Dingwell, Robert A. wrote:
On 3/26/09 11:01 AM, "Dingwell, Robert A. (BOBD)" <bobd@xxxxxxxxx> wrote:
I¹ve been trying to get a caching architecture setup so that if a server I
am caching content for goes down or is more likely just unavailable to do
network issues I can have the cache serve up the stale content. In the
production environment that this will be used I will not have the ability to
have all of the services involved set cache control headers on their data. We
are operating on a wan with people all over the globe so it would be really
difficult to get everyone to do that. What I can do though is to make sure
that everything goes through apache acting as a reverse proxy which then sets
the Cache-Control header, which I have done and verified that it does indeed
do what I want it to.
So now I fire up squid and apache and attempt to access a server I have
control over and I get back the data I expect to get back. Look in the squid
log file see the header in the log ³Cache-Control: stale-if-error=300² so I
know it¹s being sent. Now I shutdown the server I just accessed and attempt
to access the same url. I expect to get back the same data that I just got
back but instead I get back the error page saying the service is unavailable.
Shouldn¹t squid be serving up the stale content? Or am I missing a step. The
other odd thing is once I start the server back up it takes a couple of
minutes to get back the page from server as squid seams to be caching the
error page.
I know that stale-if-error is only going to work for 500-504 errors but
looking through the squid logs again I see that I am getting an error code
back when I try to access the page when it¹s down ³HTTP/1.1 503 Service
Temporarily Unavailable².
One last thing this article , http://www.mnot.net/blog/2007/12/12/stale ,
makes it sound like squid has a configuration parameter that is used to enable
stale-if-error even when the server does not send the control header. Does
anyone know if this exists or what the magic incantation is to get it working?
Anybody have any ideas as to what I may be doing wrong, or an alternative
approach to accomplishing what I am trying to get working? I already tried
using offline mode which did not work and I think isn¹t really what I would
want to do anyway as I need squid to attempt to access the server and serve up
the stale data only when the server is down.
Any help is appreciated ,
Thanks
Rob
Depends.
Squid-2.7 supports it, the others do not yet though there is a patch for
Squid-3.1 in bugzilla awaiting someone to test it properly.
Amos
--
Please be using
Current Stable Squid 2.7.STABLE6 or 3.0.STABLE13
Current Beta Squid 3.1.0.6
