RBAC vs. DAC and Incremental vs. Differential

Crunchyhippo

I'm having a dickens of a time differentiating the difference between RBAC/DAC and Incremental/Differential. Maybe it's using different sources, but different study guides all seem to say something different. Can anyone shed any light on these? Thanks tons.

illmatic3285

Incremental- the archive bit for a file is turned off so unless the file is changed by the next backup the file will not get backed up again.

Differential- the archive bit for a file is left on so whether or not the file is changed by the next backup it doesn't matter as the file will get backed up again either way.

What this means for an incremental system is that come restore time after the last full backup you will need every incremental tape since that last full backup. As for differential you will only need the last full backup and the last differential tape created. So in the end incremental produces faster backup times but slower restore times and differential has slower backup times but faster restore times in general.


.....uuuhhh stay tuned for access control methods the game is back on GO BIG BLUE!

sprkymrk

Here is some good information on the backups when someone else asked a similar question recently:

http://www.techexams.net/forums/viewtopic.php?t=27881

sprkymrk wrote:

A little clarification, although I assume this is what you meant, with incremental, you need all the previous incremental backups and the last full backup to do a restore. With differential, you need the last differential and the last full backup to restore.

Differential - faster restore but slower backup. This backup does not clear the archive bit, which causes it to be backed up again the next time a differential/full backup is run. This is why a differential will continue to back up files that have already been backed up (since the last full backup).

A full backup will clear the bit, however a full backup does not care whether the bit was set or not, it backs up everything you told it to back up whether the bit is set or not.

Incremental - slower restore but faster backup. This type of backup clears the archive bit, so unless the file is modified by some other program/user, it will not get backed up again. However, this is also why you will need every incremental backup made since the last full backup in order to do a full restore.


Hopefully I didn't make any glaring errors in my above summary...

And have you checked out the Security+ TechNotes? Johan explains access control pretty well here:

http://www.techexams.net/technotes/securityplus/mac_dac_rbac.shtml

If you still need help feel free to follow up with any more questions.