I've seen the occasional blip here, but this is the first time I've seen a complete outage of this instance. Hoping @Salamander wanders through and gives us the scoop?
I often check the available disk space and expand it when it reaches ~90% occupancy. I increased it by 20 GB last Sunday night before traveling for work and did not expect it to fill up so quickly, but I underestimated the current rate at which the disk is being filled. This morning the disk was filled but I did not notice until after work.
I will keep a larger empty buffer to avoid this happening, but I also want to find some way to save disk space. The overwhelming majority of the space is occupied by images that are duplicated from other instances.