automatic hard linking

[t.littlefield at comcast.net]

Hello,

A co-worker and I were talking about various ways to do 'backups' to try and
prevent data loss.  The topic came around to a file system we had used
at a previous job.  I can't remember the specifics, but we believe it was
a Network Appliance system.

One of the cool features it offered was a series of hourly, nightly and
a monthly backup of files.  We kind of surmised that it was some sort of
hard linking of the same file name in a different directory...  i.e.

~/foo.txt

hourly.0/~/foo.txt

So, if you accidentally deleted your home directory copy, you could still recover
it for a short time.  Once it made it past X hours, the file would start getting
removed from the hourly.n directories.  We were never admins on the box
nor do we have experience with it, so the hard link is just a theory...

A quick google search on automatic hard linking didn't turn anything up.  Is
there a package anyone knows of that registers for file system events and
will create temporary hard links in another location for 'accident prevention'.

This isn't a backup strategy (obviously) just a method for easily recovering
files when that "Oops" happens...

Thanks for the help.

- Todd