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Apr 12

Multi-monitor support for Citrix ICA Sessions - dual screens and the like

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Update - I got a note from Stefan Vermeulen at http://www.printingsupport.com regarding some info from Brian Madden’s forum and have posted it in the Comments - this includes the Registry tweak to increase the buffer to 16Mb per session.

I’ve been asked about multi-monitor support for Citrix ICA Sessions twice in the last week or so from two different sources so I thought it useful to pop this in as a post?

Using Multiple Monitors with Seamless Windows

Seamless Windows Problem with NVidia Dual Screen Client

But this should give a very clear idea on what is possible? As you can see Dual Screens is really only the starting point?

Graphical Display Issues with One or More Monitors

A variety of issues surrounding the graphical display on the client device can be a result of memory setting per ICA session.

The maximum memory allowed for use as a buffer by each client connection on a MetaFrame server is 7,680,000 bytes. This maximum is a limit to the operating system and is not configurable. Up to the maximum amount of memory can be set in the Citrix Management Console at the farm or server level, but this also can be application-dependent. When the memory limit is exceeded in a seamless connection, the session is displayed in a fixed window with scroll bars. Seamless mode factors in the entire resolution of all monitors in a multi-monitor configuration. This chart shows various combinations of color and resolutions with various numbers of monitors and the amount of memory required for the ICA session.

Don’t forget that this is a maximum limit "per session" and ICA will always try to utilize "session sharing" where ever possible to limit the number of licences consumed, so if you are trying to run two large display applications in Seamless mode - and they are sharing the session - then you will have to add together the memory required for each application and ensure that it doesn’t exceed the max. 

Number of Monitors Resolution  Color Depth  Memory Required 
1 640 x 480 16 Colors 153,600
2 640 x 480 16 Colors 307,200
4 640 x 480 16 Colors 614,400
8 640 x 480 16 Colors 1,228,800
12 640 x 480 16 Colors 1,843,200
1 800 x 600 16 Colors 240,000
2 800 x 600 16 Colors 480,000
4 800 x 600 16 Colors 960,000
8 800 x 600 16 Colors 1,920,000
12 800 x 600 16 Colors 2,880,000
1 1024 x 768 16 Colors 393,216
2 1024 x 768 16 Colors 786,432
4 1024 x 768 16 Colors 1,572,864
8 1024 x 768 16 Colors 3,145,728
12 1024 x 768 16 Colors 4,718,592
1 1152 x 864 16 Colors 497,664
2 1152 x 864 16 Colors 995,328
4 1152 x 864 16 Colors 1,990,656
8 1152 x 864 16 Colors 3,981,312
12 1152 x 864 16 Colors 5,971,968
1 1280 x 1024 16 Colors 655,360
2 1280 x 1024 16 Colors 1,310,720
4 1280 x 1024 16 Colors 2,621,440
8 1280 x 1024 16 Colors 5,242,880
12 1280 x 1024 16 Colors unsupported
1 1600 x 1200 16 Colors 960,000
2 1600 x 1200 16 Colors 1,920,000
4 1600 x 1200 16 Colors 3,840,000
8 1600 x 1200  16 Colors 7,680,000
12 1600 x 1200 16 Colors unsupported
1 640 x 480 256 colors  307,200
2 640 x 480 256 colors 614,400
4 640 x 480 256 colors 1,228,800
8 640 x 480 256 colors 2,457,600
12 640 x 480 256 colors 3,686,400
1 800 x 600 256 colors  480,000
2 800 x 600 256 colors 960,000
4 800 x 600 256 colors 1,920,000
8 800 x 600 256 colors 3,840,000
12 800 x 600 256 colors 5,760,000
1 1024 x 768 256 colors 786,432
2 1024 x 768 256 colors 1,572,864
4 1024 x 768 256 colors 3,145,728
8 1024 x 768 256 colors 6,291,456
12 1024 x 768 256 colors unsupported
1 1152 x 864 256 colors 995,328
2 1152 x 864 256 colors 1,990,656
4 1152 x 864 256 colors 3,981,312
8 1152 x 864 256 colors unsupported
12 1152 x 864 256 colors unsupported
1 1280 x 1024 256 colors 1,310,720
2 1280 x 1024 256 colors 2,621,440
4 1280 x 1024 256 colors 5,242,880
8 1280 x 1024 256 colors unsupported
12 1280 x 1024 256 colors unsupported
1 1600 x 1200 256 colors 1,920,000
2 1600 x 1200 256 colors 3,840,000
4 1600 x 1200 256 colors 7,680,000
8 1600 x 1200 256 colors unsupported
12 1600 x 1200 256 colors unsupported
1 640 x 480 16 bit color 614,400
2 640 x 480 16 bit color 1,228,800
4 640 x 480 16 bit color 2,457,600
8 640 x 480 16 bit color 4,915,200
12 640 x 480 16 bit color 7,372,800
1 800 x 600 16 bit color 960,000
2 800 x 600 16 bit color 1,920,000
4 800 x 600 16 bit color 3,840,000
8 800 x 600 16 bit color 7,680,000
12 800 x 600 16 bit color unsupported
1 1024 x 768 16 bit color 1,572,864
2 1024 x 768 16 bit color 3,145,728
4 1024 x 768 16 bit color 6,291,456
8 1024 x 768 16 bit color unsupported
12 1024 x 768 16 bit color unsupported
1 1152 x 864 16 bit color 1,990,656
2 1152 x 864 16 bit color 3,981,312
4 1152 x 864 16 bit color unsupported
8 1152 x 864 16 bit color unsupported
12 1152 x 864 16 bit color unsupported
1 1280 x 1024 16 bit color 2,621,440
2 1280 x 1024 16 bit color 5,242,880
4 1280 x 1024 16 bit color unsupported
8 1280 x 1024 16 bit color unsupported
12 1280 x 1024 16 bit color unsupported
1 1600 x 1200 16 bit color 3,840,000
2 1600 x 1200 16 bit color 7,680,000
4 1600 x 1200 16 bit color unsupported
8 1600 x 1200 16 bit color unsupported
12 1600 x 1200 16 bit color unsupported
1 640 x 480 24 bit color 921,600
2 640 x 480 24 bit color 1,843,200
4 640 x 480 24 bit color 3,686,400
8 640 x 480 24 bit color 7,372,800
12 640 x 480 24 bit color unsupported
1 800 x 600 24 bit color 1,440,000
2 800 x 600 24 bit color 2,880,000
4 800 x 600 24 bit color 5,760,000
8 800 x 600 24 bit color unsupported
12 800 x 600 24 bit color unsupported
1 1024 x 768 24 bit color 2,359,296
2 1024 x 768 24 bit color 4,718,592
4 1024 x 768 24 bit color unsupported
8 1024 x 768 24 bit color unsupported
12 1024 x 768 24 bit color unsupported
1 1152 x 864 24 bit color 2,985,984
2 1152 x 864 24 bit color 5,971,968
4 1152 x 864 24 bit color unsupported
8 1152 x 864 24 bit color unsupported
12 1152 x 864 24 bit color unsupported
1 1280 x 1024 24 bit color 3,932,160
2 1280 x 1024 24 bit color unsupported
4 1280 x 1024 24 bit color unsupported
8 1280 x 1024 24 bit color unsupported
12 1280 x 1024 24 bit color unsupported
1 1600 x 1200 24 bit color 5,760,000
2 1600 x 1200 24 bit color unsupported
4 1600 x 1200 24 bit color unsupported
8 1600 x 1200 24 bit color unsupported
12 1600 x 1200 24 bit color unsupported

