Re: [squid-users] 2 node squid cluster

Anyone .. ? Bottomline question is: Why doesn't ICP work with stale, expired
pages ?

Regards,

Marc

----- Original Message -----
From: "Marc" <squid_at_cornholio.nl>
To: <squid-users_at_squid-cache.org>
Sent: Wednesday, February 11, 2009 7:29 PM
Subject: [squid-users] 2 node squid cluster

> Hi,
>
> I'm struggling with the following;
>
> What I would like to set up is a redundant pair of squid servers as a
> frontproxy accelerator for my web servers. I also would like to set this
> up so that squidserver1 checks with squidserver2 if it has a 'fresh' page
> before consulting the backend webserver. But of course, to prevent loops,
> if squidserver2 doesn't have the page it shouldn't try to resolve it,
> squidserver1 should get the page from the backend itself.
>
> Now I came a long way. In fact, I think I'm close (but yet so far..).
>
> I tried to set this up with siblings. So the part that matters from my
> squid configuration (on both squids):
>
> http_port squid-test:80 vhost
> icp_port 3130
> udp_incoming_address squid-test
> cache_peer sibling-test sibling 80 3130
> login=PASS
> cache_peer backend-test parent 80 0
> originserver no-query login=PASS
>
> In the hostsfile of squidserver1 sibling-test resolves to squidserver2 and
> vice versa. squid-test resolves to the local ip address, backend-test
> resolves to the webserver. Now this works exactly like I'd want it to work
> for pages that have not been in the cache. However if a page has been in
> the cache but is stale, then the sibling is never consulted. So here goes,
> first 3 working scenario's to show how far I've got, and finally the
> scnenario I'd like to solve:
>
> Scenario 1 (expected):
> squidserver1: page is fresh
> squidserver2: page is fresh
> - Client requests the page from squidserver1
> - Squidserver1 detects the page is fresh and delivers it to the client
>
> Scenario 2 (expexted):
> squidserver1: page is not present in the cache
> squidserver2: page is fresh
> - Client requests the page from squidserver1
> - Squidserver1 detects the page is not present in the cache
> - Squidserver1 sends an ICP request to squidserver2 to check if it has a
> fresh copy of the page
> - Squidserver2 replies with ICP_HIT
> - Squidserver1 requests the page from squidserver2
> - Squidserver1 receives the page from squidserver2, stores it locally and
> delivers it to the client
>
> Scenario 3 (expexted):
> squidserver1: page is not present in the cache
> squidserver2: page is expired
> - Client requests the page from squidserver1
> - Squidserver1 detects the page is not present in the cache
> - Squidserver1 sends an ICP request to squidserver2 to check if it has a
> fresh copy of the page
> - Squidserver2 replies with ICP_MISS
> - Squidserver1 consults the backend webserver for the page
> - Squidserver1 receives the page from the backend, stores it locally and
> delivers it to the client
>
> Scenario 4 (strange):
> squidserver1: page is stale
> squidserver2: page is fresh
> - Client requests the page from squidserver1
> - Squidserver1 detects the page is expired
> - Squidserver1 *DOES NOT* send an ICP request to squidserver2 to check if
> it has a fresh copy of the page (it sends nothing to squidserver2, also
> checked with tcpdump)
> - Squidserver1 consults the backend webserver for the page
> - Squidserver1 receives the page from the backend, stores it locally and
> delivers it to the client
>
> Logging of squidserver1 during Scenario 4 shows that it does not see any
> neighbors:
> 2009/02/09 13:06:21| neighborsCount: 0
> 2009/02/09 13:06:21| peerSelectIcpPing: counted 0 neighbors
> I can assure you however that the neighbor is there, I've tested all 4
> scenario's multiple times.
>
> So, I'd like to solve Scenario 4. What did I miss ?
>
> If you'd like more information let me know.
>
> Thanks!
>
> Marc
>
Received on Wed Mar 04 2009 - 10:27:11 MST