Squid writes to a number of log files unless you disable them in squid.conf. You must periodically rotate the log files to prevent them from consuming too much disk space. Squid places a lot of importance on log files and exits with an error message when it can't write to them. To keep disk space consumption under control, use the following command in a cron job:
% squid -k rotate
For example, this crontab entry rotates the logs every 24 hours, at 4 A.M.:
0 4 * * * /usr/local/squid/sbin/squid -k rotate
This command does two things. First, it closes the currently open log files. Then, it renames the cache.log, store.log, and access.log files by appending a numeric extension. For example, cache.log becomes cache.log.0, cache.log.0 becomes cache.log.1, and so on, up to the value of the logfile_rotate option.
Squid keeps only the last logfile_rotate versions of each log file. The older versions are simply removed during the renaming process. If you want to keep more copies, you need to increase the logfile_rotate limit or write some custom scripts that move the log files to a different location.
See Section 13.7 for additional information about rotating log files.