[squid-users] intermittent ERR_CANNOT_FORWARD

Hi,

I'm running Squid 2.6 STABLE12 as a reverse proxy. It is configured to
select one of two origin servers based on the request URL like this:

cache_peer 10.1.64.104 parent 8102 0 originserver no-query round-robin
cache_peer 10.1.64.106 parent 8105 0 originserver no-query round-robin

# always_direct = default
never_direct allow all

acl api_url urlpath_regex ^/api/*

cache_peer_access 10.1.64.104 allow api_url
cache_peer_access 10.1.64.104 deny all
cache_peer_access 10.1.64.106 allow !api_url
cache_peer_access 10.1.64.106 deny all

Currently only URLs that *do* match the api_url acl are ever sent to Squid.

After a power outage yesterday I started seeing "X-Squid-Error:
ERR_CANNOT_FORWARD 11" in the response headers of some but not all such
requests. I had no difficulty connecting directly to the origin server
at 10.1.64.104:8102. The errors went away as soon as I restarted Squid.

This raises the following questions:

1) Is it inappropriate to use the 'round-robin' option in this way,
since only one origin server peer will match the cache_peer_access rules
for a given URL?

2) Why did some requests succeed and some fail? Is there a health test
that blocks the opening of new connections but allows existing
persistent connections to be reused?

Does anyone have insight on these?

Thanks,
Ben
Received on Wed Jul 25 2007 - 13:32:46 MDT