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ASCS and SAPGUI Loadbalance

Hi there,

i have a problem to understand the behavior of the SAP GUI reagarding ASCS and loadbalancing.

We have the following:

ASCS (messageserver) on SERVER0 SystemNr. 60

Instance1 on SERVER0 SystemNr. 61

Instance2 on SERVER1 SystemNr. 62

In SAP GUI i created a entry and set instancenr. to 60 (Messageserver is running on 60).

I'm able to logon to the system now correctly using the messageserver running on 60.

In services the MS port is maintained like that:

If i now go to properties the SAP GUI tells me that the instancenumber has changed to 62

(which is the Appserver1).

If i press ok, the SAP GUI will change the entry to instancenr. 62.

I think i have a problem now, because from now on my client is only using APPSERVER1 directly to logon and not longer the messageserver??

If im switching which Appserver is contained to the LOGON Group, the GUI switches the Instance Nr. from 61 to 62 and back.

For example only SERVER0 with 61 in the SMLG group, the GUI switches to 61. If i remove SERVER0 from SMLG and

only add SERVER1 with 62, the GUI switches to InstanceNr. 62.

Can somebody tell me what i'm doing wrong? Or why the GUI is acting like this?

Or is the GUI always contacting the messageserver on 3660, nevertheless what is written in the grey "Instance Number" field,

because sapMSSID is set to 3660 in services?

GUI 7.30 PL 10



Former Member replied

The parameters you need for connecting to a message server is:

     message server hostname

     and the SID of the system.

The SID of the system is used to find entry sapmsSID /windows/system32/drivers/etc/services to determine the right port for the service. The service name does not contain any part of the instance number the message server is using.

Hence can use a tcp port of your choise  for sapmsSID with following restrictions:

  1. the port must be free on the message server host
  2. on all computers where you have programs running which connect to this message server, you have to define the entry sapmsSID in the file /windows/system32/drivers/etc/services



PS: The instance umber in above screen copy is only informational for a selected server and has no meaning when using logon groups

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