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Re: [lvs-users] Cannot figure out failover balancing

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Cannot figure out failover balancing
From: "Ryan O'Hara" <rohara@xxxxxxxxxx>
Date: Mon, 23 Jan 2012 22:00:40 -0600

On 01/23/2012 03:40 PM, Peter Scott wrote:
> Thanks!  We're going to look at Pacemaker (which does seem to be
> supported on RHEL6 after all).  Looks like what we want.

Pacemaker is not supported in RHEL6. It is considered Tech Preview.

Ryan

> On 1/20/2012 5:43 PM, David Coulson wrote:
>> Why not just setup a resource in rgmanager (I'd say use pacemaker, but
>> RedHat doesn't support that yet), and move the MySQL IP between the
>> hosts, rather than messing around with IPVS?
>>
>> David
>>
>> On 1/20/12 8:13 PM, Peter Scott wrote:
>>> Hello.  We are using the Redhat load balancing add-on that comes on RHEL
>>> 6.  We want to have highly available MySQL; we have two co-master MySQL
>>> servers that replicate to each other.  MySQL says that that updates
>>> should only come in to one of these at a time because of the possibility
>>> that conflicting updates arrive at each server simultaneously.  So we
>>> want to use LVS to direct all traffic to one of the co-masters (call it
>>> mysql01) except when it is down, in which case to direct all traffic to
>>> the other one (call it mysql02).
>>>
>>> We thought this requirement would be common enough to be addressable via
>>> stock LVS capability.  Our initial thought was to set the weight of
>>> mysql01 to 1 and mysql02 to 0.  However, new connections still went to
>>> mysql02.  We discovered
>>> http://archive.linuxvirtualserver.org/html/lvs-users/2008-10/msg00101.html
>>>
>>> and set the /etc/sysctl.conf parameters, also tried setting them via the
>>> equivalent files in /proc/sys/net/ipv4/vs/, still connections went to
>>> both servers even when we waited beyond the persistence timeout of 600s.
>>>
>>> Because of this behavior, we are not able to test whether our approach
>>> is sound to begin with; i.e., if mysql01 goes down will traffic be
>>> redirected to mysql02 even though its weight is 0?  We thought that if
>>> it was the only machine up in its group the weight would not matter.
>>> But would like to know if that assumption was accurate also.
>>>
>>> Here's that section of our lvs.cf:
>>>
>>> virtual MySQL {
>>>         active = 1
>>>         address = 192.168.185.115 eth0:6
>>>         vip_nmask = 255.255.255.0
>>>         fwmark = 3306
>>>         port = 3306
>>>         persistent = 600
>>>         use_regex = 0
>>>         load_monitor = none
>>>         scheduler = wlc
>>>         protocol = tcp
>>>         timeout = 6
>>>         reentry = 15
>>>         quiesce_server = 0
>>>         server MySQL01 {
>>>             address = 192.168.185.51
>>>             active = 1
>>>             port = 3306
>>>             weight = 1
>>>         }
>>>         server MySQL02 {
>>>             address = 192.168.185.52
>>>             active = 1
>>>             port = 3306
>>>             weight = 0
>>>         }
>>> }
>>>
>>> Would appreciate any advice.  Thanks.
>>>
>>> _______________________________________________
>>> Please read the documentation before posting - it's available at:
>>> http://www.linuxvirtualserver.org/
>>>
>>> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
>>> Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
>>> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
> Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users

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