Re: expiry and ims question

dean.scothern@wwgsolutions.com wrote:

> Well it doesn't always update correctly and I'm pulling my hair out to
> work out why.

The default config considers objects fresh for 20% of their age. Age
calculation depends on the clock being reasonably correct on your web
server and Squid.

> I thought that this sort of thing was automatic, and that squid does a ims check
> with the web server.

Only if the object isn't considered fresh.

> The squid cache has one sibling for the domain, is this important?.

It could be. If that sibling has tuned their freshness heuristics to
more aggressive caching then the result may be confusing, or if the
clock is skewed.

If you investigate the returned object headers you should be able to
understand much better what is going on. Headers to look closer at is
Date, Age and X-Cache*.

The headers can easily be retreived by using the client command

client -m HEAD http://your.server/path/to/file
(full option usage: client -h)

--
Henrik Nordstrom
Squid hacker