[squid-users] Diagnosing Objects That Are Not Cached (squid/3.0.STABLE8)

Although my squid server is only supporting three users, I am pleasantly surprised at the percentage of traffic handled by the cache. However, I think I can do better. Scanning the logs, I noticed a number of cases where the same files were resulting in a TCP_MISS/200 condition. A lot are due to '?'-strings in the URL, even though the content is not always dynamic (I am researching options). However, I see a fair number of cases where I would expect the object to be cached. Is there a process for diagnosing why squid thinks the object is not cache-able?

For example, from the access.log and store.log files:

1265776256.982 3934 10.1.2.123 TCP_MISS/200 861 GET http://www.facebook.com/images/loaders/indicator_blue_small.gif - DIRECT/66.220.146.18 image/gif
1265776281.912 370 10.1.2.123 TCP_MISS/200 861 GET http://www.facebook.com/images/loaders/indicator_blue_small.gif - DIRECT/66.220.146.18 image/gif
1265776294.352 407 10.1.2.123 TCP_MISS/200 861 GET http://www.facebook.com/images/loaders/indicator_blue_small.gif - DIRECT/66.220.146.18 image/gif

1265776256.982 RELEASE -1 FFFFFFFF 54F74EF7200473A70B1E94F452E355C0 200 -1 -1 1265776256 image/gif 522/522 GET http://www.facebook.com/images/loaders/indicator_blue_small.gif
1265776281.912 RELEASE -1 FFFFFFFF D50A66A7F3C5E849631BF132637A99A3 200 -1 -1 1265776281 image/gif 522/522 GET http://www.facebook.com/images/loaders/indicator_blue_small.gif
1265776294.352 RELEASE -1 FFFFFFFF 25AA53B40429083AF5B68BAF4A663EF0 200 -1 -1 1265776294 image/gif 522/522 GET http://www.facebook.com/images/loaders/indicator_blue_small.gif

redbot.org returns:

HTTP/1.1 200 OK
    Accept-Ranges: bytes
    Cache-Control: max-age=2592000
    Content-Type: image/gif
    Expires: Sat, 13 Mar 10 22:37:08 GMT
    X-Cnection: close
    Date: Thu, 11 Feb 2010 22:37:08 GMT
    Content-Length: 522

General: The Expires header's value isn't a valid date.The Content-Length header is correct.The server's clock is correct.
Caching: This response can be stored by any cache.This response is fresh until 4 weeks 2 days from now.This response can be served stale.
Partial Content: A ranged request returned the full rather than partial content

I am using a fairly vanilla squid.conf file, with the exception of some ad-blocking:

#Suggested default:
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern (cgi-bin|\?) 0 0% 0
refresh_pattern . 0 20% 4320

Any suggestions would be greatly appreciated!
         Thanks, Norbert
Received on Thu Feb 11 2010 - 23:12:02 MST