All services have been stable since 01:15 UTC. The backup is now permanently throttled so it no longer slows down normal operation.

From about 01:00 to 01:15 UTC the status pages on statuscx.eu and parts of the reseller API responded very slowly or not at all. The nightly backup saturated the host's disk. We stopped the backup and restarted it throttled; all services have responded normally since. We are monitoring until the backup has finished.