Community Server contains an EventLogJob task that removes Eventlog records older than two days. I use the Eventlog a lot to track custom tasks and various other processes, so I want to retain more than two days' worth of records in my event log.
The CommunityServer.config file <tasks /> area contains the EventLog task configuration. We could disable the job, but since cleaning out the eventlog periodically is a good idea, we'll add a "days" attribute. If you look at the EventLogJob task source below, a "days" attribute is supported but not present in the cs.config by default.
So we add it as shown below in bold.
<task name = "EventLog" type = "CommunityServer.Components.EventLogJob,
CommunityServer.Components" enabled = "true" enableShutDown = "false" days = "10" />