But if I install 2 HAProxy as load balancers, doesn't one act as the primary
loadbalancer directing the load to the known servers while the secondary takes
over load distribution as soon as the heartbeat fails? I remember reading this.
Is this wrong?
________________________________
From: David Coulson <da...@davidcoulson.net>
To: Hermes Flying <flyingher...@yahoo.com>
Cc: Baptiste <bed...@gmail.com>; "haproxy@formilux.org" <haproxy@formilux.org>
Sent: Thursday, November 29, 2012 8:39 PM
Subject: Re: HAproxy and detect split-brain (network failures)
You are mixing two totally different things together.
1) HAProxy will do periodic health checks of backend systems you are
routing to. Depending if you configure something as 'backup' or 'not
backup' will determine if/how traffic is routed to it. The backend
systems do not 'take over'. Haproxy just routes traffic to systems
based on your configuration. The backend systems don't know/care
about the other backend nodes, unless your application requires it
which is a different story and nothing to do with haproxy. HAproxy
only cares about a single instance of itself - If you have more than
one haproxy instance, they do NOT communicate anything between each
other.
2) In terms of keepalived, pacemaker, etc, it makes no difference
which you use with haproxy - all they do is manage the IP
address(es) which haproxy is listening on, and perhaps restart
haproxy if it dies. Their configuration and how you maintain quorum
in a two-node configuration is a question for one of their mailing
lists, or just read their documentation. I personally use pacemaker.
On 11/29/12 1:35 PM, Hermes Flying wrote:
Well I don't follow:
>"You can have a pool of primary that it routes across, then backup systems
>that are only used when all primary systems are unavailable."
>When you are saying that "the backup systems that are used when primary
>systems are unavailable", how do they decide to take over? How do they know
>that the other systems are unavailable?
>Are you saying that they depend on third party components like the ones you
>mentioned (Keepalived etc)? In this case, what is the most suitable tool to be
>used along with HAProxy? Is there a reference manual for this somewhere?
>
>
>
>From: David Coulson mailto:da...@davidcoulson.net
>To: Hermes Flying mailto:flyingher...@yahoo.com
>Cc: Baptiste mailto:bed...@gmail.com; mailto:haproxy@formilux.org
>mailto:haproxy@formilux.org
>Sent: Thursday, November 29, 2012 8:21 PM
>Subject: Re: HAproxy and detect split-brain (network failures)
>
>
>HAProxy only does primary and backup in terms of active backend systems - You
>can have a pool of primary that it routes across, then backup systems that are
>only used when all primary systems are unavailable.
>
>There is no concept of a cluster in terms of haproxy
instances, although you can run more than one and
manage them via something like pacemaker, keepalived
or rgmanager.
>
>
>On 11/29/12 1:19 PM, Hermes Flying wrote:
>
>Hi,
>>From a quick look into HAProxy, I see that it is a Primary/backup
>>architecture. So isn't ensuring that both "nodes" don't become primary part
>>of HAProxy's primary/backup "protocol" ?
>>
>>
>>From: Baptiste mailto:bed...@gmail.com
>>To: Hermes Flying mailto:flyingher...@yahoo.com
>>Cc: mailto:haproxy@formilux.org mailto:haproxy@formilux.org
>>Sent: Thursday, November 29, 2012 3:02 PM
>>Subject: Re: HAproxy and detect split-brain (network failures)
>>
>>Hi,
>>
>>This is not HAProxy's role, this is the tool
you use to ensure high
>>availability to do that.
>>
>>I could see a way where HAProxy can report one
interface failing,
>>maybe this could help you to detect if you're
in a split brain
>>situation.
>>
>>cheers
>>
>>
>>
>>On Thu, Nov 29, 2012 at 11:51 AM, Hermes
Flying <flyingher...@yahoo.com> wrote:
>>> Hi,
>>> I am looking into using HAProxy as our
load balancer.
>>> I see that you are using a primary/backup
approach. I was wondering how does
>>> HAProxy (if it does) address split-brain
situation? Do you have a mechanism
>>> to detect and avoid it? Do you have some
standard recommendation to all
>>> those using your solution?
>>>
>>> Thanks
>>
>>
>>
>
>
>
