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Re: [lvs-users] Persistent connections not persisting after failover

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Persistent connections not persisting after failover
From: Joseph Mack NA3T <jmack@xxxxxxxx>
Date: Tue, 19 Aug 2008 10:56:18 -0700 (PDT)
On Tue, 19 Aug 2008, Nicholas Guarracino wrote:

> I have a cluster set up for load balancing a web based application
> that requires persistent connections. I'm using the ipvs sync daemon
> to keep the connection state information consistent between director
> and backup director. However, many times after a failover, the
> persistence does not work and clients end up connected to a different
> realserver. I'm running this on kernel 2.6.18 (RHEL 5, so not exactly
> bleeding edge.)

thanks for the nice description

.
.

> So after the failover, the clients' connections have been reversed:
> 159.63.77.30 is now connected to 10.204.54.166
> 159.63.77.44 is now connected to 10.204.54.167
>
> If I run ipvsadm -L on the backup director before the failover, I do
> see the proper connections so I know the multicast is getting through.

is there persistence on the backup director?

> Any thoughts on what I might be doing wrong?

Possibly nothing. It may be a bug. persistence has a lot of 
problems. I personally suggest using the -SH scheduler for 
your type of setup, but it hasn't been extensively tested 
under the synch demon, so I don't know what will happen 
there. There has been updates (not much) to the synch demon 
since your kernel (and I don't know if they address your 
problem). I can put the ball back in your court by asking 
you to try a recent kernel. I remember something about 
persistence and the synchd recently, but I looked back in my 
list of open problems and didn't see it, so I don't know 
what it might have been.

Horms,
        do you know any problems with the synchd not 
transfering persistent state info to the backup director on 
switch-over?

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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