Re: [squid-users] prevent attempts to go outside for any noncached objects during offline_mode on

On 10.09.2012 23:48, Oguz Yilmaz wrote:
> Hi,
>
> I have read on working of offline_mode in the list. It is an
> aggressive caching parameter which prevent refreshing of already
> cached object and gives from the cache. However, if the object is not
> cached, it try to look for the object thru direct or cache peer. Do
> you have any suggestions for implementing a "completely offline"
> state
> with current squid parameters to prevent attempts to get uncached
> objects, also

offline_mode is very badly named. It does not mean *offline* at all.

What it does is enable an extra-greedy caching policy to preserve data
in cache even if it is very likely to be replaced immediately on next
request (normally Squid tries to ignore these to save on disk I/O load).

Since squid-2.6 the particular actions which offline_mode used to be
needed for in 2.5 and older have been slowly made into defaults and
obsoleted by HTTP/1.1 performance features. The only remaining use for
offline_mode is to ensure that *everything* gets added to cache; for
example prior to a planned parent web server outage/upgrade so that the
reverse-proxy can service the site(s) while *that* server is offline.

For preventing clients getting MISS traffic use miss_access (ie
"miss_access deny all" is what you describe above). Squid will still
require network access for DNS etc, but the requests matching your
miss_access ACLs won't get served any non-cached responses.

Amos
Received on Mon Sep 10 2012 - 23:19:27 MDT