[lvs-users] Unbalanced Real Servers

["Götz Rieger" <goetz.rieger@xxxxxx>]

Hi all,

I've set up a three-node (Apache 2.2/RHEL 5.3) web cluster with an LVS-LB 
(CentOS 5.2) in front and NFS storage in the back. I'm using keepalived on the 
LB. The hardware is identical and everything Apache (content and web server) 
lives on two NFS shares on a fourth node.

I'm doing a load test now using The Grinder with four load test clients. The 
problem I'm facing is an extremely uneven distribution of ActiveConn on the 
real servers:

[root@lvst1 ~]# ipvsadm -L -n                                          
IP Virtual Server version 1.2.1 (size=4096)                            
Prot LocalAddress:Port Scheduler Flags                                 
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn  
TCP  194.xxx.xxx.xxx:80 rr                                              
  -> 192.168.xxx.xxx:80            Masq    1      137        421        
  -> 192.168.xxx.xxx:80            Masq    1      203        509        
  -> 192.168.xxx.xxx:80            Masq    1      0          630

Prot LocalAddress:Port Scheduler Flags     
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  194.xxx.xxx.xxx:80 rr                                            
  -> 192.168.xxx.xxx:80            Masq    1      232        424       
  -> 192.168.xxx.xxx:80            Masq    1      5          418       
  -> 192.168.xxx.xxx:80            Masq    1      3          419
 
The configuration is as easy as it gets:

[root@lvst1 ~]# cat lvs.conf
-A -t vs:http -s rr
-a -t vs:http -r node1:http -m -w 1
-a -t vs:http -r node2:http -m -w 1
-a -t vs:http -r node3:http -m -w 1

So persistence is disabled. The problem is of course the web servers are 
getting very uneven load, one is doing all the work while the others are idling 
around...

I'm now testing with the ll scheduler and now ActiveConn are exactly balanced. 
Is there any reason to not use ll? I've seen Willy's statement about ll not 
being suitable for a web server. 

It might just be me lacking in-depth understanding but I would be grateful if 
somebody could give me a hand. I've already tried to digest all the How-To 
information.


Cheers,
Goetz

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