Skipping files with dump(1)
Tagged:  •    •    •  

In order to decrease our backup size we decided to skip some files and directories which were not critical. With chflags(1) you can skip entire directories:

chflags -R nodump mydir

But after the next backup iteration we observed the backup size didn't increase at all. A quick glance at the dump(1) manual revealed the following:

-h level --- Honor the user ``nodump'' flag (UF_NODUMP) only for dumps at or
above the given level. The default honor level is 1, so that incremental backups omit such files but full backups retain them.

I was not aware of such exception, thus adding -h 0 to the backup script did the trick.