Since I upgraded to iOS 9 beta 2, the iCloud backup stopped working for a few days. Then, I tried to backup manually and it prompts me that my iCloud account has insufficient space. That was unusual because I always got 1 GB left (out of the 5 GB free storage) after doing an iCloud backup on iOS 8. Later when I purchase an extra 20 GB, I found that the iOS 9 backup takes up 7 GB! (previously less than 2 GB for the same device on iOS 8). There was no new apps installed nor there were any large files added in these days. Wonder if anyone here have the same problem?