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Can anyone recommend a method to export a subset of a file system and to synchronize changes to those files with the original file system?

Suppose you have:

  • a laptop with a small-capacity SSD (e.g., 128 GB) and
  • a NAS device containing all of your data (e.g., 1.2 TB) in a unified file system.

How do you go about working on your files while away from your NAS and sending modifications back to the NAS later on? The most direct solution appears to be an application that:

  1. Indexes the file system on the NAS.
  2. Allows you to "check out" some of those files/directories (i.e., make local copies) on your laptop when the NAS is connected.
  3. Identifies and synchronizes changes to those files on a regular basis (e.g., the way Dropbox automatically syncs files) whenever the NAS is available.

Is anyone aware of a solution that does this? Or does someone have another approach to managing files when working on laptops with small hard drives?

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Briefcase files work well... At least, they did in Windows 98.

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+1 for the memories – Phoshi Jul 10 '11 at 15:21

You can use Dropbox together with symbolic links in order to synchronise folders outside of the Dropbox. Mac OS X, Linux and Windows all support symbolic links through a terminal at the least.

On popular Linux WMs/DEs symlinks can be made by dragging a folder and holding the correct key combination (ctrl+shift if I remember correctly). On Windows the easy option is a tool such as Link Shell Extension. AppleScripts are available for OS X.

As for your NAS question, you may do well to look into a version control system such as Git or Mercurial.

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You could look at SpiderOak. It's like a more configurable version of Dropbox, that (amongst other things) allows you to choose which directories to synchronise rather than being limited to a single one.

It does however use its own Internet-based cloud storage, so it might not be so useful if you particularly want to use a local NAS.

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Distributed source control systems won't be of any good, since they require a full copy of the whole repository with the history to be able to work offline. Centralized server software like Subversion allows you to check out sparse directories, meaning that you specify which folders you want to work on and the rest is not downloaded. On the other hand, Subversion keeps a local copy of each file, so if your limit is the hard disk, it may not be good anyway.

If you don't mind going the commandline route, you might want to check the programs/algorithms behind the wonderful rsync, like rdiff. Here's an article which uses it to emulate offline rsync functionality. You could adapt those scripts to work only on files existing in your sparse checkout, which should be fine as long as you don't need to store delete actions.

Don't know much about it, but maybe Unison provides similar functionality, according to their manual they allow syncing only parts of the tree.

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