Disk Usage – How to Understand What’s Taking Up Disk Space

You can use a wiki like Zim - a Desktop Wiki and save its files to a Dropbox folder. For Android you can use WikiMind note to work with the Zim Wiki. I'm sure there are other apps that can work with Zim's files since they're just text with wiki markup.

EDIT #1

Other options for Android if the $3 price for WikiMind is too steep.

• WikiMind Lite
• ZimDroid (it's under development and not usable but something to keep an eye one)
• List of "Wiki" apps on appbrains
• Epistle a Markdown editor

Repeated execution of

sudo du -x   -d1 -h /

(down the directory tree) should tell you where the space is consumed. That probably explains without further investigation which application is causing that.

invisible files

If du doesn't show these files then one of the possibilities are deleted files. A file (or rather: its name i.e. its entry in a directory) can be deleted while the file is still in use. As long as there is a valid file descriptor pointing at this file it covers space on the volume (if it is not an empty file...).

cat >file &
ls -l file
rm file
ls -l file
# PID of cat is 19834
ls -l /proc/19834/fd
lrwx------ 1 hl hauke 64 11. Feb 19:16 0 -> /dev/pts/0
l-wx------ 1 hl hauke 64 11. Feb 19:16 1 -> /crypto/home/hl/tmp/file (deleted)
lrwx------ 1 hl hauke 64 11. Feb 19:15 2 -> /dev/pts/0

You can find these files with find:

find /proc/ -mindepth 3 -maxdepth 3 \
-regex '/proc/[1-9][0-9]*/fd/[1-9][0-9]*' -type l -lname '*(deleted)' \
-printf '%p\n     %l\n' 2>/dev/null

It may be one single huge file or a bunch of smaller files which cause your problem. There are about 30 such files on my system now (belonging to only five processes). ls -l shows the size of these files but it seems not to be possible to get this value from find.

After killing the process the space becomes available to the file system (df) again.