Unless you are running on a UNIX platform, the most obvious difference to
me is that VNC does not offer the option to have multiple concurrent users
make use of a single server.
Here are some other advantages of Citrix over VNC:
- Multi-user: You can have many users use the same machine at the same time
- Automatic Local Drive, Printer, Sound, Clipboard, Serial port mapping.
You get access to all of these remote peripherals from within your remote
session. (yes, I know VNC has limited clipboard sharing). File copying is
as simple as drag and drop from the server or network drive to your local
drive and back. I have even heard of some people who are hotsynching their
PDA's though the MetaFrame session.
- When you need to upgrade software, you need only upgrade your Citrix
servers instead of a whole bunch of workstations. Recent versions of Citrix
MetaFrame even allow you to have the client automatically upgraded on
remote PC's.
- Seamless sessions: Citrix MetaFrame allows you to run applications in
their own window, as if they were really running right on your desktop.
Even your whole desktop theme gets applied to the application's window like
colours and fonts. You can minimize, and resize windows. It is really well
integrated. You can even put shortcuts right on the remote users desktop.
- Reliable sessions: Sessions are much more responsive than VNC sessions,
even over low bandwidth (like 28.8 dial-up modem or less), due to the way
the technology has been implemented. You will virtually never see screen
update failures with the ICA client.
- Can be load balanced and clustered: If you have several servers, and one
server goes down or is very busy, the next user will be connected to a
server that isn't as busy.
- Security: If you use technology like VNC or PC Anywhere, each workstation
requires its own IP address. Assuming that your workstations are behind
firewalls, you will need a port open for each of them. By contrast,
MetaFrame only requires a single port though which everyone connects. Also,
since it is a server, you have ultimate physical control over the machine
and can afford to put your money into better quality hardware and support
things like RAID or redundant power supplies, thereby reducing the chances
of system failure.
Citrix MetaFrame is a great, cost effective tool if you are running a
standardized environment. Depending on the configuration of the server and
the applications being used, each server can host up to 100 concurrent
users. There isn't actually a fixed number. Its more a matter of how much
horsepower you give it (memory, CPUs, bandwidth, etc). Sure it will cost
you more initially, but in the long run, your maintenance costs will be way
down when compared with an army of workstations dedicated to remote access.
On the other hand, if everyone will be running their own experiments in
their remote sessions, and virtually no two users will be using the same
application, you would probably do better to have them connect to their own
workstation and let them mess that up. At least when their machine goes
down, it won't take everyone else with them. Although NT technology
prevents one application from crashing another, there is nothing that
really prevents one application from consuming virtually 100% of the CPU so
as long as your applications are well behaved, you won't have a problem.
There is (or at least was) a less expensive solution. Citrix may still
offer a product called WinFrame. Basically it is based on the Windows 3.51
platform. Although it doesn't support the latest GUI and hence the latest
applications, it could suit your needs depending on your requirements. The
biggest advantage to WinFrame over other solutions such as Windows Terminal
Services or even Citrix MetaFrame is the licensing. It is a very simple
concurrent licensing scheme. If you want to support 1000 users, but never
expect to have more than 40 users at any given time, you need only worry
about getting 40 licenses. There are no CALS or any other licenses
required. Its a great way to make a custom application available to the
world for example. Contact Citrix if you don't see it on their web site.
If you only have a few users who would be using such a service, you might
want to give Windows XP Pro and it's "Remote Desktop Connection" a try. It
is basically a one user version of Windows Terminal Services and includes
many of the features available in MetaFrame. Remember, one user at a time,
whether they are local or remote.
Expensive is all relative. Any good IT architect will look beyond the
initial setup cost and weigh at the long term costs like maintenance and
support as well as the benefits the technology brings to the organization
such as gains in productivity and flexibility.
Sure VNC seems like a nice inexpensive technology to implement up front...
for small groups of users. As soon as the number of users increases though,
so do your support costs.
Don't get me wrong, I use VNC and firmly believe that VNC does have its
place. It's just not for remote access by more than a few users a corporate
environment. On the other hand, software like Terminal Server or MetaFrame
are not the right kind of tools to use for supporting users or servers.
In the long run, you will find that you can cut your costs and increase
user satisfaction by using the right technology in the first place. Isn't
that what IT is all about?
Michael Milette
At 10:41 AM 2002-04-11, you wrote:
>A major figure in our Medical School (Sr. Vice President for Health
>Sciences) sent the memo below to all of our faculty this morning. The
>gist of the memo is that Citrix was considered for use by physicians in
>the Med School but it was found to be too expensive. I'm wondering if VNC
>could do the job. Does Citrix do the same thing as VNC or is it entirely
>different?
>
>Mike
>
>--
>Michael B. Miller, Ph.D.
>Assistant Professor
>Division of Epidemiology
>University of Minnesota
>http://taxa.epi.umn.edu/~mbmiller/
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