[FreeNX-kNX] FreeNX and LVS (Linux virtual Server - cluster)

[Fabian Franz]

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Am Dienstag, 12. Juli 2005 14:31 schrieb Daniel Schwager:

> Fabian, i will have a closer look to your new nxversion. Question: Why so
> you implement the loadbalance+clustering for your own ? 

Because we can't use any other loadbalancer, as we have _persistent_ sessions 
that need to be resumed. Even Microsoft does have a "session directory" in 
Windows Server 2003.

The NX structure was made to be loadbalanced from day 0.

You have a nxserver centrally managing all sessions and you have nxnode 
running as user (possibly on another machine).

nxnode (fabian) -----------------  nxserver ------------------- nxnode (kurt)
                                                  |
                                                  |
                                            nxnode (daniel)

All port forwardings (sound, samba, cups, ...) are transparently managed by 
the NX Proxies running on the acutal load balanced machines.

Note: Load Balancing does only work with SSH encryption enabled at the 
moment ...

> I asked
> because there are projects like LVS having the main-focus on this topics
> and and integration would be (maybe ;-) easier.

Its not necessarily easier.

You have _one_ function in nserver called *_loadbalance() and there you can 
implement whatever algorithm is suitable at the moment.

(Default at the moment is: Round-Robin-Random (Pick one on random))

You could also for example establish a permanent TCP connection to the LVS 
server, to find out to connect to which host.

You could ask a central daemon which server has the lowest load, the least 
running sessions and so on ...

You have unlimited possibilites, but NX itself is loadbalancable, which makes 
it easy to implement, once you've got _one_ server managing the 
loadbalancing. (Same as with LVS).

And you can use the same methods as with LVS to set up a backup server, which 
can take over the sessions once the first server fails. (Not completely 
transparent though)

I hope this answers your questions?

cu

Fabian
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