[CentOS-virt] WinXP Xen guest: compare VNC vs RDP

Manuel Wolfshant wolfy at nobugconsulting.ro
Wed Apr 22 23:58:09 UTC 2009

On 04/22/2009 10:35 PM, Ed Heron wrote:
>   I'm experimenting with using WinXP Xen guests as an alternative to 
> upgrading workstations.  The administrative advantages seem overwhelming.
>   Please share thoughts about using VNC vs RDP for remote desktop 
> connections.
I had to create 6 windows XP instances for a project a couple of months 
ago. Here are our conclusions, now that the project is over and the VMs 
have been decommissioned:
- XP was MUCH faster in Xen, compared to real hardware (!)
- RDP beats VNC in terms of speed any time, any place. I cannot evaluate 
precisely the factor, but empirically I'd say that in our conditions 
(WAN link, 6 Mbps upstream link on one site shared with other projects,  
100 Mbps on the other site) it was at least 2-3 times faster.
- rdesktop ( the linux app) is really cool, as it allows you to 
share/transfer local resources to the remote XP session (for instance 
you can map a local directory as a remote networked disk, without the 
hassle of passing via Network Neigh.). VNC forces you to either 
explicitly map such resources (hence you would also need something like 
samba on the linux side) or use scp.
- the only problem with RDP is that by default Windows limits the number 
of simultaneous connections. but patches do exist (which violate the 
licensing/usage terms, so beware).

As of implementations issues .. I had two (or should I say three?) problems:
- one is detailed in an older thread on this list ( look for "Using the 
parallel port from domU", 02/02/2009).
- second is due to Xen creating a large file with the same size as the 
disk given to the VM. I would have believed that sparse files would have 
been used, but df showed the opposite. I have seen 20 GB of space 
allocated, despite XP only using less than 5.
- last issue did not occur with stock Xen but with v3.3: Java inside the 
VM went nuts and starting consuming 99% of the processor.. while doing 
nothing. Once we reverted to stock Xen from C5.2, it went back to normal.

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