On a Samsung note 10.1 with 32G when I go to settings I can see 25GB available storage. Besides that, when I am trying to copy files from my ubuntu box to the tablet (connected through the USB) I am getting an insufficient storage message. Checking the properties of the mounted volume I only see 200MB free on it.
How can I fix it?
mtp-tools
package installed on your Ubuntu PC? My answer here might prove helpful (ignore the Kindle, focus on the Ubuntu part ;)