Are you using x64 Terminal Servers or Citrix? Why or why not?

Coming from a small country like Denmark we dont have that many really large(in US terms) farms. So for most of our customers they would not want to put more than 30-40 users pr. server.
Reasons are simple, if hardware fails, how big is the impact? If you need to rush a change on a server that requires a reboot? how big is the impact?

I can understand the use of 64bit to get 200+ users on the same box when you are in a large scale enterprise with thousand and thousands of users. The overall impact in case of hardware failure is not as great and on top of that these organisations typically need to save anything they can when it comes to Datacenter Space and cooling.

They way i have mainly seen x64 bit used it when it comes to extreme workload application silos. In these cases where it is simply memory intensive workloads some times it is a good solution to go x64 and be able to keep a normal 'user load' on the servers.

All in all i think alot of people are hesitant moving to 64-bit when they are unsure whether they can rely solely on universal printer drivers, and when they fear losing half their organisation in case of hardware failure.

The great results i have seen with Terminal Servers and XenApp virtualized lately makes me sure i would carve up a box like the one you mentioned. Atleast until we get Live User Migration.. and money rains from the sky ;-)

/LamerSmurf

I don't run x64 TS or Citrix mostly due to the applications. Many are not coded for x64 and since application delivery is the name of the game, I stayed on 32 bit.  I have been able to split the load by running more 32 bit OS on in a hypervisor environment.

x64 sounds nice in theory, but it think it missed its window of opportunity with all the hypervisors coming onto market and subsequent competition for market space. Chances are if you can afford x64 operating system, you can afford x32 running on a hypervisor.  

We decided against using x64 verison of windows 2003 becaue there were not enough MUI langauage packs available (we use 30 MUIs for our Citrix desktop environment) and because of difficulty obtaining print drivers from vendors etc.  Also the version of Citrix for x64 was never truly a 64 bit version, just presentation server/Xen app ported to work with the x64 version of the OS.

We are going to investigate the 64 bit version of windows 2008 when Delaware is eventually released.

We run x64.  We use the Citrix UNIVERSAL Printer for printing, and it works like a charm. 

Softgrid can't run under an enterprise class OS provided by its own vendor.  Comedy GOLD! </sarcasm>

Most Citrix customers get bombarded with marketing messages telling them that 64bit is the answer and solves all their datacenter problems - in my experience this is rarely the case.

Main reasons why people generally steer clear of 64bit platforms;

1. Application Performance - 99% of commercially available applicatons are only available as 32bit applications. When running on a 64bit OS these are run in an emulation mode similar to NTVDM when running 16bit apps on a 32 bit platform. This means there's a natural overheaed to your applications, therefore you at best won't see any performance improvement in your apps and worst they may be slower.
2. 16 Bit Applications - if you have any of these, good luck running them on 64bit! Most Larger banks and insurance companies maintain legacy applications, normally some of them will be of the 16bit flavour.
3. Softgrid - No 64 bit client til version 5, so this rules out any softgrid houses!
4. Printing - yes, the UPD will work in 64 bit, but for customers with thin client environments this isn't a viable option normally. This should improve when Citrix finalise the UPD Print Server, but until then you're stuck managing at best multiple versions of printer drivers or at worst having to replace a whole load of printers.
5. Stability - loading a server with 500 users in a 1000 seat environment might seem like a good idea when looking at datacenter footprint and server management costs - right up until the day when Server A blue screens and 50% of your users are out of action.
6. Disk speed - unless you've dumped your annual budget on buying in flash disks for you servers, disk speed is going to be a big bottleneck when loading your servers with 200+ users. When your Write Cache is full terminal services is pretty much dead in the water. You can normally accomodate 150-200 users with Battery Backed write cache add-ons, but even considering multiple array controllers, your going to have a big pain point if you're trying to accomodate 200-500 sessions on a single box!

Virtualisation is far more common with enterprise customers that 64bit platforms in my experience, with the exclusion of Exchange and SQL servers.

Also I can't match up the user load stats that are fed to me by the multiple marketing machines extolling the virtues of 64bit...

Typical real world workloads using MS Office Suite and CRM application based on "Acceptable Performance";

2003 Enterprise R2 x64, XenApp 4.5 x64 R02, 16GB RAM, 2xAMD Dual Core Proc = 120 Users

4x 2003 Standard R2 32bit, XenApp x64 R02, 4GB RAM, 1x vCPU, VMware VI3 Enterprise = 35 Users per server

DISCLAIMER: This is based on real world systems - not a performance testing lab. Interpret it how you wish!

