[FreeNX-kNX] nxserver loadbalance.

[Dimitar Paskov]

> Hi all,
>
> I'd like to use a cluster to serve desktops via freeNX.
> I haven't seen much on the net about it.
>
> My initial idea was to do something like use a gateway to divide the
> sessions between servers with NAT or something along the lines of LVS.
> But reading in the list I see that Fabian recommends the nxserver
> loadbalance mecanisms.
> http://mail.kde.org/pipermail/freenx-knx/2005-July/001546.html
>
> Then looking for more info on how to do it, I read this
> http://www.nomachine.com/ar/view.php?ar_id=AR10B00070
> that suggests it isn't yet possible.
>
> Can someone point out the facts to me?
>
> Thanks.
> Chris.

Yes, there are many ways to accomplish load balancing between nxserver(s) and 
nodes. For example the simplest is to use the built in functions in freenx 
for load balancing and you will have a central nxserver which balances 
connections and sessions between many nodes. But be ware that in this setup 
every connection that you have <client-nxserver-nxnode> will go through this 
load balancer nxserver (check usage of netcat command in nxserver). That 
means if this server fails for some reason (hard disk crash, network 
problems) everything will fail - sessions will crash, session info lost, no 
connection between nodes and clients, etc. Thus this is only for load 
balancing but not for high availability. If you want to make a good cluster 
then you need at least:
- a central storage for session information (nfs, mysql, etc.)
- 2 or more nxservers or a little more intelligent nxclient with built load 
balance algorithm and nxserver working on every node

We have mange to make this kind of solution for our company and it has mysql 
storage for session info, load balance algorithm built in nxclient, and 
nxserver on every nxnode. Upon connection nxclient checks which is the least 
loaded server and connects directly to nxserver on it so when trying to 
resume session later it will connect you to the one that has your session.

Another solution is to use openMosix but I haven't try it so I'm not sure how 
to do it.

If you are interested I can give you more detail of the whole setup.