If you don't need logging it can be disable see below, if you need it you should setup log forwarding so it's not tying up space on your 7100. If you need to keep the logs make sure you do show smdr first with output redirected to a text file before clearing the log.
To View the log use from enable prompt:
To clear the log use the followingfrom enable prompt:
clear voice logging smdr
To disable the loging use the following from configure prompt:
no voice logging smdr