Microsoft White Paper: 64-bit Terminal Services Scaling and Performance

Microsoft just released a white paper that details their lab test results for scalability testing of Terminal Server running on 64-bit Windows Server 2003.

Microsoft just released a white paper that details their lab test results for scalability testing of Terminal Server running on 64-bit Windows Server 2003. The authors of the paper did lab testing using 32- and 64-bit Windows on three different servers:

  • 2 CPU, 16GB RAM
  • 4 CPU, 32GB RAM
  • 4 dual-core CPU, 32GB RAM

The paper is fairly short and easy to read, but here are the highlights in case you don't have time:

  • As most of you know, the architecture of Windows means that 32-bit Terminal Server cannot scale to more than about 250-300 users per server, regardless of how much hardware you throw at it. Today's 64-bit Terminal Servers can hold at least 600 users, and more are possible as hardware speed increases.
  • Running 32-bit applications on 64-bit Terminal Server will still scale very large, although you'll require about 1.5 to 2x the memory as compared to 32-bit apps on a 32-bit server. (However, these particular lab tests did not come anywhere near exhausting the memory, which means the virtual memory manager did not work to trim applications' working sets. This means that in the real world, the extra memory requirements may not impact performance. More testing will be needed.)
  • The "default" component holding back performance of 64-bit servers with high user loads is disk throughput. With hundreds of sessions on a single server, you can't just use the two internal SCSI drives that ship with the server. You need to think about external arrays or SANs.
  • Once you get the storage performance issues worked out, the ultimate limiting factor is CPU speed. (This means that dual core is a good investment, as the dual core system could support about 60% more users than the single core systems with 64-bit Windows.) This suggests that we should see more users per server as CPU power increases over the next few years.

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Of course this is great in theory, no serious hardware limits anymore.
But in practice I prefer to scale horizontally,
maybe upto 40-50 users per server.
Which company can afford it when a Terminal Server where 500 users are
working on fails ? Maybe an incidental blue screen is survivable,
but a hardware failure would probably take some hours to repair..

This is probably good news for companies that have tens of thousands of TS users
and can afford to have T+1 of those high-end servers.
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I would disagree, typically TS boxes are memory constrained, you run out of memory before anything else. with 64-bit you can now put in more memory (if the server allows like most newer servers do) and get more users on even if it's a 2 way box and the bottleneck becomes the processors. Which in turn still gives you horizontal scaling but you don't need as many boxes.
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Not to mention there is really no cost difference.  Most server hardware today includes 64-bit extensions and the OS cost is the same.  What do you have to lose, except for the "old way of thinking"?
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Guest, no one is suggesting that you not scale-out and have redundancy, they're just remarking that you will be able to fit more sessions on each node.
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We benchmarked  x64 TS in our lab a couple of weeks ago, here is the result.
 
Dell PE2850 Dual 3.2 Ghz, 6 GB RAM
Scripted citrix heavy user (each users running word, escel, project, PI process book...)
 
 
Results:
 
In Windows 2003 server Enterprise edition 32Bits, we can load the server with 70 users without any performance problem (non major paging operation, 23% cpu, low disk activity, 1.4 GB available byte). Same server in x64 with 70 users run out of memory with more that 50% CPU, probably caused by the high paging activity. The out of memory issue was because each process take 50% more space for working set and 1.5-2 X the virtual byte space.
 
 
On a 2 way box like pe2850, if you want to put more that 8GB of memory, that will be cheaper to by another server. Just for this reason, x64 will not be usable for us. I'm a little bit disapointed that citrix release x64 by annoncing that you will be able to put 3 x more users....but not on the same box.. you will need 6 x the memory!
 
All the benchmark released by MS ran on server with 16GB and more RAM. I also read MS article explaining that the only reason to go to x64 is if you reach kernel memory limits of x86. For my servers, Windows 2003 32 bits will be enough because of the 540 MB of paged pool memory now available (instead of 335 on W2K, also the registry is not stored in the paged pool area anymore), 200k pte instead of 100k and better memory management that w2k.
 
We did another benmark with windows 2003 enterprise x86 on a PE2850 Dual 2.8 Ghz dual core, 8 GB ram and we can load 130-150 heavy users without any CPU or memory issue (Many PTE free, Less that 200 MB of paged pool memory used). I think for real life, it's a better way to explore that the x64.
 
Jocelyn Tremblay
 
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I think it will be exiting to see production results, i have no doubt that X64 is gonna benefit the TS side of things, and as others have said, it is just a new option to solve issues. Nothing comes for free so ofcourse you have to pay somewhere.. and in this case that will be on memory when using 32bit applications, the people and companies who takes this in, will have to compare cost and effect in this as well as anything else..
 
