Automatic documents backup

Question

I am looking for a backup solution to handle large documents well. I don't think that "back-up" software is what I am looking, but it is the best term I can see. We are not interested in recoverability or restoring the system as it is.

My wife is a photographer that takes about ~3GB/week worth of pictures. She would like to have to store all the pictures in an external storage. Yet, she would rather work on the pictures locally, when she uploads the pictures from camera or edits them.

We are looking for a tool that that treats the local drive like a cache rather than desired state to be restorable. So here are the requirements that we desire:

1. You can work on your local data offline. We cannot just operate on the external storage directly.
2. Any addition/modification changes to the local data will be propagated to the external storage the next time it is connected. Hopefully automatically.
3. Any deletion on the local drive shouldn't be propagated to the external storage.
4. Deletions on the storage drive would propagate to the local one, or at least once it is deleted it is never imported again from the local drive
5. Not interested in state restoration. We don't care about how the storage was like two weeks ago. We'll never want to restore that stage.

Desires, but not requirements:

1. Track file content rather than file names/paths. We would like to be able to change the directory hierarchy of the external storage without confusing the tool.
2. Restoration of a file state. While we aren't interested in the state of the entire backup, it will be nice to see the changes each document went through.

In my simple view, this is what a document backup should look like; as opposed to system backup where I am always interested in restoring the system if it fails. Are there any software that uses this model? Any suggestions for my backup flow?

Answer 1

I really think the Time Machine will do just what you want here. Am I overlooking something?

Also, have you looked at Apple's Aperture? It has pretty comprehensive workflows for photographers, including image archival and versioning.

Answer 2

A version control system (VCS) like git would meet most (all?) of your requirements, at the cost of being more technical and likely requiring command-line use for some operations. That said there are good GUIs for most popular VCS on all major operating systems.

Addressing your points:

1. You can 'check out' the latest version of all files to work on, then 'push' the changes back to the main storage.
2. Automatically pushing changes back would be quite easy to set up with some scripting.
3. You choose which changes to keep. Any mistake can be reverted.
4. You can remove files from the current state of the files easily, and undo this if it was in error.
5. It is possible to remove history from version control, but this would be a weak point in this solution (and probably the most technical part).
6. git tracks files by content. You perform moves and renames with its tools without losing history of the files.
7. Version control allows any version of any file to be easily accessed.

Some programs to check out: git home page and on StackOverflow, mercurial/hg. A lot of resources are available on the web on the subject although much of it will be aimed at programmers.

PS - I know this is a crazy solution :)