Q: iPhone 6 plus storage usage spikes over 30GB

Hey vinedine,

I would suggest reviewing your storage usage in iTunes to get another perspective of the data that is being stored on your iPhone.    See the "View storage usage for your iOS device in iTunes" in the article below.  

Take a look at your Mail and Messages apps.  Many times, the photo and video attachments in those applications can take a lot of space on your device.

See how much storage you've used on your iPhone, iPad, and iPod touch - Apple Support
https://support.apple.com/en-us/HT201656

If your device is near its capacity or you get an alert that your storage is full, you can remove some of your less used content to make room for more.

 

iTunes displays how much space the selected songs, videos, audiobooks, and apps use in the status bar on the bottom of the screen. You can also see this information by selecting an item and then choosing File > Get Info. The size is available in the Summary tab.

 

You can transfer or sync content to your computer from your device. If you want to remove certain types of content from your device, learn how to manually manage content using iTunes.

Hope that helps ...

- Judy