Hi, We are running Squid 2.5.STABLE3 version in http accelerator mode on a dedicated Red Hat EL 3.0 server. These are the settings for the size of the cache on the disk and in the memory: cache_dir ufs /spare/squid 7000 16 256 cache_mem 2 GB The number of users at the pick is around 2000. We expect the number of the users is going to increase in the future significantly. I wonder if there is any way to estimate the number of file descriptors for Squid based on the number mentioned above. Also, I checked /usr/include/bits/types.h file looking for the definition of __FD_SETSIZE. I could not find it. I assume I would need to define this variable before compiling Squid. Am I right? Thanks, Dimitar