Re: [squid-users] Objects Release from Cache Earlier Than Expected

From: Henrik Nordstrom <henrik_at_henriknordstrom.net>
Date: Thu, 23 Oct 2008 01:06:33 +0200

On ons, 2008-10-22 at 14:35 -0700, BUI18 wrote:

> Object is initially cached. Max age in squid.conf is set to 1 min.
> Before 1 min passes, I request the object and Squid returns TCP_HIT.
> After 1 min, I try to request for object again. Squid returns
> TCP_REFRESH_HIT, which is what I expect. I leave the entire system
> untouched. A day or a day and a half later, I ask for the object
> again and Squid returns TCP_REFRESH_MISS/200.

TCP_HIT is a local hit on the Squid cache. Origin server was not asked.

TCP_REFRESH_HIT is a cache hit after the origin server was asked if the
object is still fresh.

TCP_REFREHS_MISS is when the origin server says the object is no longer
fresh and returns a new copy on the conditional query sent by the cache.
(same query as in TCP_REFRESH_HIT, different response from the web
server).

> What could possibly cause Squid to refetch the entire object again?

A better question is why your server responds with the entire object on
a "If-Modified-Since" type query if it hasn't been modified. It should
have responded with a 304 response as it did in the TCP_REFRESH_HIT
case.

Regards
Henrik

Received on Wed Oct 22 2008 - 23:06:40 MDT

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