Where has all my storage space gone? This is actually starting to annoy me!

Every so often, I get the 'Storage space running out' notification. I go into my settings, and it says I have 60MB left.

The thing is, almost a month ago I erased the device because of the same thing - I have my 1.8GB available, and everything was fine and dandy, until now.

I haven't installed anything recently, however I suddenly only have 60MB left. I added up all the app sizes according to Android:

Chrome - 65.55MB
Can You Escape - 34.75MB
Facebook - 31.77MB (why does Facebook use so much?)
Gmail - 27.46MB
Skype - 24.04MB
Facebook Messenger - 19.74MB
Search - 18.98MB
Tapatalk - 17.50MB
Hangouts - 17.33MB
Maps - 13.49MB
Google Play Services - 13.49MB
Google Play Store - 10.91MB
Youtube - 10.80MB
System - 10.27MB
Google+ - 9.39MB
Shazam - 8.37MB
Titanium Backup - 8.30MB
Spotify - 6.93MB
Ingress - 6.70MB (I still have 3 invites if anyone is interested)
Media Storage - 4.50MB
3G Watchdog Pro - 4.05MB
Cerberus - 3.02MB
Secret Codes Revealer - 2.99MB
Email - 2.93MB
Contacts Storage - 2.62 MB
Super SU - 2.50MB
Screen Standby - 2.27MB
Settings - 2.20MB
Titanium Backup Key - 2.12MB
DeskSMS - 2.09MB
Exchange Services - 2.05MB
Browser - 2.05MB
Root Explorer - 2.03MB
TalkBack - 2.02MB
Beats Audio - 1.90MB
Google Services Framework- 1.86MB
Google Text-to-speech - 1.78MB
Gallery - 1.75MB
Spirit UL - 1.66MB
Contacts - 1.65MB
Spotify Community - 1.53MB
Sound Search for Google Play - 1.34MB
I then have ~80 apps &lt; 1MB in size.


Add them all together, and I get 490.53MB - nowhere near the 1.9GB Android says I am using.

Why is Android reporting me using 1.9GB? What is using this memory? Why isn't it showing in the settings?

And above all, how can I fix it?

I am using a Samsung Galaxy SII with Android 4.2.2 Cyanogenmod 10.1

Output of df shell command:

Filesystem               Size     Used     Free   Blksize
/dev                   395.3M    48K   395.3M   4096
/storage               395.3M     0K   395.3M   4096
/mnt/secure            395.3M     0K   395.3M   4096
/mnt/asec              395.3M     0K   395.3M   4096
/mnt/obb               395.3M     0K   395.3M   4096
/mnt/fuse              395.3M     0K   395.3M   4096
/system                503.9M   340M   164M   4096
/cache                  98.4M    72M    26.4M   4096
/efs                    19.7M     8.3M    11.4M   4096
/data                    2G     1.9G    83.9M   4096
/preload               503.9M   204.3M   299.7M   4096
/mnt/asec/com.keramidas.TitaniumBackupPro-1     2M   100K     1.9M   4096
/storage/sdcard1         7.4G   126M     7.3G   4096
/storage/sdcard0        11.5G     4.6G     6.9G   4096
/mnt/secure/asec        11.5G     4.6G     6.9G   4096
/mnt/asec/com.thales.android.view-1     3M     1.1M     1.9M   4096
/mnt/asec/com.nianticproject.ingress-1    26M    24.4M     1.5M   4096
/mnt/asec/uk.co.nickfines.RealCalcPlus-1     2M   340K     1.7M   4096
/mnt/asec/com.mikersmicros.fm_unlock-2     3M  1004K     2M   4096
/mnt/asec/com.eclipsim.gpstoolbox.pro-1     2M    76K     1.9M   4096
/mnt/asec/com.eclipsim.gpsstatus2-1     2M   912K     1.1M   4096
/mnt/asec/com.farproc.wifi.analyzer-1     2M  1000K     1M   4096
/mnt/asec/com.shazam.encore.android-1    10M     7.8M     2.2M   4096
/mnt/asec/com.hutchison3g.planet3-2     5M     3.8M     1.2M   4096
/mnt/asec/com.google.android.apps.plus-1    20M    18.5M     1.5M   4096
/mnt/asec/eu.chainfire.supersu.pro-1     2M    64K     1.9M   4096
/mnt/asec/com.speedsoftware.rootexplorer-1     3M     1.4M     1.6M   4096
I use DiskUsage for situations like this. It graphs the directory structure for you in a very pedagogical way to show you what directories (and subdirectories) that are taking up the most space. It literally solves situations like this in 15 seconds for me, because I'll see a big square with the text "Movies" or something on it, realizing I completely forgot I put an entire season of Wonders of the Universe on my device or something — or I'll se a folder with a name of an app that has long since been deleted with a bunch of useless cache :)

Try it out, I'm not sure how well it works on non-rooted devices but I think it should work on those as well, I don't think it does anything else than list directories and add their content size up.