Backups to external disk

[Jamie Wilkinson <jaq spacepants org>]

Hi!

I've got many gigamabytes of photos, a big external drive, and a laptop.
The laptop is where I run f-spot, but the disk is relatively small, so I
can't store all the photos on it.

I was on holiday this last fortnight, taking more photos, and thinking about
this: I do still want to be able to browse my photos on the laptop even
without the disk attached.

An idea came to me:

  Store relatively low resolution copies on the laptop, and keep the masters
on the external disk.

Even at resolutions of 1024 wide, this is only a meg per photo (though of
course I'd like it to be configurable, I'd probably only keep them 800
pixels wide for browsing) which is about 10 times smaller than my 20D makes
them.

Of course, the external disk isn't always available, so I guess I need a
"Synchronise" or "backup" button somewhere.  Also sufficient warning when
trying to edit photos offline, saying you'd need to plug in the backup disk.

What do people think about this?