Archive Bit

The backup strategy that I used for years with BackupMyPC (BUMP) was to do a full system backup on the first of each month to tape (Travan5). I had three sets of full backup, each a month apart. Then nightly at about 1:00 am I automatically fired off an incremental backup.

The strategy by which the BUMP incremental backup was able to determine what to back up incrementally was the archive bit, which was reset on every file when the full system backup was done thus any file with the archive bit set was a candidate for the incremental backup.

I have just completed a full system backup to my 1/2T JBOD drive. Took about the expected 27 hours. (277 Gb). However, on inspecting the files that were copied, I find the archive bit is still set in the majority of them. As I have the automatic Incremental backup scheduled to fire at 1:00 am tomorrow, I am worried taht the “incremental” backup will actually re-backup many of the files that have not changed since the Full System backup ended at around noon today.

What do I need to do to be able to achieve the backup strategy with which I am familiar?

Hello, Comodo – this feature is an important one. Backup programs have been turning off the Archive bit on the original copy for decades. That’s what that bit is for: if A is on, the file needs backing up.


Many backup programs use different techniques for incremental backups.
With Comodo Backup 3.0 (which is now BETA) you can perform incrementals at block level (64KB).
So if in a 2GB file only 1 byte is changed, the incremental will not contain the entire 2GB file, but a single 64KB block.
I’m afraid the “archive bit” technique can’t be used with Comodo BackUp