Re: [squid-users] refresh_pattern >>AND<< reload-into-ims

On 22/08/2013 4:37 a.m., HillTopsGM wrote:
> I have read what . . .
>
> reload-into-ims
>
> . . . is supposed to mean here:
> http://www.squid-cache.org/Versions/v3/3.1/cfgman/refresh_pattern.html
> <http://www.squid-cache.org/Versions/v3/3.1/cfgman/refresh_pattern.html>
>
> Basically this is all that it says:
>
> (QUOTE)
> reload-into-ims changes client no-cache or ``reload''
> to If-Modified-Since requests. Doing this VIOLATES the
> HTTP standard. Enabling this feature could make you
> liable for problems which it causes.
> (END QUOTE)
>
> I am trying to understand what it is doing with respect to the FAQ's tips on
> code to add to your squid.conf file that will help cache Windows Updates.
>
> That code is given here:
> http://wiki.squid-cache.org/SquidFaq/WindowsUpdate
> <http://wiki.squid-cache.org/SquidFaq/WindowsUpdate>
>
> . . . and a sample of one of the refresh_pattern lines from that page is
> this:
>
> refresh_pattern -i microsoft.com/.*\.(cab|exe|ms[i|u|f]|asf|wm[v|a]|dat|zip)
> 4320 80% 43200 reload-into-ims
>
> *Question 1:* Could someone please clarify what the system is going to be
> 'thinking' with this code?

If the client sends a request forceing cache reload
(Cache-Control:max-age=0) or requesting a revalidation
(Cache-Control:no-cache) Squid will send a IMS revalidation upstream
based on the stored object instead of properly relaying the clients
request Cache-Control header and updatign its cache with the results.

>
> *Question 2:* My understanding of windows updates is that '/An update, is
> an Update/'. Why would I set a limit on a cached update to 30 days (43200)?
> Why would I not make that number equivalent to 3 or 4 years (or more); is
> each windows update that you download not its own entity, never to be
> changed - /except to be updated by a future update/?

Most clients update within 30 days of the patch-tuesday releases. This
encourages caching for the peak load period and lets later clients get
the slower MISS.
You can set it to whatever to want.
3-4 years is not really worth doing as the service pack releases roll-up
the existing small updates. The cache is unlikely to have any content
older than 30 days anyway.

Amos
Received on Thu Aug 22 2013 - 03:07:10 MDT