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

But why would Squid even issue an "If-Modified-Since" to origin server if the min value is set to 5 days? Would this object not be seen as fresh and would just be served up by Squid as a TCP_HIT?

----- 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 7:19:51 PM
Subject: Re: [squid-users] Objects Release from Cache Earlier Than Expected

I am talking about If-Modified-Since between Squid and the web server,
not browser<->squid.

On ons, 2008-10-22 at 17:57 -0700, BUI18 wrote:
> 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 - 02:27:45 MDT