Re: [squid-users] inconsistent caches using a sibling cache hierarchy

From: Matus UHLAR - fantomas <uhlar@dont-contact.us>
Date: Tue, 30 May 2006 09:43:35 +0200

On 29.05.06 22:20, Domingos Parra Novo wrote:
> I'm using a pool of (4) squid servers as a web accelerator for a slow
> backend (vignette, to be more exact). Right now, almost everything works
> like a charm, besides one thing.

> If, for any reason (high load, for example), a purge request (for object
> "foo") reaches servers 1, 2 and 3 (but haven't got the time to purge the
> object on server 4), and a new request for the object "foo" arrives on
> server 1 (which already expired this object), the request is redirected
> from server 1 to server 4 (which contains an old version of the object).
> In a few words, I sometimes get a invalid cache, with old objects on my
> squid servers.

does your backend web server provide correct expiry informations? Does it
provide correct Cache-Control: headers?

I think the main problem is that your caches provide old content, it has
nothing to do with their ICP communication.

> By the way, would htcp help me on this task? I know its "smarter" then
> ICP, but I haven't seen much documentation about any of them, to tell you
> the truth.

I don't think so, however HTCP is not fully supported in squid and afaik
it currently provides no more functionality than ICP.

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Received on Tue May 30 2006 - 01:43:41 MDT

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