On VMTN someone hit a situation where the sps-runtime.log.stderr log file grew extremely large on their vCenter Server Appliance (7.0 in this case). I have seen this before, and sizes over 10GB are not uncommon. The sps-runtime.log.stderr file belongs to the service that provides the Policy-Based Storage capabilities. You can of course stop the service and then delete the files, and restart the service again. However, you could also empty the file by simply doing the following on the command-line:
cat /dev/null > /storage/log/vmware/vmware-sps/sps-runtime.log.stderr
This results in a 0kb file immediately.