Just a new tool for the toolbox to solve the worlds TS-environment problems in my oppinion.
 
/Rene
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I was always under the impression that we wouldn't see a scaling increase on 64bit windows with 32bit apps as wow32.exe would still impose the same memory restrictions as 32bit windows so that apps didn't break? Using a combination of 64bit and 32bit apps obviously would get around this issue....

I am pretty sure that I got that information from a contact at MS... I would have to have a dig through my emails though..

Anyone know anything more about this?

Berny


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Same opinion here.

Let me get this straight. I hope i'd understand the conclusion on this white paper and my own is right.

x64 does have it's advantages for high end servers but when it comes to the common 2 x 3,X GhZ CPU, 4GB RAM Servers it wouldn't improve the TS that much? On the contrary, x64 would use more RAM.
So why should i use x64 for small business environments where i used to deploy servers for 40 - 50 users? Now i have to worry about RAM usage when i would deploy x64 TS on this boxes?
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You're correct, TS will only scale better on x64 if you have more resources, i.e. comparing two systems with 2 CPUs, 4GB of RAM where RAM is the bottleneck, x64 isn't going to help unless you had more RAM.  The advantage of x64 is that there is no 2GB kernel memory boundary, so if you're using a x64 server & OS that supports more than 4GB you'll be able to add more sessions, if the CPUs are not saturated.
 
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Wow32 will impose the same memory limitation on 32-bit applications. (i.e. each 32-bit app will only see a 2GB memory area.) However, the kernel of a 64-bit system has 128GB instead of only 2GB, and that applies regardless of whether you're running 32- or 64-bit apps.

Brian
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I have to agree with Guest, hardware failures, whilst rare, would cause all 600 users to loose their work.  This is not a good thing for most medium sized companies. I usually recommend 30-40 users per box.
 
 
 
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Here's my situation.  We need to install a vendor application that's memory intensive.  A max of 15 conc. users are planned, but the vendor insists they will need 1 GB each in memory.  The vendor also suggests a TS/Citrix architecture since the app interacts with a database (and its users aren't on the same network).
 
I'm trying to figure out how to dice it. The app itself wouldn't need to use 64 bit, but I'm wondering if running TS/Citrix on W2003Enterprise64 will allow me to make better use of a 8GB or 16 GB box, ie allow me to run more sessions. (than W-32bit)
 
Can a 32bit OS even use 16GB of memory?
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We have just deployed 64Bit MetaFrame Presentation Server 4.0 on 2 win2K3 64Bit, DELL 2850 Dual core 3.2GHz, 8G RAM servers, with a EMC SAN backend. What a let down on the Citrix / terminal server performance side. RAM requirements of Office 2003 apps are outragous - Word consumes 125MB to open a 10 page document?? Are you kidding??
 
No 64Bit printer drivers are available from 99% of printer vendors, least of all HP, (and 32 Bit printer drivers won't run on 64Bit Win2K3). Citrix has released only 3 hotfixes for MPS 4.0-64Bit, none of which address printing issues, although their universal print driver works flawlessly.
 
6GB of RAM per server used by 35 users running Office apps, and server performance is so so.
 
My suggestion is to spend your money on 32Bit hardware, OS and Citrix. You'll get much better bang for the buck with a 32bit environment, and you won't have the frustration of trying to find compatible software.
 
Personally I don't feel that software vendors are ready for VARs to be deploying 64Bit environments yet. I won't be installing 64bit for my customers until next year, at which point maybe vendors will have SP1 available for their 64bit apps.
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That may be true, but I've heard another user who tripled his number of sessions  on the same hardware by going to X64.  The difference in his configuration was that he used 8 x 2GB RAM sitcks, for a total of 16GB RAM, which allowed him to scale up to >= 150 concurrent sessions, for a cost of about $1500 for the extra RAM.

If you read the documentation you'll see that 8GB of RAM is just about the break-even point, and you won't be able to scale up w/o going to 12 or 16GB RAM.

http://www.sessioncomputing.com/scaling.htm
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I could not disagree more. We finished implementing a 64 bit Citrix farm to a client a few months back.  They run 4 x HP DL385G4's (Opteron CPU's) with 8GB of RAM each.  We are running 130 users per box.  The app's are typical - Office 2k3 service packed and several inhouse/legacy app's.  Performance is exceptional, Word takes no where near that amount of memory for a 10 page doc (you sure it isn't a Word doc with 10 pages of embedded pictures?!!!) 
 
