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

Henrik - Thanks for taking time out to respond to my questions. I'm completely stumped on this one.

In our production environment, we set min and max to 5 and 7 days, respectively.

As I understand it, if the request is made for the object in say....3 days or 4 days (less than 5 days), I would always expect a TCP_HIT.

But again, after 1 to 2 days, I see TCP_REFRESH_MISS and I get the whole object.

I thought that by setting the min to 5 days would guarantee freshness up to 5 days.

Do you know of a problem that maybe causes Squid to ignore the rules on determining whether an object is fresh?

We used fiddler and actually removed the "If-Modified-Since" part of the request and still we get TCP_REFRESH_MISS.

Do you have any other ideas on areas we might want to check to see what could possibly be causing this behavior?

Thanks

----- Original Message ----
From: Henrik Nordstrom <henrik_at_henriknordstrom.net>
To: BUI18 <lbui18_at_yahoo.com>
Cc: squid-users_at_squid-cache.org
Sent: Wednesday, October 22, 2008 4:06:33 PM
Subject: Re: [squid-users] Objects Release from Cache Earlier Than Expected

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 Thu Oct 23 2008 - 00:57:31 MDT