[squid-users] pages not held in cache

I have a problem. It seems that objects are getting swapped out very
quickly. Below is an example of 2 requests for the same page within
seconds of each other. The first shows that the Age of the file is 10
seconds, and should be cached. The second request shows that it wasn't
found in the cache. Could this be related to the amount of disk space
given to the cache? Are there any other things I can look at?

   Expires: Fri, 06 Sep 1996 11:12:19 GMT
   Vary: Accept-Encoding
   Last-Modified: Fri, 01 Sep 2006 23:04:03 GMT
   Cache-Control: max-age=0, s-maxage=7200, must-revalidate
   Content-Type: text/html;charset=utf-8
   X-Header-Set-Id: cache-in-proxy-1-hour
   Age: 10
   X-Cache: HIT from xxx.org
   X-Cache-Lookup: HIT from xxx.org:80
   Connection: keep-alive
Length: 35,190 (34K) [text/html]

------

   Expires: Fri, 06 Sep 1996 11:12:32 GMT
   Vary: Accept-Encoding
   Last-Modified: Fri, 01 Sep 2006 23:04:03 GMT
   Cache-Control: max-age=0, s-maxage=7200, must-revalidate
   Content-Type: text/html;charset=utf-8
   X-Header-Set-Id: cache-in-proxy-1-hour
   X-Cache: MISS from xxx.org
   X-Cache-Lookup: MISS from xxx.org:80
Received on Mon Sep 04 2006 - 05:39:19 MDT