So... If i've done my maths correctly - on my 64bit platform I'm getting 120 users before the performance degrades, across my 4 virtualised instances I'm getting 140 users. 

As soon as software developers begin to develop as standard for 64bit platforms, it brings the 64bit versus 32bit argument into scope, however until then - in my opinion - there's no incentive to transition.

Anyway, thats my two cents!

Whoops - that should have read:

Typical real world workloads using MS Office Suite and CRM application based on "Acceptable Performance";

2003 Enterprise R2 x64, XenApp 4.5 x64 R02, 16GB RAM, 2xAMD Dual Core Proc = 120 Users

4x 2003 Standard R2 32bit, XenApp 4.5 R02, 4GB RAM, 1x vCPU, VMware VI3 Enterprise = 35 Users per server

We have stayed away for now.

We have about 3500 different individual external users(only about 350 concurrent) with every printer under the sun. This has always made it hard to supporting all these different printers. Needless to say getting 64 bit drivers and having 3500 clients install them on all sorts of different hardware and OS versions is not going to happen. But with 4.0 we started using UPD and the universal printer, and think we have things beat. That universal printer is nice.

We are about to start upgrading to 4.5 and will start testing some 64 bit. Hopefully it works. We are a rare case that falls under Microsoft's "external connector License" for terminal server so if we could cram 200+ users on two boxes that would greatly reduce our TS licensing.

 Right now we have 6 servers that our customers hit and we cram about 60 users on each leaving one out for n+1. If I could take that down to 3 servers that could save me 24k on licensing.

Now that said there is always the fear if I go 64 bit and a server takes a dive I just bounced 200 customers as apposed to just 60.

What about 2003 Enterprise R2 x32 bit and 16 GB of RAM?  You should be able to get more than 120 users.

Joe

Truth is TS is a glorified workstation that happens to allow multiple users to connect a single host.  Organizations have yet to consider running their fat clients on x64 versions (there are x64 versions of XP and Vista) so how can we be expected to make that transition on this glorified multiuser workstation (Terminal Server)?

The guest above makes a great point on how many users on a single host is too much?  This is a Microsoft world we are living in.  Not Unix or Mainframe.  One important lesson that Microsoft given us is, "its good enough".  That doesn't translate to security and stabiliy. To be fair, Microsoft has done a lot (and still is) to correct this but their partners have not...  But what good is a stable OS when a flaky application threatens to take down the entire system?

Now take in the fact that Microsoft announce that Windows 2008 will be the last 32-bit OS.  That means at some point in time we will have to solve the x64 problems and migrate... Or dare I say,  VDI!

Joe

Hi Joe, 

I'd say that single server scalability is largely subjective based on the applications, but again in a similar setup with 16GB RAM and 2003 Enterprise 32bit I'd expect to see 100-120 users (ballpark).

Although 32bit Enterprise edition addresses the compatibility aspect, you're still likely to encounter similar scalability issues as when you have a large number of users on a 64bit platform albeit with the added limitation of the 32bit memory management.  

I'd agree there will be cases when you can get more but again i'm basing this on a situation where users are running 3-4 apps of the types in my previous post. It also largely depends on what you would deem to be acceptable performance. 

Andy

Lack of true x64 support by application virtualization tools. I.e. ThinApp doesn't currently capture 64-bit applications, SoftGrid has no x64 support, SVS isn't x64 compatible etc...

Some nice info on Itanium processor restriction of 32-bit processes.
http://msdn.microsoft.com/en-us/library/ms241064.aspx

On 6 x HP Proliant BL480c (8 way blades), 8GB RAM, running Windows 2003 Enterprise 64bit R2.

We used HP x64 Universal Print drivers & Lexmark x64 Universal Print drivers for Session printers and Citrix Universal Print drivers for client mapped printers.

We managed to get 85% of their applications streamed to server using Citrix Application Streaming. Even difficult applications like SAPGui 640 worked fine :) Just have to remember the registry redirection for 32bit applications ;P

If I could do it all over again, I'd definitely suggest 64bit but with Provisioning Server for Datacentres instead!

Rgs Sharin Yeoh (sharin.yeoh@mlogic.com.au)