Incremental backup behaviour?

Hi all,

New to the software, I’ve decided on Duplicati 2.x after an exhaustive search on backup tools. I’ve got the following (dumb newbie) question, regarding incremental backup behavior with an external drive.Hope I’m posting in the right spot:

I plan on regularly backing up my C drive user files to my laptop’s external hard drive (and either OneDrive and/or GDrive, but that’s not relevant to this post). My practice has always been to unplug the drive periodically for convenience, when I move the machine off my desk - other rooms in the house, out of the house etc.

How does incremental backup handle the removal and subsequent re-connection of an external drive, assuming it’s removed and reconnected between scheduled incremental backup times?

Simple use case example: Say I have backups set for twice a week, Saturdays 9:00 AM, Wednesdays 11:00 PM. AM. So check my logic - if I removed the drive after the Saturday backup completed and before the Wednesday backup began, this should cause no issues.

Correct? Thanks in advance!

Correct. Even if the drive is removed during a backup Duplicati will be able to recover when the next backup starts (though to be fair if the drive is disconnected during a backup you’ll probably get an error message about the destination no longer being available).

One thing you should know for USB drive backup such as you describe is that when if you have a Sat. 9A & Wed. 11A backup schedule a backup will only start if the drive is connected at the time of the backup (Sat. 9A or Wed. 11A).

I THINK if the computer is turned off / asleep during the normal backup time then if the USB drive is connected when the computer first turns back on (after “missing” the scheduled start time) then the backup will run as expected.

But if the computer is on without the USB at Sat. 9 AM, then the USB drive is attached at 9:15 AM the backup will not automatically start.

In other words, destinations are checked for availability at the time of the backup start only. We would like to be able to add “drive mount” detection in the future, but at present do not have a plan of when that might happen.

Awesome, thanks for the quick response! Regarding a sleeping computer. I had already planned to adjust Power Management settings as appropriate to avoid the issue.