Great help! Thank you for your time! Much appreciated!
________________________________
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 11:13 PM
Subject: Re: HAproxy and detect split-brain (network failures)
In general, yes, Pacemaker is reliable. If your config is wrong, you may still
have an outage in the event of a failure.
That said, if you are a business and need support, you probably want
to use whatever clustering software ships with the distribution you
use. I belive SuSE uses pacemaker, but RedHat still uses rgmanager.
Pacemaker is tech preview in RHEL6 but will be mainline in 7. I
believe RedHat employ some core developers of pacemaker.
David
On 11/29/12 4:10 PM, Hermes Flying wrote:
Thank you for your help.
>I take it that you are find Pacemaker reliable in your experience? Should I
>look into it?
>
>
>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 11:04 PM
>Subject: Re: HAproxy and detect split-brain (network failures)
>
>
>Again, you need to talk to the pacemaker people for actual clustering
>information.
>
>The ping was so a node could detect it lost upstream
connectivity, and move the VIP, otherwise the VIP may
continue to run on a system which does not have access
to your network. This has nothing at all to do with
split brain.
>
>If you want to deal with split brain, add a third node.
Period. You also want to have redundant heartbeat
communication paths. You also want STONITH/fencing so if
one node detects the other is down it'll power it off or
crash it. I've not had issues with a two-node cluster
with two diverse backend communication links and fencing
enabled.
>
>David
>
>
>On 11/29/12 3:58 PM, Hermes Flying wrote:
>
>"You can have pacemaker ping an IP (gateway for example) and migrate the VIP
>based on that"
>>How does this help for splitbrain?
>>If I understand what you say, pacemaker will ping an IP and if successfull
>>will assume that the other node has crashed. But what if the other node
>>hasn't and it is just their communication link that failed? Won't both become
>>primary?
>>How does the ping help?
>>
>>
>>
>>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 10:26 PM
>>Subject: Re: HAproxy and detect split-brain (network failures)
>>
>>
>>
>>
>>On 11/29/12 3:11 PM, Hermes Flying wrote:
>>
>>I see now!
>>>One last question since you are
using Pacemaker. Do you recommend it
for splitbrain so that I look into
that direction?
>>>
>>Any two node cluster has risk of split
brain. if you implement fencing/STONITH, you
are in a better place. If you have a third
node, that's even better, even if it does
not actually run any services beyond the
cluster software
>>
>>I mean when you say that pacemaker restart HAProxy, does it detect network
>>failures as well? Or only SW crashes?
>>>I assume pacemaker will be aware of
both HAProxy1 and HAProxy2 in my
described deployment
>>>
You can have pacemaker ping an IP (gateway for example) and migrate the VIP
based on that. In my config I have haproxy configured as a cloned resource in
pacemaker, so all nodes have the same pacemaker config for haproxy and it keeps
haproxy running on all nodes all of the time.
>>
>>
>>
>
>
>
