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Re: [lvs-users] LVS-DR Cluster Some Real Servers Stuck in SYN_RECV

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] LVS-DR Cluster Some Real Servers Stuck in SYN_RECV
From: Malcolm Turnbull <malcolm@xxxxxxxxxxxxxxxx>
Date: Fri, 28 Feb 2014 20:23:06 +0000
Bruce,

You definitely only need one, and personally I find the iptables method easiest.
NB. Your apache instance must be configured to respond to the VIP as
well as the RIP (heath checks are on the RIP)
If you use a local web browser on the real server does it work when
you connect to the VIP ? i.e.

links x.x.x.x

IF so then great but your routing is probably messed up by the lo:0 adapter.






On 28 February 2014 20:01, Bruce Rudolph <brudolph@xxxxxxxxxxx> wrote:
> I followed instructions from two sources
>
>       1)
> http://www.centos.org/docs/5/html/Virtual_Server_Administration/s2-lvs-direct-iptables-VSA.html
>
>                 I updated iptables using the commands on this page.
>
>       2)
> http://ptylr.com/2013/05/01/configuring-lvs-piranha-on-centos-for-direct-routing/
>
>                 This page had information on configuring lo:0 which was
> the final step that I needed to get LVS-DR to work.
>
> The setup this way had been working since last August. It is still
> working on one of the real servers but not on four other ones. Very odd.
>
>
>
> On 2/28/14 2:26 PM, Malcolm Turnbull wrote:
>> snip --  "I have setup
>> LVS-DR using IPTables."
>>
>> Then why are you using a loopback adapter as well?
>>
>> You only need to use one method iptables REDIRECT .... or ...
>> loopbackadapter + arptables settings
>>
>> SYN_RECV means the real server is not replying when hit with a packet
>> that says Hi are you the VIP?
>>
>>
>>
>> On 28 February 2014 19:21, Bruce Rudolph <brudolph@xxxxxxxxxxx> wrote:
>>> I have an LVS-DR cluster which has been running for seven months without
>>> a hitch. Recently, the cluster started to timeout on the majority of
>>> connections. Some connections were passed through to a real server and
>>> processed. I have tried for a week to figure out what happened. What I
>>> found was that one real server out of five is connecting and servicing
>>> the client request. The other four real servers have the HTTP connection
>>> stuck in the SYN_RECV state until it times out (60 seconds).
>>>
>>> In summary, I have seven CentOS 6.4 servers (kernel
>>> 2.6.32-358.18.1.el6.x86_64). Two servers are configured as load
>>> balancers (a primary and a backup) and five real servers. I have setup
>>> LVS-DR using IPTables. The servers have a public IP bound to a NIC
>>> device and an internal VLAN bound to a second NIC. The VIP is configured
>>> on the real servers local loopback (lo:0)  device. The
>>> /etc/sysconfig/ha/lvs.cf was setup properly and everything was running
>>> successfully for seven months.
>>>
>>> We installed new versions of our software for the web service we are
>>> running. Nothing network related. All five real servers were updated the
>>> same way. I am comparing the one working real server from the four that
>>> are not working. So far I have found nothing.
>>>
>>> Any ideas on trouble shooting points?
>>>
>>> --
>>> Best Regards,
>>> Bruce
>>>
>>>
>>> _______________________________________________
>>> Please read the documentation before posting - it's available at:
>>> http://www.linuxvirtualserver.org/
>>>
>>> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
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>>
>>
>
> _______________________________________________
> 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



-- 
Regards,

Malcolm Turnbull.

Loadbalancer.org Ltd.
Phone: +44 (0)870 443 8779
http://www.loadbalancer.org/

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