

admin

@Jeffb99, You are right.