Rotating backup drives without administrator rights

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Joined: 06 Nov 2020, 22:55

Rotating backup drives without administrator rights

Post by carto »

Hi, I am probably just not understanding how the backup system works. I have one folder on my desktop that I want to back up. I would like back up to three different external disk drives, on a rotating schedule. The folder is quite large so I am thinking I'd like to have one "Full" backup and sequential "Differential" backups on each external drive. Occasionally I might delete some of the old Differential backups, when I am confident I won't need anything on them that I have subsequently changed.

The drives will be connected to the desktop only intermittently, and meanwhile other drives (without the backups) will be connected intermittently. The drive letters change, and as far as I can tell, my limited user privileges (bestowed from above) will not let me reassign drive letters to match up with what I originally told Cobian that I would use for the backup.

I figured I could edit the backup task in Cobian and change the external drive letter to whatever Windows says it is each time. But I am getting results such that I cannot decipher how this all works. I was thinking that it works like this (and I seem to be wrong):

1. I make a "Full" backup on each drive. Not all at once--they are not going to be identical.
2. From then on I am making just Differential backups. One drive is in the office, another at home, and one used for transporting--but they alternate.
3. I plug in one of the drives, edit the backup task so the destination drive letter is correct, and tell Cobian to go for a Differential Backup.
4. Cobian scans the Full backup that's on that drive and compares it with what's in the desktop (source) folder. It makes a collection of files that have changed or been added since the Full backup was made.
5. Cobian writes to the destination drive all of these changed or added files, with the directory structure for each file. Files that have been deleted since the Full backup will not go to the Differential backup, but their subfolders will.

This process doesn't seem to work. For example, it seemed that Cobian was saying that it was writing a Differential backup, but it turned out to be a second Full backup, on the same drive as the first.

Can someone point me in the right direction?

Maybe I am missing a collection of basic info somewhere?

Thank you!
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Re: Rotating backup drives without administrator rights

Post by cobian »

One hint I can tell you to avoid changing the drive letter of those discs is to use the Label parameter. Change the label of your discs in Windows Explorer to something unique, like: MyBackups. Then, on the destination of the task, you could write as a manual destination:


This way the program will check for all connected discs and substitute %DISKLABEL="MyBackups" for the actual drive letter.

To avoid a full backup in this case with rotating destinations, be sure to uncheck: Options-Engine-Advanced- Check destination with attribute method
Luis Cobian
Cobian Backup's creator
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