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From Szymon Francuzik <>
Subject Re: Cache problems
Date Mon, 12 Jul 2010 12:56:46 GMT
On 09.07.2010 16:37, Leif Hedstrom wrote:
>> On 07/09/2010 03:47 PM, Jason wrote:
>>  Can you try testing a static page (html) and limiting your connects
>>  to 1-10 so you can debug at least.
I tried testing a static page and it's worked ok (page is cached after 
first request).

> I addition to what Jason said, a few things to try:
> 1) Make sure traffic_cop isn't killing traffic_server.  I had this 
> happen to me once, and it shows up as if the cache is blown away 
> (because the directory is never flushed to disk). This could happen if 
> the health check from traffic_cop to traffic_server fails. This is 
> easy to see, for example, just check the "start" time of 
> traffic_server vs traffic_manager (they should usually be the same).
traffic_server works all the time. traffic_server, traffic_cop and 
traffic_manager have the same start time.
> 2) I'd really like to see the complete header from the Origin server, 
> to make sure there is nothing in the response that prevents TS from 
> caching the response.

Header from the origin server (for dynamic page):

HTTP/1.1 200 OK
Date: Mon, 12 Jul 2010 12:20:04 GMT
Server: Apache/2.2.15 (Unix)
Content-Type: text/html; charset=utf-8

Header from  the origin server for static page (cached after first 

HTTP/1.1 200 OK
Date: Mon, 12 Jul 2010 12:20:08 GMT
Server: Apache/2.2.15 (Unix)
Last-Modified: Mon, 12 Jul 2010 09:58:50 GMT
ETag: "48a4e2-2aabd-48b2dcca50a80"
Accept-Ranges: bytes
Content-Length: 174781
Content-Type: text/plain

TS doesn't use ETag (even if I replace static page, ts responses with 
cached version). It looks like 'Last-Modified' is crucial. We set 
attributes proxy.config.http.cache.required_headers INT 0 and 
proxy.config.http.cache.when_to_revalidate INT 3 (never stale), so we 
didn't expect this header to be required by TS.

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