[CentOS] squid HA failover?

Les Mikesell lesmikesell at gmail.com
Fri Feb 6 22:12:35 UTC 2009


J Potter wrote:
> Assuming server A with IP M, server B with IP N, and DNS entry X  
> currently pointing at IP M:
> 
> 1) Add heartbeat on servers A and B, with heartbeat managing a new IP  
> address O (this is your virtual IP -- nothing to do with VRRP, that's  
> for your routers to failover your gateway).

Thanks - I know vrrp is different (and compatible with routers and other 
devices) but I thought it should work as an alternative.

> If you want active-standby on your squids, then have both squids bind  
> to 0.0.0.0 and you're done. The standby server will have squid  
> listening to requests, but since standby won't have the VIP O, it'll  
> just sit there. In this setup, heartbeat is only managing the VIP, but  
> no services.

Yes, I normally want one server handling the full load to maximize the 
cache hits.  But the other one should be up and running.  And, because 
this is already in production as a mid-level cache working behind a 
loadbalancer, I would like to be able to keep answering on the M or N 
addresses, gradually reconfiguring the web servers in the farm to use 
address O instead of the loadbalancer VIP address.  I got the impression 
from some of the docs/tutorials that it was a bad idea to access the M/N 
addresses directly.  Or does that only apply to services where it is 
important to only have one instance alive at a time or where you are 
replicating data?  Even after converting all of the farm to use the new 
address, I'll still want to be able to monitor the backup server to be 
sure it is still healthy.

-- 
   Les Mikesell
    lesmikeell at gmail.com




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