Re: Squid problem?

From: Michael Pelletier <>
Date: Wed, 30 Jul 1997 10:54:24 -0400 (EDT)

On Wed, 30 Jul 1997, Leigh Porter wrote:
> I just tried a www site that has multiple IP addresses. I try the site
> form machine A and find it works fine, then from machine B, an IE4 thing
> with WinNT 4 the sire returns server busy (on a differant IP address).
> I click reload on this system and I get server busy again even though on
> another system, putting that IP address in gives the page OK - the Squis
> box had cached the server busy page!
> It should not do that, so I believe because I set
> httpd_accel_uses_host_header on in squid.conf and so it should go on the
> hostname instead according to what I have seen in the list over the past
> day or so.
> Anybody know whats happeneing here?

Squid, by default, does not retry a site that refuses its connection, even
if it has multiple IP addresses that might represent mirror servers, like
the site. The first address that refuses will return an
error to the user, but will also be ejectec from the IP cache so clicking
reload gives you a chance to retrieve the page.

Out of necessity, since many users here access the Microsoft pages, I
wrote up a patch to make Squid retry multi-address hosts as many times as
there are addresses, and to retry single-address hosts up to three times

It also keeps track of ok/bad addresses rather than ejecting the bad ones
from the cache, and if all addresses are marked bad, it will retry them
once again as a last resort before returning an error to the user, since
one of the other "bad" addresses might have had its load reduce far enough
that it can accept requests again. (My IP cache hit rate is 97.5%.)

The latest known-good version of the patch is 1.1.10, I've been having a
number of segmentation fault problems with the 1.1.14 version, even though
it's implemented in exactly the same way. I'm working on tracking that
down now, and you should use the 1.1.14 version of the patch at your own
risk with preparations in place to fall back if needed.

The patches are at:

And I'm currently running the 1.1.10 version on, and if
you wish you can check out the IP cache info, since the cachemgr.cgi does
not need a password for that and a few other functions.

        -Mike Pelletier.
Received on Wed Jul 30 1997 - 07:59:20 MDT

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