cache cluster

From: Ronald Warner <cscrw@dont-contact.us>
Date: Wed, 14 Jun 2000 09:36:15 +0800

We are using two squid2.3stable1 (same squid.conf) cache servers
and one squid/1.1.20 cache server (more or less the same). We
have it configured to be a cache cluster in our DNS.

I have been reading the following url:
http://www.squid-cache.org/Doc/Users-Guide/opt/performance.html
and got interested in the following statements:
"Object A is on cache1. A user wants to download this object, but
in this case he connects to cache2 (this is because of the random
rotation of the caches). He hits 'shift-reload' on the page though, so
the browser tells cache2 don't give me this from disk. Since this
header is present in the request, cache2 goes directly to the origin
server and downloads another copy, rather than checking with its
siblings. There are thus 2 copies, one in cache1 and one in
cache2.
        Note that this can cause problems when there is an object that
you want to force the expiration of (such as a page that you have
updated or is corrupt). Hitting shift-reload won't clear the object
from EVERY cache, since the next person to come along may hit
cache2 when you cleared the object from cache1. Caches querying
each other don't download the newest object from their sibling
caches, they simply get them from the one that responds fastest.
You should use the cachemgr.cgi script to clear the objects from
each and every cache, one by one."

Is this still true for the the newer versions of squid?

Thanks.
Received on Tue Jun 13 2000 - 19:26:07 MDT

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