Is there something like hardlinks that split into separate files on modifications?

Question

Let's say files orig and copy are huge but identical files. In order to save storage space one could therefore either make copy a soft-link to orig or hard-link both files to the same data. orig must never be modified, while in the future copy may do so.

Can it be achieved that copy becomes a files of its own again the instance modifications are made to it, thus keeping orig unmodified at the expense of loosing the previously saved space again?

Answer 1

Not with Windows as it normally works. You'd need something else to pull that particular stunt off.

If these files are being stored on a server, Windows Storage Server has a Single Instance Store feature that can give you something close to what you want.

OpenDedup is a cross platform file system implementation that does dedupe as well. You could run it on your desktop, if necessary.

There's also non-Windows server options as well. ZFS on Solaris and FreeBSD are particularly popular.

Finally, you can sometimes get lucky with just saving a file, but that depends on a particular application's save implementation.

Answer 2

Some applications allow you to make a file a 'template'.

When you open that file it will create a new instance, with the content and formatting of the template.