[squid-users] Incorrect content being return

Greetings from a new member of the list.

    I'm working with a medium-sized site that uses squid as a
transparent cache for its content. We are running squid-2.4.STABLE7 on
FreeBSD 4.0, and the squid servers are caching content for an array of
apache servers. The site is actually comprised of several sites, and we
notice that the squid servers for the largest site are sometimes
returning the wrong content. We believe (from looking at the apache
logs) that when this happens, the squids are actually asking the apache
servers for content using the wrong URL. We're seeing several million
page views per day; this sort of error seems to happen less than 30
times per day, and seems to resolve itself quickly (within 30 seconds)

    Some other facts about our squid servers that we believe might be
contributing:

        - Our larger sites have site a lot of content, so the squid
servers typically have about 200K-400K StoreEntries
        - Our squid servers have a pretty low cache hit ratio (we're
currently working to bring it up, but it's about 40-50% right now)
        - We have 6 squid servers proxying information that is contained
on 28 apache servers (we have a redirector program installed to point
the squid to the correct server). We are also suspicious of the
redirector; however, our redirector log files seem to indictate that the
redirector is working correctly; plus, we use the exact same redirector
on squid servers that don't seem to have the problem.

     What we have already done:
        - Instrumented the redirector to confirm that it's passing back
the correct values to squid
        - Reduced the size of the cache (this actually seemed to make
things worse)
        - Examined the squid logs and corresponding apache logs (this is
where we discovered that squid may be fetching content from the wrong
URL)

     What we are currently doing:
        - Further instrumenting the redirector
        - Trying to increase the disk space on the squids to increase
the cache-hit ratio
        - Trying to reduce the number of objects that each squid has to
cache

     I'd appreciate any comments on how to track the problem down
further or resolve it.

Best,

Jonathan
Received on Sun Jul 21 2002 - 22:37:21 MDT