Why does `df` indicate no available space when used is much less than total size, on my VPS? [duplicate]

Yes, contact your provider and tell him he has overcommitted his storage and he needs to fix it ASAP.

Explanation: With some type of VPS servers, you don't have a disk image with a fixed and guaranteed size. Instead, your file system is really just a subdirectory of a larger file system with a certain quota which is reported in your VPS as the disk size.

Problem is that if the provider overcommits storage and the real disk gets full, you end up with the problem you are facing now: The disk is reported as full even if you only used 50% of what the VPS reports as its size.