"But wait... there is more."
There exists yet another way for detecting file changes and that's to rely on someone else to track changes for us.
Nearly all modern file systems employ a form
to keep a log of all major changes to the folders and files.
These records are kept to allow for automatic self-consistency checks and repair after computer crashes, sudden power-offs and other unfortunate events.
is of this kind.
The journaling can also be configured to record changes to the file contents
This doesn't record what
has been written, but it does record where
the change was and when
And this happens to be exactly what we need for delta copying purposes.
The main drawback is that this makes delta copying dependent on an external component.
Another trade-off is that tracking writes causes the journal to be updated much more frequently, grow in size faster and have a shorter time coverage
This has system-wide consequences, and it also increases chances of not having complete
change log for a file that was last copied long time ago.
Excessive journal use with write tracking is also likely the reason why on Windows the tracking is off by default.
Last, but not least is that this is a technically complex feature and it's just plain hard to implement correctly with all i's dotted and t's crossed.
Nonetheless, when deployed with due thought and care, journal-based delta copying can be exceptionally effective
The prototype is in the works and the initial revision should be making its way into Bvckup 2 builds shortly.