On heavily loaded web servers with many users making many requests, the access.log file will continue to grow in size until it is removed. However, simply removing the file while Apache is running will not fix the issue. Apache will need to be restarted and this process should be set up to run on a periodic basis.
As Apache states in its Log Rotation documentation, the access log file typically grows 1 MB or more per 10,000 requests. The simplest method to manage this process is to set up a script to run regularly (e.g. weekly or monthly) during off-hours. The script should contain the following lines on a Windows monitoring station:
net stop "up.time web server"
del "C:\program files\uptime software\uptime\apache\logs\access.log" net start "up.time web server"
The script should only run for a few seconds and the web interface will only be down for those few seconds before coming back online. No data will be lost because the data collector is not touched and only the web interface is temporarily interrupted.