Incremental backup (newbie question)

My backup plan follows:
1) I have 2 external USB drives, which I plan to rotate.
2) In between Full Backups, I plan to do daily Incremental Backups.

My question:

Are Incremental Backups "incremental" with respect to the particular Full Backup to which the incremental updated is added?

Or, are the Incremental Backups "incremental" with respect to the archive bit on the drive backed up.

Put differently, each time I switch USB drives, do I need to do a new Full Backup before I append an Incremental? Or, can I switch USB drives and continue Incremental Backups, and the software will recognize that I am doing an incremental backup to a particular full backup?

Hope this makes sense. Thanks,
-steve

 

I would assume that TruImage looks at the specific full backup online, then at any online incremental backups, and then creates an additional incremental backup in order to match the current state of the partition being backed up.

That's my assumption, anyway. This would be easy to test; just make sure you first create a separate backup process somewhere else so you can recover in case this doesn't work.

But I think it should.

 

The Archive bit is not used -- I don't think any sensible program uses the Archive bit these days. Backup programs used it back in DOS days but too many other programs used it for other purposes and it became an unreliable indicator.

If sectors have been written to since the last backup, then those are the ones in the inc. It appears that one can, with appropriate software do a direct edit of a sector and this will not be detected by ATI, presumably, with normal file activity, the MFT is updated and perhaps that is where ATI looks for changed (written-to) sectors.

 

I dont bother with incremental backups as a full backup is actually quicker! I tired it once and it took 2.5 hours where as a full backup is only 40 minutes.

Acronis takes for ever to look at the last full backup compare this and then start backing up files.

So if you have the space then a full backup is the way to go. Also if you need to restore, a full backup will be quicker than restoring a full base backup and then one or more incremental backups.

 

Must be something wrong somewhere.

A full for me takes approx. 2 hours; an inc 12 minutes.

 

An incremental backup must have access to the full backup to which it is intended to add an increment, as well as all prior incremental backups to this full backup. It must also have this access during a restore. The best policy is to keep the full set together in a folder on a single drive. If it does not have this access during creation of an incremental, it will simply create a full backup. If it does not have access to the full set during restore, it will not restore.

Good luck.

 

If you can it's better to do differential backup. With incremental you'll do say Monday full backup, then tueday to sunday incremental. If you do a restore then you need all incrementals from tuesday to sunday. If you do differential then you only need the day you want to restore, say thrusday plus the monday full backup, it doesn't matter if you lose the other days.