Re: [squid-users] Set up a cluster of 10 squid servers using ~170GB of memory and no disk

From: Jérôme Loyet <>
Date: Wed, 2 Oct 2013 12:24:53 +0200

thx for your reply amos

2013/10/2 Amos Jeffries <>:
> On 2/10/2013 10:02 p.m., Jérôme Loyet wrote:
>> Hello,
>> I'm facing a particular situation. I have to set-up a squid cluster on
>> 10 server. Each server has a lot of RAM (192GB).
>> Is it possible et effective to setup squid to use only memory for
>> caching (about 170GB) ?
> memory-only caching is the default installation configuration for Squid-3.2
> and later.

is there any problem by setting cache_mem to 170GB ?

>> What directive should be tweaked ? (cache_mem,
>> cache_replacement_policy, maximum_object_size_in_memory, ...). The
>> cache will store object from several KB (pictures) up to 10MB (binary
>> chunks of data).
> All of the above memory cache parameters. (cache_replacement_policy is disk
> parameter, but there is memory_cache_replacement_policy instead).
> cache_mem and maximum_object_size_in_memory in particular. The default is
> for only small objects to be memory cached.
>> With 10 sibling cache squid instances, what should I use as type of
>> cache peering ? (10 siblings or a multicast ICP cluster, other ?)
> With memory cache holding under-32KB objects SMP workers would be best. They
> share a single memory cache, but it is size limited to 32KB memory pages due
> to Squid internal storage design. I'm not sure yet whether the work underway
> to extend Rock storage past this same limit is going to help shared memory
> cache as well (hope so, but dont know).

I'm planning to set up one squid instance on each of the 10 servers.
As the server won't be dedicated to squid, I want to limit squid to
run on one single process (no SMP).

> For now, if you want larger objects to server from memory you will be best
> off with a CARP cluster or HTCP sibling configuration for now.
> NP: I recommend staying away from ICP with Squid-3.2 and later. We have not
> yet changed the defaults, but ICP has a very high false-positive hit rate on
> HTTP/1.1 traffic. HTCP is more bandwidth hungry on the UDP but far better on
> HIT rate.

what's your opinion about multicast for sharing cache ?

> Amos
Received on Wed Oct 02 2013 - 10:25:10 MDT

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