Question about key_zone in proxy_cache_path

[Sven 'Darkman' Michels]

Hi,

The wiki (1) states:
"Zone size should be set proportional to number of pages to cache. The size of the
metadata for one page (file) depends on the OS; currently it is 64 bytes for
FreeBSD/i386, and 128 bytes for FreeBSD/amd64."

So for 10.000 files i would need roundabout 1,3meg of key_zone, and for example
1mio files would need 122meg, is it that easy?

Another question would be, if i set it to big, will it hurt performance? I already
had the key_zone set to small so nginx complained about and it looked like it
stopped serving new data.

Thanks and regards,
Sven

1: http://wiki.nginx.org/HttpProxyModule#proxy_cache_path