What takes so much space in my external disk? My external disk (LaCie) is full! When I look at the individual folders within my disk, I see that only little space is occupied by visible documents. So I displayed the hidden files and found small files and directories that all seem to take very little memory. Looks like about 400GB is occupied by some unknown stuff. However there is a directory called .trashes.



When I click on GetInfo, here is what I see



And I can wait for a long time but never get an estimate of the size of this directory. I tried to estimate its size via the Terminal:

$ du .Trashes
du: .Trashes: Permission denied


I tried to delete .Trashes but I get this window popping up



How can I free space on my external disk?

I am on OSX Yosemite, Version 10.10.2.
The default permission on .Trashes do not allow for reading.  Use sudo du -ch .Trashes as this will give you both the total and in "Human-readable" output vs. used sectors which you'd then have to convert.

Also you should not delete .Trashes, just empty your Trash.

If you want to take a graphical look at the contents of the disk use Disk Inventory X, you might find it interesting and can do some cleanup from within the App too.