I had similar problem as OP after making backup of my ROM (using CWM Recovery) before flashing 4.3 (CyanogenMod 10.2)
I found out that file system in 4.3 is different (due to multi-user build) so:
I had storage folders (for my files etc) - 0, obb, legacy
- 0 being my data in 4.3, but about 3 GB of space was missing on my phone.
After research I found that my /data/media folder had files from previous ROM inside.
Let me make wider explanation, I ran Android Terminal Emulator
, used "su"
command to get SuperUser full access, and cd'd to /data/media folder.
And instead of having this kind of "ls"
I had something like this:
The solution which was the best for me was to format /data/media folder using CWM Recovery. Of course I lost all of my files, but the space was back
PS sorry for my bad English