[lvs-users] Cluster using only one of two available nodes

To: "lvs-users@xxxxxxxxxxxxxxxxxxxxxx" <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: [lvs-users] Cluster using only one of two available nodes
From: "Ross Michael (LEEDS PCT)" <michael.ross@xxxxxxx>
Date: Tue, 26 Jul 2011 09:13:30 +0100
Hi all,

I have something of a bit of an odd issue that I have so far been unable to 
find a solution for, so I am hoping that you can help.

I have a 4 server rig:
2 x directors (heartbeat HA),
2 x apache servers                 ,
Virtual IP                                    

The HA directors are set up and appear to be working perfectly (and failing 
over correctly).  The Apache servers are also working as expected and will both 
happily return content when connected to directly by IP.  However, when 
connecting through the virtual IP, the currently active director will only send 
requests to one of the servers and seems to completely ignore the other one.

What makes this rather odd is that the director recognises both apache servers, 
checks them regularly for response and reports correctly if either one goes 

ipvsadm -Ln
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP rr persistent 600
  ->             Route   1      0          0
  ->             Route   1      0          0

You can see both servers.  Both are responding to the director alive requests:
Both apache logs report: - - [26/Jul/2011:09:02:30 +0100] "GET 
/alive.html HTTP/1.1" 200 12 "-" "libwww-perl/5.805"

The director is set up like this:-

        real= gate
        real= gate
        fallback= gate
        receive="Still alive"

If I take out 8.121 (the apache server it insists on using), it will not direct 
traffic to 8.122.  Something else I have noticed is that if no apache server is 
available, it will not use the fallback either.

Something else I have noticed, but i am not sure it is relevant is that if I do 
a ipvsadm -Ln -stats, I get:

IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port               Conns   InPkts  OutPkts  InBytes OutBytes
  -> RemoteAddress:Port
TCP                  358     7618        0   527015        0
  ->                    0        0        0        0        0
  ->                    0        0        0        0        0

Notice that all the connections are on the virtual IP and the real IP's are 
saying zero across the board even though the system appears (on the surface) to 
be working properly.  I thought that for every connection via the VIP, it would 
increment 'Conns, InPkts etc' for the real server, though I could be wrong.

Any thoughts would be most appreciated.




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