Diskspace decreases when updating thumbnails in iPhoto?

Question

I recently had a problem with iPhoto showing the same thumbnails on multiple images. I cleared the issue by updating the thumbnails. But by doing that my internal drives free space dramatically decreased, down to below 1 GB of free space! And I had to stop updating thumbnails.
I have my iphoto library on an external drive, and assumed that all databses and thumbnails was stored inside that package, isn't that right? and if so, why is space decreasing on the internal drive instead of the external? Should it decrease at all?
My son has a very tiny iPhoto library on the internal drive (approx. 300MB) could that somehow have tricked iPhoto in to believing that my library is also internally stored?
I hope someone can help me answer my questions, so I can get my space back:)
Thanks in advance!
Kind regards,
Thomas Detlefsen

Answer 1

down to below 1 GB of free space!
You have a big problem and you need to fix it fast. Very fast.
OS X needs about 10 gigs of hard drive space for normal OS operations - things like virtual memory, temporary files and so on.
Without this space your Mac will slow down as the OS hunts for space on the disk, files will be fragmented, also slowing things down, apps will crash and the risk of data corruption - that is damage to your files, photos, music - increases exponentially.
Your first priority is to make more space on that HD. Nothing else can be done until you do.
It's most likely that the space on your internal is eaten by temporary files. But it doesn't matter a whit. Your are in grave danger of serious dataloss.