Re: [squid-users] about the cache and CARP

From: Henrik Nordström <>
Date: Tue, 16 Aug 2011 23:27:11 +0200

tis 2011-08-16 klockan 16:54 -0400 skrev Carlos Manuel Trepeu Pupo:
> I want to make Common Address Redundancy Protocol or CARP with two
> squid 3.0 STABLE10 that I have, but here I found this question:
> If the main Squid with 40 GB of cache shutdown for any reason, then
> the 2nd squid will start up but without any cache.

Why will the second Squid start up without any cache?

If you are using CARP then cache is sort of distributed over the
available caches, and the amount of cache you loose is proportional to
the amount of cache space that goes offline.

However, CARP routing in Squid-3.0 only applies when you have multiple
levels of caches. Still doable with just two servers but you then need
two Squid instances per server.

* Frontend Squids, doing in-memory cache and CARP routing to Cache
* Cache Squids, doing disk caching

When request routing is done 100% CARP then you loose 50% of the cache
should one of the two cache servers go down.

There is also possible hybrid models where the cache gets more
duplicated among the cache servers, but not sure 3.0 can handle those.

Received on Tue Aug 16 2011 - 21:27:15 MDT

This archive was generated by hypermail 2.2.0 : Wed Aug 17 2011 - 12:00:02 MDT