[FreeNX-kNX] Load balancing with FreeNX

Fri Jun 22 17:22:10 UTC 2007

Prakash Velayutham wrote:
> Hi,
>
> I have the sessions in a shared NFS area now (just the db part and not
> the home), but I still see issues with the load-balancing. Could you
> please explain a little more about your setup? Here is mine.
>
> frontier (load-balancer)
> headnode (NXserver1)
> cellulose (NXserver2)
> protein (NFS server)
>
> All systems running OpenSUSE - 10.2 with NX-1.5.0-73 and FreeNX 0.6. I
> have copied the /var/lib/nxserver/db folder from one of the machines
> upto the NFS server and set the uid, gid as required.
> I have mounted this shared folder in all the systems under
> /var/lib/nxserver/db. Only nx user or anyone from root group is able to
> write to this folder now.
>
> I have set up round-robin load-balancing algo in frontier. I have added
> the 2 load-balanced NX servers in frontier's node.conf like this.
>
> SERVER_LOADBALANCING="Yes"
> LOAD_BALANCE_SERVERS="headnode.chmccorp.cchmc.org cellulose.cchmc.org"
> LOAD_BALANCE_ALGORITHM="round-robin"
>
> I will set it to "load" once I get this simple setup working.
>
> Now if I start a client session to connect to frontier, I can see that
> the sessions gets started in cellulose transparently. I can also see
> that the corresponding files get created in the shared NFS area.
>
> protein:~ # ls -al /home/var/lib/nxserver/db
> total 24
> drwxr-xr-x  5 vdr  root 4096 Jun 22 10:06 .
> drwxr-xr-x  3 root root 4096 Jun 22 10:00 ..
> drwx------  2 vdr  root 4096 Jun 22 10:00 closed
> drwx------  2 vdr  root 4096 Jun 22 10:00 failed
> -rw-r--r--  1 vdr  1051    2 Jun 22 10:06 round-robin
> -rw-------  2 vdr  1051    0 Jun 22 10:06 round-robin.lock
> -rw-------  2 vdr  1051    0 Jun 22 10:06 round-robin.lock.mFTX14846
> drwx------  2 vdr  root 4096 Jun 22 10:08 running
>
> But if I start another session from the same client (a Mac OS X client),
> and try to connect to frontier again, even though the first session is
> still running, it says "Trying to resume session" and actually kills the
> first session and then fails in resuming too.
>
> That is a major issue. Any ideas?
>
> Thanks,
> Prakash
>
>   
>>>> mallah at tradeindia.com 06/21/07 4:02 PM >>>
>>>>         
>
>   
>> Hi Mallah,
>>
>> Could you please explain a little bit more about the shared session
>> storage and how you have it setup? I saw a document saying either we
>>     
Hi,

I am really occupied with some major product roll out.
I hope u someone helps you in this list. I will surely check
ur problem in details when i have some breathing space.

Regds
mallah.

> can
>   
>> setup forwarding on all the FreeNX backend servers to forward all the
>> requests to the frontend load-balance server or setup shared sessions.
>>     
> I
>   
>> tried doing "forwarding" from the slave servers to the frontend
>>     
> server,
>   
>> but did not see any difference.
>>   
>>     
> My personal experience was that the documentation of setting
> up load balancing is not up to the mark for someone doing it
> for the first time.
>
> I do not have in depth knowledge abt the FreeNX . fortunately
> nxserver of FreeNX itself is a shell script so reading it does
> provide help in debugging / understanding.
>
> nxserver use the folder /var/lib/nxserver/db for storing session
> status and information. for session persistence an use should be
> connected to same server where his (suspended) session exists.
> for this the session storage space should be available to the
> load balancer as well as the participating servers. we achieved
> it here via NFS (note this is not the best way , some one used a
> RDBMS for that !!). However if u do not need session persistence
> forget abt this shared stuff to start with.
>
> I find the comments in node.conf confusing , i dumped it and read
> the code of nxserver instead , it was more helpful *as far as load
> balancing is concerned*
>
> i have not done round-robin , i did "load" method that required
> setting up of password less communication between the load
> balancer and rest of servers. it was required so that scripts
> can be run on the rest of servers for probing their "fitness"
> (weight) for serving the client.
>
> overall this process is interesting and challenging
> i regret that due to short of time i cannot give exact answer
> of ur question at the moment all i can say is that ITS DOABLE.
> and IT WORKS. all the best
>
> regds
> mallah.
>
>
>
>
>
>
>
>
>
>
>
>   
>> Thanks,
>> Prakash
>>
>>   
>>     
>
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