Why the memory above 4 GB is not used by the Windows 2003 Std. x64 Ed. with Terminal Services on it.
Posted on 2009-07-13
Summary: Windows server 64-bit dedicated for access via Terminal Services uses only 4 of the 6 GB of memory. See more details below.
We are observing the performance problems in situation when more than 10 users try to use SAP Bussiness One clients (version 2007) via Terminal Services. We have used the older version of SAP Bussiness One earlier and the experience showed that it is rather memory greedy. Because of the assumed increase of the number of users we had anticipated the neccessity to add memory; hence, we have chosen the 64-bit version of the Windows server where the clients are to be run.
The SAP clients are executed on the computer dedicated to access via TS. When 11th user does connect via TS and run the client, the server start to use the disk intensively -- it is likely that it swaps memory intensively. The task manager show that the system uses slighgly less then 4 GB of the physically available 6 GB RAM.
More details: The SAP Bussiness One uses Microsoft SQL Server on another machine. When the 11th user has problems with starting the SAP client, it is possible to run another SAP client on the machine where the MS SQL Server is located without problems, at the same time. Also, other users can log via TS to the dedicated TS machine and no problems are observed until they try to run the SAP client. In other words, it seems that the access to the database does not cause the problem, nor the number of users from the SAP point-of-view, nor the number of TS sessions via the dedicated TS server. It seems that it is the combination of using of the more memory-greedy applications on the dedicated TS machine.
It is not clear whether the problem is caused specifically by the SAP client application or if it would be observed when running whatever application with similar memory requirements (one clients takes about 300-500 MB of memory). It looks to me as if Terminal Services had some option of how much memory they can use (just my wild guess).
For the case it was interesting, the boot.ini content (placed on disk d: of the dedicated TS machine) is:
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Windows Server 2003 Standard x64 Edition" /noexecute=optout /fastdetect
Thanks for any help,
P.S. I am starting to loose the last few hairs that I have. (It is not going to change my image too much as there is not too much to loose. It is just description of my mental status. ;)