I have a Galaxy S2 running Android 4.1.2. It has a 12GB internal HD, and a 16GB SD card.
I keep getting errors from various programs telling me I am running out of space. BeyondPod won't download new episodes, Evernote keeps putting up a notification of a lack of space (even though it seems to be storing everything), and sometimes apps won't update.
I have tried to ensure I have no superfluous apps, and I haven't really changed the apps I use since I first ever started using the device. I keep any large files, like music collections or videos, on my SD card.
When I connect my device by USB to my Linux computer and check the properties of my 12GB HD, it says 9.9 GB is used. But if I browse the files, every folder seems to have barely kilobytes of information.
Why is my 12GB HD filling up, and how do I clear it out so I don't get these errors?
Update: My phone is rooted, so if that is something that can help me in this situaton, then root access is available to me.
insufficient-memory
tag to your question. Please follow-up to its tag-wiki, where you find some "first-aid", e.g. links like What can I do to manage my phone's internal storage? Note: that tag focuses on internal storage.