Internal Memory Full, My Motorola G 4G (XT1072) is full (4.6 Go) whereas the used storage is only 1.4 Go. I get messages of 'low internal storage' with and without the SD card.

I tried several 'storage analysis' apps, but got no insights from it.

This post suggests that the phone must be rooted to find the files taking all the room : Phone memory full and it shouldn&#39;t be

Edit 1 : Wiping cache partition did not solve the problem

Edit 2 : A music App (Deezer) and all the music data is responsible for this. I moved it to the SD card, Android says it is stored on the SD card, but Disk Usage App showed clearly that the music data is stored in the internal memory. 

Is rooting really necessary ? Any other solution ?

Edit 3 : Deezer messed up. Despite Android's settings for this app, you have to fix a settings. In the actual Deezer app, in settings, there is an option to change storage settings. It says that you will lose all data, and you do. However, once you've requested this, and it has deleted all the music clogging up your phone, it then automatically downloads everything again to your SD card. Bit time-consuming and definitely better over Wi-Fi, but the end result is life as you were, and lots more space on your phone!
Well rooting is not bad actually it can help a lot with many apps and it helped a lot with my internal storage problem, if you decide to root your phone download "link2sd" then make 2 partitions on your SD card one of them is fat and leave the other one unformatted, mount the SD card and then open link2sd it will ask you to choose the format for the second portion choose ext2 choose one of your apps and choose crest link and now the ext2 part is added to your internal memory