Re: AW: [squid-users] detecting dead parent problem - understanding parent and icp

Hey Markus,

What is the problem you are facing again?
are you trying to detect whether the proxy is working or not??
do you want 4 proxies to be in fail-over mode??? for HA??
I would imaging you have a PC and on it 4 proxies as cache_peers and you
would like to not have an option for a connection to be down??
If do and it's on a PC then what version of squid are you using?
ICP is not to detect if the proxy is up but to *know* if the proxy has
the specific cache object in case it's on one of the 4 the request would
pass thorough it.
there is another option that existed on squid 2.X that checks if the
cache_peer is up.
I built a helper that can help you detect if there is a problem in on of
the cache_peers to minimize the downtime to very very low.
https://github.com/elico/squid-helpers/tree/master/squid_helpers/proxy_hb_check

the above link contains the helpers which are very simple but are not
optimized for very high-load.
You can optimize the usage of a similar helper when used with squid
internal ttl for 2 secs and use the src IP instead of the url which is
changing all the time.

If you have more questions feel free to continue this thread.
If you have an idea on how to integrate the feature into squid many will
be happy.

Best Regards,
Eliezer

On 07/03/2013 01:29 PM, Rietzler, Markus (RZF, SG 324 /
<RIETZLER_SOFTWARE>) wrote:
> i will come back to this subject, as the problems prevent from updating our systems. as said, we have a loadbalancing/fallback setup with 4 central proxy servers and two dmz proxy servers.
>
> you suggest removing no-query from cache-peer. we have setup our proxy servers without any icp/icmp. so removing no-query will make no difference as our parent proxies don't listen on icp queries.
>
> one question: as said we don't use ICP in our proxies. our setup is as follow:
>
> PC - proxy_user - proxy_inter1 -
> - proxy_inter2 - proxy_dmz1
> - proxy_inter3 - proxy_dmz2
> - proxy_inter4 -
>
> clients connect to proxy_user. we have defined 4 parent proxies. those 4 parent proxies will also have two parent proxies setup, those two dmz-proxies will then make the real request in the internet.
>
> none of our proxies will use icp. what will we gain with activating icp? could the missing icp be one reason for the performance problem when stopping 2 of the 4 proxy_inter? will there be a problem in detecting DEAD parents without icp?
>
> as far as I understood: icp will give me some benefit when proxy_user don't have the requested object. in our setup it will have to query eg. proxy_inter1 (based on sourcehash). if proxy_inter1 has the object good, if not proxy_inter1 will fetch it. with icp proxy_user will first do an icp query to all of the 4 proxy_inter to see I one of them have the object. if one says "have it" then it will receive the object from eg. proxy_inter3 although sourcehash would normally fetch from proxy_inter1. is this right?
>
>
> markus
Received on Wed Jul 03 2013 - 11:16:04 MDT