Hi all:

I made an application using Qt and want to deploy it on a server to be offered as software as a service. The server is small, it only has 1024 ram and 160 G of disk space. Nevertheless, I'm just testing the idea and if I find people interested I could put more hardware into it.

I've been playing with the server, and after a few ideas given by users in the server forum I installed KVM and VirtualBox to compare and test the idea.

The server is runing ubuntu 9.10, the application is written in C++ using Qt, and basically plots some data, the user makes some picks on the data, and then some operations are carried on upon the data.

The thing is that over the internet X becomes soooo sloooowe that the application becomes useless. I mean, more than a minute for a marker to be shown on a plot... and the user needs to make hundreds of picks.

Is this normal? is virtualization used mostly for non GUI applications when used through internet? or did I just missed something?

KVM just didn't work. I was able to install the machine, but not the X server.

VirtualBox worked much better, but was just soooo slow.

Ah! forgot to add, the user connects to the server using ssh with X tunneling.

ANY ideas are welcome!

best regards.

Do you have enough fast Internet and good processors (ssh needs some power)? Maybe try some VNC. They can degrade bit depth and resolution, so less data needs to be transfered. I was testing connections by it and it has only about one second delayed (without encryption).

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thanks.

I've been reading about VNC, but still don't get the whole thing.

I've been thinking about setting up a "jail" for each user, so that they can only see their home directory, use ssh, and something to let microsoft users to handle the X server like Xming. But as far as I understand this is the same as VNC?

what's the difference between using VNC and Exceed or Xming in terms of performance?

Using linux, I can just connect to the server using ssh and run the application because I have an X server already runing. But this is not so for microsoft users. The advantage of using virtualization was -or so I think- that each user would had it's "little universe", the would connect to ther own virtual machine. But if the performance is so bad when using GUI applications, I'll have to drop it, for now at least.

I would say same as above, VNC is the way to go. I have created CentOS Virtual machines at about 256MB of RAM and been able to use xvnc/vncserver on them perfectly. I would suggest a server just shouldn't have x... it's a waste of resources in the long run and having graphics on a server is unnecessary as servers should be kept light. I would suggest the benefits of SSH tunnels mixed in with vncserver for the best possible security as the biggest problem with VNC tends to be people running it unencrypted what is as weak security wise as straight FTP. Past this VNC I find doesn't gave any real performance hits at all... maybe if something graphically intense was run you might see something but generally most things I use over VNC are not that intense at all.

I have heard tightVNC will handle SSH tunnels on the users behalf but I have not tested this myself.

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