'Antwort: RE: Antwort: RE: Central instance questions'

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List:       mysap-linux-general
Subject:    Antwort: RE: Antwort: RE: Central instance questions
From:       "Dietmar Stein" <DStein () phoenixcontact ! com>
Date:       2002-06-25 8:56:55
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Hi Koray

... I think I have to tell the whole story, because you are going in a
different direction ...

We are using SAP R/3 4.6C SR2 on Linux / Oracle and SAP 6.10 with BW3.0 and
CRM3.0 on Linux / Oracle. We like to make our R/3 system redundant and
hardware failure tolerant.

I am currently testing with a test installation and its configuration is as
follows:

- Host 1 keeps database and first installed CI
- Host 2 and 3 are dialog instances (R3SETUP -f DIALOG.R3S)
- Host 4 is installed with CENTRAL.R3S but without database

The system number is always 01 and the system id is always Z01. Directories
/usr/sap/Z01/profile, /usr/sap/Z01/exe and /usr/sap/Z01/global are exported
by Host 1 and shared to the others (rw access).

The currently working enviroment is as follows:

- Host 2 and 3 are working as dialog instances (application servers)
- Host 1 and 4 are working as central instances
- Host 1 serves the database

If one dialog instance "dies" (hw failure, whatever) you will get a timeout
or broken connection error within GUI but you can reconnect to second
dialog instance (I have created a logon group with host 2 and 3). So, could
you load balance the "two CI" like the two dialog instances or will the
dialog instances try to connect to the died CI if their logon group was
created on that (died) CI before?

I created the logon group on host 1 but switched CI to host 4 and stopped
the processes on host 1; the logon group still exists and is working ... or
may that be a bug?

Dietmar

                                                                                      \

                      "Koray Taser"                                                   \

                      <koray.taser@t-syst         An:      "Dietmar Stein" \
                <DStein@phoenixcontact.com>                                    
                      ems.com.tr>                 Kopie:                              \

                                                  Thema:   RE: Antwort: RE: Central \
                instance questions                                    
                      25/06/02 10:43                                                  \

                                                                                      \

                                                                                      \

Hi Dietmar,
you may need to install a second instance (APPLICATION SERVER instance)
on the same host with a connection to the central instance.

You should care that second instance's system number must be different from
the central instance (usually 00).
You can use any number up to 99...

I just realized that you talk about a second host. Normally a central
instance without database, behaves like an application server instance.
which SAP and DB version running on your systems?

-----Original Message-----
From: Dietmar Stein [mailto:DStein@phoenixcontact.com]
Sent: Tuesday, June 25, 2002 11:37 AM
To: Koray Taţer
Subject: Antwort: RE: Central instance questions

Hi

Thanks for your answer, but there is one question left: how do you install
two central instances (if you do not call them CI already)? I have
installed database server with central instance on the same host. Later on
I installed a CI via R3SETUP -f CENTRAL.R3S on a second a host, without
database. Now both "CI" are running ...

Dietmar

                      "Koray Taser"
                      <koray.taser@t-systems.co         An:
                      <linux.general@listserv.sap.com>
                      m.tr>                             Kopie:
                      Gesendet von:                     Thema:   RE:
                      Central instance questions
                      linux.general-admin@lists
                      erv.sap.com

                      25/06/02 10:29

yes it is possible to run 2 central instance on the same db server.
but you can not call the second instance as a central instance, ony one
central instance exists on a SAP landscape.

You can also be set up load balancing but I must say that, if your server
is strong enough, it's better to run only one central instance on DB server
with increased number of processes.

regards,

Koray Taser

-----Original Message-----
From: Dietmar Stein [mailto:DStein@phoenixcontact.com]
Sent: Tuesday, June 25, 2002 11:18 AM
To: linux.general@listserv.sap.com
Subject: Central instance questions

Hello

Is it possible to have two central instances run against the same database
server? And, if yes, could the central instances be load balanced, too?

Dietmar

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