Our school has been running Moodle 2.2 for over a year with Moodledata on a 72 GB disk volume with less than 50% utilization. We are running on Ubuntu with Apache and Postgresql. We use a separate volume for Moodledata and the database storage. Over the summer, we upgraded to Moodle 2.7. After the upgrade, the disk usage jumped to 60% and a few days later the drive went to 100% utilization. I reconfigured the drives on the server so that the volume was 144 GB of disk space and of course, disk space utilization dropped to 50%. Disk space utilization has been steadily growing and now it is up to 80%.
The backups are directed to a separate volume, so that they shouldn't be the issue. The Moodle system has had almost no usage since it is summer here, so I am very concerned that as school starts, we will run out disk space again. Since the system ran all last year using less than 50% of a 72 GB volume, I don't understand why just upgrading to version 2.7 has made the system approach filling a 144 GB volume.