Clearing logs files is an important step that you need to carry out frequently on your Server. As logs pile up, Server struggles to update it. For instance, updating a 10-byte file is not like updating a 10-megabyte file. It takes I/O and latency, which affects the overall performance, especially if you are running on a fine level log. Here is how to clean the logs: from the ArcGIS for Server Manager window, activate the Logs tab and click on Delete Logs to clear all the logs from all GIS servers. You can also use the settings to set an expiry for the logs. However, it is recommended that you use severe mode in a production environment unless you are monitoring the system.