This directive defines an upper limit on the number of file descriptors that Squid should open for reading and writing cache files on disk. It is relevant for only the ufs and aufs storage schemes. It is a relatively simple hack for measuring the level of Squid’s disk activity. Experience shows that performance degrades significantly when Squid hits a filesystem bottleneck.
If Squid reaches this limit, it doesn’t attempt to store
subsequent cachable responses. Each time that happens, Squid
no.too_many_open_files counter (see Section 22.214.171.124). Note
that hitting this limit has a negative impact on your hit ratio. You
can monitor the number of open disk files by requesting the
info page from the cache manager (see Section 126.96.36.199).
If you set this directive to
0, Squid doesn’t place any limits on the
number of open disk file descriptors.