Printer support for 64 bit seemed slim searching vendors sites - but after phoning them most (Brother, Xerox, HP) emailed us a URL to a generic 64 bit printer driver.  Not all features for all printers available but most work exceptionally well.  I would suggest a separate 64 bit Windows print server though.
 
In all reality I think your problem is the DELL boxes...
 
 
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I would feel that 64 bit is quite a waste of money and effort as :
*based on Dell 1950/2950 Servers
1) The cost of RAM per piece rockets once it goes above 1GB per slot.
The price of 8GB (8x1GB) vs 16GB (8x2GB) could easily cost you another box altogether
2) The overheads of 32bit apps on 64 bit O/S are exponentional especially when it comes to like simple opening of a large document such as Word Document, Presentations with photographs etc, that cause the need for RAM.
3) The overheads per user for the following are not optimised or reduced significantly between 32bit & 64 bit, such as HDD, network and NLB usage.
 
I feel that 64Bit is useful when it comes to cost control when Microsoft Enterprise Edition is being used, for SDS. This allows boxes to be fully pumped with the optimised amount of RAM that the 32bit O/S cannot handle and therefore reducing the number of boxes and the Miscosoft Server Licenses required.
 
On the other hand, there are 3rd party devices/solutions to avoid the need of using the costly MS W2K3 Enterprise Edition just for the SDS.
 
However, in pratical usage, my terminal Server farm running on Dell 1950 with 2x DC Xeon, 8GB RAM, W2K3r2 32bit Ent Edt servers can hold a max of 40 users before some of them complaining that their "systems" are slowing down. I feel that the major bottlenecks are still HDD usage (internal read/write) and Network (10/100/1000mbps but opening/saving 20x20mb-50mb + 40x2-3mb files at once for 40 users).
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ORIGINAL: Guest

I could not disagree more. We finished implementing a 64 bit Citrix farm to a client a few months back.  They run 4 x HP DL385G4's (Opteron CPU's) with 8GB of RAM each.  We are running 130 users per box.  The app's are typical - Office 2k3 service packed and several inhouse/legacy app's.  Performance is exceptional, Word takes no where near that amount of memory for a 10 page doc (you sure it isn't a Word doc with 10 pages of embedded pictures?!!!) 
In all reality I think your problem is the DELL boxes...

 
1st......
On testing secenarios, we do not take into consideration of user overheads, full user loads and extreme user loads. Can we actually run that many users ? The actual load differs from company to company.
At least 50 of my 300 users are using 2 screens and all are on 19" LCD screens. Each of my servers (2xDC Xeon with 8GB RAM on W2K3 ent edt) max out at 45 users + 5 extreme users.
 
User Overheads include MS apps like MS Office, System Antivirus, System Adware or Spyware Blocker (I disable mine but set to scan daily at night), Wallpapers (I set all users to black only), Java JVM, Files on Desktop (I read that more files create overhead as they are considered "open files" and scanned by Antivirus), Shortcuts on Desktop and screensavers.
 
User Loads - User opening at least 2 Windows Explorer, 5 IE Windows, at least 3 email windows (more IE windows if you are using Inotes), company Intranet, Company Internal ERP software GUI (if you are lucky), 2 MS Word documents (5-10MB each due to pictures), 3 MS Excel files (about 1MB each) and 1 PDF file (3MB each).
 
Extreme User Loads - User opening at least 4 Windows Explorer (including shortcuts to shared folders on fileservers), 7 IE Windows, at least 5 email windows (more IE windows if you are using Inotes), company Intranet, Company Internal ERP software GUI (if you are lucky), 3 MS Word documents (2x 5-10MB each due to pictures +  1x20MB file), 3 MS Excel files (2x about 1MB each + 1x10MB) and 1 PDF file (1x3MB each) and a Powerpoint file (1x30MB each) .
 
2nd....
I do not think Brands/Makes of Servers have a part to play in the performance. IMOH, perhaps it is more of what is in the box.
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When we first got Citrix we had 5 windows 2000 servers  (32bit) that had 4 processors/6gig of mem/internal scsi 10k drives all running on Metaframe XP FR3 SP3 Farm. On each server if the user count went past 50 then that server would start to choke. Out of memory pretty much.

Now I do not need all that hardware with 64 bit. Now I have 3 64 bit Citrix 4.0 64 bit servers that are 2dual core processors/8gig of mem/interal 15k scsi drives and I can fit an easy 100 users on each box and not hicup. 64 bit computing has cut down maint costs/hardwarecost/config time cost in half in fact if not more. 64 is the way to go!

Raj

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