Incremental backup is not incremental !!


I have setup incremental backup of my server to a remote NAS but each backup is still a full backup and not just difference between previous backup and current ! Did I miss something ? See attached how I have setup it ?



I think (but I can be wrong) that incremental it works without the feature to remove the old backups.

What Virtualmin calls incremental is actually “differential”, I.e. the differences between the last FULL backup and the current data.

hum, it might sound logical as with incremental backup you are supposed to keep previous backups for restore but I see nowhere where you can setup every time it should built a complete backup…

Yeah, Locutus is correct.

So when you’re performing a restore, you would restore the last Full backup, and the last Incremental.

Somehow the wrong name was introduced into Virtualmin some time ago, and now it’s a bit stuck :slight_smile:


yep I understand that so with my backup mode setup as incremental, first backup should be complete (so large files) and then the next backups should contain only changes since first backup, right ? and it’s not what happens !!


It should be as you outlined, yep. If not, it’s possible that either Virtualmin fails to recognize the date when the last backup was taken (I think that date is determined using the timestamp on the backup directory, and compared against the timestamps of all files), or something is making the backup large that is not a file in the user’s home directory (e.g. database - those are always backed up full, since MySQL doesn’t have a way of doing incremental dumps).

It’s not a question of db files as the only big file is just a regular file sitting in web space of a customer account but it’s still included each night in backup unless it didn’t change at all :frowning:
I should fill a bug report I guess ?

Well, we haven’t been able to reproduce any issues like that, and hadn’t received other reports of that problem… what you may want to do, if you haven’t already, is generate another full backup, and see if you continue to have the same problems after that.

It would be a good idea to double-check the system time on all the servers involved as well.


well the system generates each night a full backup, or should I setup it in a different way ?
For system time, I checked and both systems are on time and date correct :wink: something else I could test ?

Our incremental backups are also not working. We only starting using it for the first time recently. I suspect that if you do incremental backups you have to store everything in the same directory?

At present we have this:

Local file /mnt/volume_lon1_01/backups/database/%Y-%m-%d All virtual servers Yes, daily (at midnight) Full

Local file /mnt/volume_lon1_01/backups/incremental/%Y-%m-%d All virtual servers Yes, daily (at midnight) Incremental

Local file /mnt/volume_lon1_01/backups/full/%Y-%m-%d All virtual servers Yes, weekly (on Sunday) Full

So as you can see we use timestamps and different folders for the backups. Could this be the problem? Maybe because the full backup is stored elsewhere the incremental backup can’t detect it and keeps on making a full backup?

The strategy was supposed to be:

Do a full backups once a week on Sundays

Do incremental backups every day of the week, including Sundays. When doing incremental backups, do not backup databases.

Do database backups every day of the week, including Sundays.

I’m also not sure if incremental should run 6, or 7 days of the week. Once I get it working.

Put full and incremental in same folder with different file names instead of different folders. Name incremental something like inc-date and full something like full-date. Should have full backup on Sunday, then 6 incremental, then another full on Sunday gain. The whole DB is backed up on incrementals so no need to separate that.