The exact number of URLs that a FortiGate unit can store in the FortiGuard Web Filtering URL cache depends on the amount of memory allocated for the cache as well as the size of the URLs in the cache. Administrators have no control over URL size, but you can adjust the size of the cache.
By default FortiGate units set aside 2 percent of total memory for the URL cache. From the FortiOS v3.0 CLI you can use the following command to adjust percent of total memory used by the cache to between 1 and 15 percent.
config webfilter fortiguard set cache-mem-percent <percent_integer>
end
where <percent_integer> can be 1 to 15 percent. The default value is 2 percent.
In a typical enterprise environment with cache-mem-percent set to the default value, a FortiGate-3000 unit or FortiGate-3600 unit URL cache can contain up to 100,000 URLs. In an environment such as this, the cache hit rate is typically around 45-50%.
The number of URLs that can be cached and the hit rate is expected to increase significantly in future FortiOS v3.0 maintenance releases.
