Bash – modification time rsync option

None of the tools you are considering provide guarantees against concurrent modification. However, do you really need a point in time snapshot. If so use the LVM snapshot option given above. As you have given rsync as an option I assume that disk to disk backup is an option.

Least secure is dump which takes a copy of the disk blocks as they are read. Given the size of your data there is likely to be significant differences between the directory information and the data. For disk to disk backup you could consider dd to partitions of the same size as an alternative. Both solutions do essentially the same thing and have the same problems.

Tar will read the files one by one and will read to the end of each. If a file is renamed or deleted while tar is backing it up tar will back up the file it started reading. It is a reasonable solution for log files.

Rsync behaves like tar, but only copies changes. Essentially it will copy all changes to the directories. With a date based log rotation scheme (logfile.yyymmdd) instead of the common rotated version scheme (logfile.1 logfile.2gz ...). It can efficiently backup your logfiles.

I'm a little bit confused about what you're trying to do. Rsync, all by itself, will only transfer new/modified files. So if you transport data on a hard drive once/week, you can run rsync periodically and it will no more bandwidth than (and possibly less than) the solution you're proposing using find.

All this work with find seems like you're just duplicating features that are already there.

If you really want to use find, you don't need xargs or xargs-like features; just do this:

find ... -print | rsync ... --files-from=-

Where ... is "whatever other options you feel are appropriate". This causes rsync to read a list of files from stdin.