On Tue, 25 Aug 2009 21:11:53 +0200, mickymax@xxxxxx wrote: > Hi, > > I am trying to fully understand the refresh algorithm Squid is using: > > FRESH if expires < now, else STALE > STALE if age > max > FRESH if lm-factor < percent, else STALE > FRESH if age < min > else STALE > > I disabled the last-modified header on my apache server for an objekt > test.html for testing purposes. > My refresh_pattern looks like this: > refresh_pattern test3 10 10% 300 > > If I request something like > echo -e "GET http://example.com/test.html HTTP/1.0\n\n" | netcat > example.com 80 > > the answer from squid is > HTTP/1.0 200 OK > Date: Tue, 25 Aug 2009 19:01:46 GMT > Server: Apache/2.2.6 (Unix) PHP/5.2.5 > ETag: "4d04f6-2-f4490a00" > Accept-Ranges: bytes > Content-Length: 2 > Content-Type: text/html > Age: 346 > X-Cache: HIT from example.com > Via: 1.0 example.com (squid/3.0.STABLE18) > Connection: close > > > It is strange to me that Squid always produces a hit. Since the object does > not have a last-modified or expires header, the Squid algorithm should look > simply like this: > STALE if age > max > FRESH if age < min > else STALE > > But both: age>max and age < min do not work (no refresh of the object is > done via Squid), Squid is still caching the object. It only changes if I > set percent to 0%, then I receive a MISS, but percent should not be used > (since no last-modified-header), should it? > > I would appreciate any explanations. Sounds a bit like bug #7 being hit. Also check your access.log to see what type of HIT it is. You may be getting TCP_REFRESH_HIT (server IMS queried and it replied 'object not changed') instead of TCP_HIT (object from cache, no backend contact). Bug #7 means the old headers can get sent on the first case. Amos
