Re: [squid-users] Squid cluster - flat or hierarchical

> Hi,
>
> My loadbalancing is handled very well by LVS. My caches are using
> unicast ICP with the no-proxy option for their cache_peer's. I don't
> think Carp or round robin anything would help me much. My concern is
> whether or not my caches performance could suffer from forwarding
> loops if they are all siblings of each other? Is it OK to ignore the
> forwarding loop warnings in cache.log?

I'm not entirely sure. The warning appears when a request is dropped due
to the VERY nasty routing situation.
You may need to tweak the options a bit to remove them for siblings.
As an educated guess I'd expect digests etc to be leading to some of the
loops. As peer A tells peer B that peer C has access to it, when peer C
actually gets it from peer A etc.
Still tweaking a flat heirarchy to work as a cloud is harder than using a
efficiency-designed algorithm.

You WILL need some default for going direct though. Either to a default
parent, or allow_direct permissions.

Amos

>
> On Nov 6, 2007 7:29 AM, Amos Jeffries <squid3@treenet.co.nz> wrote:
>>
>> John Moylan wrote:
>> > Hi,
>> >
>> > I have 4 Squid 2.6 reverse proxy servers sitting behind an LVS
>> > loadbalancer with 1 public IP address. In order to improve the hit
>> > rate all 4 servers are all peering with eachother using ICP.
>> >
>> >
>> > squid1 -> sibling squid{2,3,4}
>> > squid2 -> sibling squid{1,3,4}
>> > squid3 -> sibling squid{1,2,4}
>> > squid4 -> sibling squid{1,2,3}
>> >
>> > This works fine, apart from lots of warnings about forwarding loops in
>> > the cache.log
>> >
>> > I would like to ensure that the configs are optimized for an up and
>> > coming big traffic event.
>> >
>> > Can I disregard these forwarding loops and keep my squids in a flat
>> > structure or should I break them up into parent sibling relationships.
>> > Will the forwarding loop errors I am experiencing cause issues during
>> > a quick surge in traffic?
>> >
>>
>> The CARP peering algorithm has been specialy designed and added to cope
>> efficiently with large arrays or clusters of squid.
>>
>> IFAIK it's as simple as adding the 'carp' option to your cache_peer
>> lines in place of other such as round-robin.
>>
>> http://www.squid-cache.org/Versions/v2/2.6/cfgman/cache_peer.html
>>
>> Amos
>>
>
Received on Tue Nov 06 2007 - 17:11:05 MST