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Parameter is/use_uds

Former Member
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Hello Gurus - Does anyone out there uses the "is/use_uds = 0" parameter in any of your SAP instance? From SAP's documentation this parameter is only for Linux OS, and for AIX this parameter should be set to 0 (we are using AIX). We have had a situation in one of our dialog instance where we exhausted the number of network socket connections, particularly sapstream3303 gateway conections.  SAP support has recomended a solution describe in SAP note 488036, basically setting is/use_uds = 0 (default value = 1). Does anyone out there using is/use_uds = 0 in an AIX environment? If so, did you notice any performance improvement or did the new parameter value resolved the issue ?

Please let me know.

Thanks.

Octavio

Symptom


Caution: This note applies to AIX operating systems only.

All
applications may temporarily experience the problem of no longer being able to
activate R/3 enqueues. The following symptoms occur in connection with this
problem:


  1. 1. Temporary syslog entries "Unable to reach central lock handler"
    1. 2. Dialog boxes in the application describe the problem of communicating
  1. with the central instance.
    1. 3. The message server trace file (dev_ms) logs that the message server
    1. terminates the connection to the dispatcher of the central instance in a
  1. controlled manner, as this connection can no longer be reached.
    1. 4. A connection termination to the message server (keyword MBUF down)
    1. appears in the dispatcher trace file of the central instance at exactly the same
    time.

Other Terms

Enqueue, lock, lock table

Reason and Prerequisites

In the AIX operating system, the dispatcher and the message server process
communicate by Unix domain sockets instead of a TCP/IP line. The maximum size of
the Unix domain socket buffer is restricted to 4KB by the operating system. In
the case of a large load, this can result in a buffer overflow on the system,
and subsequently the symptoms described above.

Solution

Change the internal system communication to TCP/IP. To do this, follow the
steps below:
Kernel releases up to and including 6.40:

  1. 1. Stop the system.
  1. 2. Log on as user root at operating system level.
    1. 3. Create the following file: /tmp/.sapstream<sapmsxy> where
  1. <sapmsxy> is the PORT NO. of the message server.
   For example: The following entry exists in /etc/services for the system
name C11 and system number
00:

            sapmsC11                3600/tcp.

Therefore, the
file name in this example should be /tmp/.sapstream3600 and MUST belong to the
root user.

ex

Accepted Solutions (0)

Answers (1)

Answers (1)

former_member188883
Active Contributor
0 Kudos

Hi Octavio,

Please check SAP note 1578475 - Checking if TCP/IP is used on AIX


The parameter is/use_uds is used to ensure TCP/IP protocol is used instead of UDP.


So as suggested in SAP note 488036 - Unable to reach central lock handler, AIX only

set the parater for is/use_uds = 0. ( implies to use TCP/IP only)


Hope this helps.


Regards,

Deepak Kori