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Must do full backup after modifying the selection list - Part 1

Created: 10 Sep 2011 • Updated: 13 Oct 2011
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Symantec single video player.

I have captured a series of  silent videos to put to rest any lingering doubts as to whether this rule is true.  The videos are on the fast side, but you should pay attention to the end when the contents of folder a2 are displayed.

Q: Suppose I am doing a full backup during the weekend and daily incremental backup during week-days and I need to add a directory, Directory-A, to the selection list on Wednesday morning, does the Wednesday incremental backup backs up all the files in Directory-A?

A: NO. An incremental backup only backs up the modified files in any directory, including Directory-A.  YOU MUST DO A FULL BACKUP AFTER YOU MODIFY THE SELECTION.  This is to establish a new baseline.  This is regardless of whether you are using the archive bit method or the modified time method.  This rule also applies when you are doing full backups + differential backups.
 
The only exception to this rule is when you are doing True Image backups, but you would need to purchase the ADBO option.
 
I have captured a series of  silent videos to put to rest any lingering doubts as to whether this rule is true.  The videos are on the fast side, but you should pay attention to the end when the contents of folder a2 are displayed.
 

Test Scenario

The test scenario uses 2 directories with 4 files each. The sequence of events are as follows:-
  1. file a1 in each directory is modified
  2. a full backup is done on directory a1 and the results examined
  3. file a2 in each directory is modified
  4. an incremental backup is done on directory a1 and the results examined
  5. file a3 in each directory is modified
  6. directory a2 is added to the selection list
  7. an incremental backup is done on directories, a1 and a2, and the results examined
This test is done using the archive bit method, the modified time method and True Image backup.
 

Result

The results for the files in directory a2 which is added to the selection list AFTER the full backup and the first increment backup are as follows:-
 
 
File When modified Backed up by the second incremental backup?
Archive bit method Modified time method True Image backup
a1 Before full backup Yes No Yes
a2 Before first incremental backup Yes No Yes
a3 Before second increment backup Yes Yes Yes
a4 Not modified No No Yes
 
Note that file a4 is not backed up when either the archive bit or the modified time methods are used.  These are the common methods used unless you have purchase ADBO which gives you True Image backups.
 

Conclusion:

You have to do a full backup to backup all the files in any additional directories that you add to the selection list.  Otherwise, you would not have all the files in the additional directories.
 
*Note: Since I can only include 1 video per video content,  this video only shows the Archive bit method. Please make sure to watch  the other 2 videos in this 3 part series here: