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

Ed Heron Ed at Heron-ent.com
Thu Apr 23 00:19:54 UTC 2009

From: "Manuel Wolfshant", Wednesday, April 22, 2009 4:58 PM

> ...
> - XP was MUCH faster in Xen, compared to real hardware (!)

  I've been pretty happy with the performance, as well.

> - 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.

  Interesting.  Thanks.

> - 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.

  Either way, I won't be having local resources.  Trying to keep it simple.

> - 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).

  I am interested in the multiple connections allowed with VNC for support 
type console sharing.  When connected with RDP, the console of the VM has a 
login screen, so you can't use VNC to the console at the same time as a RDP 

> 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).

  My printers are all network printers, yay!

> - 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.

  I think I've got the VM's setup with sparse files.  An ls shows the 10GB 
size, but df doesn't show all the space in use.  However, this is a minor 
issue.  The virtual server I'm looking at has the capacity for a couple of 
terabytes of hardware RAID storage.

> - 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.

  I'm going to be trying to avoid using other than stock Xen.  This has got 
to reproducible and supportable.  I'm thinking of setting up a local repo to 
prevent automatic updates from breaking anything.

  Thanks for all of the information.  Makes me wonder what happened to 
eliminate the need...

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