Squid / OS interaction

Filesystem

Squid currently stores one cache object per file
Squid hashes the directory name
/cache/dir/aa/bb/aabbccdd
Disk IO is currenly done in 4k chunks
Modern FSes aren't _too_ bad, but there's lots of room to grow!
Cache-oriented filesystems (eg COSS) are in development
Squid will shed filesystem operations to deal with load spikes
Evident by TCP_SWAPFAIL_MISS in access.log
Limit is generally configurable
squid_max_disk_fds can also impose a total limit of disk IO