posted on Wednesday, April 12, 2006 6:18 AM


Feedback

# re: Multi-monitor support for Citrix ICA Sessions - dual screens and the like 4/15/2006 11:30 PM Stefan Vermeulen

Here is a quote from a post from Claudio overruling the 8mb limit on a 2k machine:
http://www.brianmadden.com/forum/tm.aspx?m=12743
Not sure if it’s stull there today and if the total limit is still 16mb.
Remove Comment 75282

# re: Multi-monitor support for Citrix ICA Sessions - dual screens and the like 4/16/2006 5:35 AM Dave Caddick

Thanks Stefan, I’ll post that here as well just in case others find it useful?
Here’s a story from Cláudio he once posted somewhere on how he did so you can use it for your own basis:
I have no idea if it is already fixed on Windows 2003 as none of my monitors can handle such resolutions.
And I have only one monitor so I cannot even try multi-monitor setups.
Although Citrix may allow you to do this, it is still limited on the resolution, color and number of sessions. This means a certain number
(memory allocated to the client) has a maximum value. What means the more resolution you have, you will not be able to have as many sessions as you want in high color for example.
More information:
"Citrix says with there Metaframe for W2k and ‘Feature Release 1′ upgrade, you can support ‘multiple monitors’ and ‘greater colour resolution’. in actuality, the correct word is OR not AND ! Which means it can support 8 screens but only in 2-bit colour mode OR 1 screen at 16 million colours. The reason is due to the amount of memory that Citrix reserves for the video memory for the client.
By default, it is exactly 7680000, which is the maximum value the Citrix utility, "TWConfig", will accept. Now this value is out of 16Mb of total client session memory space. However, running the minimum 3 monitors for the traders at 16-bit requires 7,864,320 bytes, which is 184320 more than the default. So, we asked Citrix why their stuff didn’t work. Finally after almost 2 months of playing email tag, they came back with a Registry entry change.
Here is what they sent us:
Win2k has a session pool limit of 16MB. The ICA pseudo frame buffer comes out of this session pool, and the maximum size of the frame buffer is specified by the registry value:
HKLM\System\Current Control Set\Control\TerminalServer\Wds\icawd\thin16\MaxLVBMem
The MaxLVBMem value specifies (in bytes) the maximum memory that thinwire will allocate for the frame buffer.
It can be modified using twconfig.exe; however, twconfig will not let you specify a value larger than 7680000 bytes.
The remaining 8.4 MB is taken up by other things that we have little or no control over (e.g. GDI itself, printer drivers, etc.).
Microsoft will not modify the 16 mb session limit before WHISTLER. Now, what we found out is that this key can be modified to other values. So when we need to support 4 monitors, we calculated the required memory in bytes (1280 x 1024 x 2 words (or 16-bit) x 4 monitors) and this equals 10,485,760. So, this was the value we entered into this key. And it worked. So, keep this in mind."
As I said it may be fixed with Windows 2003 but I could not try. Microsoft, if they read this post, can shed some light on this.
Cláudio Rodrigues, MVP
Windows 2000/NT Server
Terminal Services
Remove Comment 75291

written by dcaddick

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