SAP Note 23538 - Problems due to inconsistent host name notation

Symptom:

1. Error messages appear in the syslog (for example, "enqueue server is not known by the message server" or "enqueue server not available"). No background server is found. According to the R/3 background job, external programs terminate even though no errors occur when they run.

2. When you start R/3 on a central system, the connection to the Oracle database does not work:
The dev_w trace files contain the following message:
*** connecting via TWO_TASK = T::
*** ERROR sql 6108 performing con
*** ERROR ThSendErrMsg: db_connect ...

3. There is a naming conflict with regard to the use of upper case and lower case in the host name used in transaction SM51.

4. A short dump occurs when you display DB12.

5. Problems occur when you schedule both 'operation mode switching' and background jobs on explicit hosts.

6. The CCMS system program SAPMSSY6_RSALSUP5 is disabled. Transaction RZ03 displays a corresponding alert.

Other Alerts YELLOW SAPMSSY6 RSALSUP5 Disabled

7. Upgrade problems
When you carry out an upgrade or install an add-on, the process of starting R/3 systems with STARTSAP.EXE fails with return code '-1'.

8. Installation problems
The process of using STARTSAP to start the SAP system fails. Section from CENTRDB.LOG:
INFO 1999-01-01 11:38:29 DBR3START_NT_ORA SyCoprocessCreate:1148
Creating coprocess H:\usr\sap\CAI\sys\exe\run\startsap.exe ...
INFO 1999-01-01 11:45:14 DBR3START_NT_ORA ExecuteDo:0
RC code form SyCoprocessWait = -1 .

Other terms

host name, TCPIP, DB12, SM51, startsap, DNS, name resolution, hosts

Reason and Prerequisites

In general:
Windows (NT, 2000, 2003, XP) distinguishes between the 'computer name' (Control Panel -> Network) and the 'host name' (Control Panel -> Network -> TCP/IP Protocol -> DNS). The name specified during NT installation will only be used as a 'computer name' for addresses within the LAN manager, while the 'host name' is used for addresses in TCP/IP. The 'computer name' exists in UPPER CASE only , while the host name is automatically set in lower case during the network configuration.
The main part of R/3 network communication is implemented by TCP/IP on the basis of the 'host name'. Within the R/3 system (for example, CCMS), this TCP/IP name is treated as CaSe SeNsItIvE. The errors mentioned above may occur if, during the upgrade or in any form of the dialog with R/3, the TCP/IP 'host name' (hereafter simply called the 'host name') is used in a different uppercase and lowercase format in R/3 profiles.

Especially for phenomenon no. 2:
The aforementioned symptom is possibly a specific instance and is caused by the inconsistent notation of the SAPDBHOST and SAPLOCALHOST profile parameters compared with the host name from Windows NT:
The work processes read SAPDBHOST, determine that the name is different from the host name (command prompt: "hostname") and SAPLOCALHOST, and - by means of TWO_TASK in TCP/IP - attempt to make the connection to a host that does not exist.

Solution

• ALL references to the host name in SAP R/3 profiles (for example, rdisp/btc_name, SAPDBHOST, SAPLOCALHOST) must contain the TCP/IP host names! Adjust the profiles accordingly. Then restart the R/3 system including SAP Services. You can use the command line command "hostname" to determine the TCP/IP host name. To check that your changes are effective, display the host name in transaction SM51.
  
  Of course, you should also enter the TCP/IP host name in the HOSTS file. Alias entries in the hosts file are not sufficient for this and should - if possible - be avoided if the alias contains the same host name, but it is written in the other notation.
  It is a good idea to create a HOSTS file (see below) that includes the addresses and TCP/IP host names of all application servers in a distributed R/3 system. Then copy this HOSTS file to all applications servers in the %windir%\system32\drivers\etc directory. By doing this,

• you reduce unnecessary network traffic for host name resolution using DNS or WINS, and

• you make a unique host name source available to each application server.

Since the message server maintains a host name cache, you must stop and restart the R/3 system after you change the HOSTS file (in order to activate the changes).

• Multihomed computer
  For computers with several network cards, a separate, unique TCP/IP HOSTNAME must be assigned to each network card. You cannot use one name for several network cards (IP addresses). In this case, you must add the addresses of the second adapter to the HOSTS file and specify a second host name there. This host name must be unique, in other words, it must not simply differ with regard to the upper case and lower case of the host name of the first network adapter.
  Information about the second network adapter (NIC) should also be available to other applications servers. Therefore, you should add the HOSTS file to the other instances. The following example shows how the HOSTS could look on each application server in a distributed R/3 system:
  
  127.0.0.1 localhost
  111.111.111.1 centrl #central instance
  222.222.222.1 centrl_A #2. NIC of central instance
  111.111.111.2 apsrv1 #application server 1
  222.222.222.2 apsrv1_A #2. NIC of application server 1
  111.111.111.3 apsrv2 #application server 2
  222.222.222.3 apsrv2_A #2. NIC of application server 2
  ...
  
  If you encounter difficulties when assigning host names to the IP addresses of a computer, refer to Note 83200.
  

• If the procedure mentioned above is not successful, the parameter SAPLOCALHOST may exist again in the user environment of the user who starts the R/3 kernel. The SAPLOCALHOST, which is set in the environment in this way, overwrites the TCP/IP host name that is determined by the R/3 system in the operating system. Use the "SET" command to scan the user environment, or the kernel environment in the registry (HKML\Software\SAP\\Environment), for the parameter SAPLOCALHOST and, if necessary, correct the notation. After you change the value, you also have to stop and restart the R/3 instance (including SAP Services) here.
  

Exception SAPGLOBALHOST:
The parameter SAPGLOBALHOST will be set in capitals due to reasons related to the technical installation, but it is NOT treated as case sensitive. Therefore, it does not matter whether SAPGLOBALHOST is in upper case or lower case.