What is central instance..........

hi,
I am new to the SAP . i want information about what is central instance and dialog instance. what are their roles in SAP System.
Regards,
sridhar M

Hi Sridhar
Though your question looks simple but i suggest to read following link
http://www.oreilly.com/catalog/sapadm/chapter/ch01.html
The central instance is a combination of hardware and software. It contains a physical server (the application server) and numerous software components, including a message server, a database gateway (a pre-established connection between SAP and Oracle--or another database), and various update, enqueue, dialog, and spool facility software. In most generic SAP architectures, there are numerous application servers but only a single central instance. However, in addition to managing the SAP interfaces, the central instance can also serve as an application server.
hope its fine.
Thanks..
PS : Award points if helpful

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How to determine central instance

Dear all,
I have the instances as follows.
DEVBMGS00 for production.
DEVBMGS25 for development
DEVBMGS00 for Quality
Now my question is:
Can any1 tell me what is central instance how to determine the central instance out of the three?
<removed_by_moderator>
regards,
Ashutosh
Edited by: Julius Bussche on Jun 24, 2008 8:27 AM

No... you didn't understand...
You have 3 systems...
DEVBMGS00 for production.
DEVBMGS25 for development
DEVBMGS00 for Quality
each system has a central instance as each system needs to have an enque process for handling the locks on each individual database. in a system (say one of the three above) you can have more that one instance the central instance is the one that holds the enque process.
Regards
Juan

Central instance..

Hi guys & gals,
What is Central Instance with example??
Regards
JIku

Hi Jiku,
mySAP is composed of several cooperating services that may be run on a single server or may be distributed across several servers in a cluster. Some of these services have redundancy built into them, while others do not and represent single points of failure in the SAP environment. The
SAP Central Instance (Enqueue and Message server for ABAP), the SAP System Central Services (SCS) Instance (Enqueue and Message Server for Java), the Database server, and the NFS server represent single points of failure (SPOF) and are the services that LifeKeeper will protect.
The SAP Central Instance (CI) is a standalone SAP Basis unit which provides services used by clients connected to the SAP system. Among these services are the Message server and the Enqueue server, which run only on the single SAP Central Instance. The Message server maintains a list of all available resources in an SAP system, determines which instance a user logs on to during a client connect, and handles all communication between SAP instances. The Enqueue server is used by SAP to administer the lock table in a distributed SAP system. If the CI
server hosting the Enqueue service fails, all SAP transaction locks that have not yet been committed are lost. R/3 guarantees that no user can perform a transaction while the Enqueue service is unavailable in order to guarantee database consistency. Placing the Enqueue and Message services together on the CI is recommended by SAP since the Message service must always access the Enqueue service for inter-process communication. These services provide critical SAP functions that, by existing only in the SAP Central Instance, suffer from being a single point of failure in the SAP environment. Obviously, the CI, which contains the Enqueue and Message services, needs to be restarted as quickly as possible following a failure so that normal operations can resume.
<b>Reward Points if Useful</b>
Regards
Gokul

Differnce between central instance ,dialog instance and application instanc

Hi all
Please explain me what is central instance. what is it differnce betwenn the
other instances like dilaog instance ,apllication instance.
What is the exact use of having many instances ?
regards
Sanjeev.S

Hi Sanjeev,
First of all let me Clarify between Cental instance(CI)and Central Service instance(SCS). When you install NW04/NW04s systems on WIndows, when you open you windows console, you would first find the SID name that you have installed and when you expand this you'll find 2 instances. When you expand the first instance you'll find that there are message server and Enqueue server listed. This instance is called as Central Service instance or simply called SCS. You can look at the folder structure /usr/sap/<SID>/.
Now the second instance is called as Central instance, when expanded you would see a SDM, a dispatcher and a server node. This is the instance which processes all your requests.
Now answering your question about Dialog instance, When the CI is overloaded, i.e. your dispatcher is overloaded and your server is overloaded , you would install a dialog instance, which means that the database need not be installed for the Dialog instance and it can be on any system. While installing the Dialog instance it would ask you which Cental instance I have to refer, then you would be giving the necessary system to which you have created a dialog instance.
Giving a graphical view,
SID < J2E>
< DATABASE>
<hostname>00 message server
                        enqueue server
<hostname>01 SDM
                        dispatcher
                        server0
This is your one SAP system. Now you feel that this system is overloaded with lot of users, any there are many user who will be logging in again, so what you would do is install a dialog instance which would be referiing to J2E database but will have its own dispatcher and server0. SDM, message server and enqueue server are only one per systems.
Now the dialog instance for J2E would look like this
SID < K2E>
<hostname2>01 dispatcher
                         server0
Dialog instance is mainly for load balacing, now you can access the database of J2E by typing a different URL i.e. of K2E and hostname2 but still accees the data of the J2E. The communication between Dialog and Central instance is thru message server.
In case you find it difficult to push thru, please let me know..

Best Practice to migrate existing Message/Central Instance to new hardware?

I've done some searching for this, but it all seems to be fairly old (I found one decent thread from 2008, but it just seemed outdated). I would like to get some updated info & suggestions on a process to follow for this task.
Here is some info about the current config:
I have an existing SAP ERP 6.0 EHP5 system. SID "XYZ"
Everything is currently running on Windows x64.
ABAP only config.
It is currently setup as a distributed system.
DB server is SQL, which is running on its own hardware as a dedicated DB server. I don't need to touch this.
Uses logon groups to distribute the load between 3 App servers.
One of the App Servers is setup as the Message/CI server. This is what I am wanting to move to VM hardware.
The other two App Servers are setup just as Dialog Instances. VM already. I don't need to touch these.
What I am wanting to do:
I am wanting to migrate the existing Message/CI server to VM hardware to get the current Message/CI system off of very old hardware.
I need to keep the system with the same name & IP.
I do not need/want to mess with the DB server at all.
Need to minimize downtime as much as possible.
I do NOT want to go to an HA environment. That is a different project for the future.
Suggestions? I would like to hear what some of you have done.
Minimize downtime? I have a short maintenance window of a few hours coming up in the next few months, and would like to do this changeover during that downtime.
How do I handle setting this up on the new hardware using the same name & IP, especially with the existing system still running.
What I think I need to do: (Some of these may be out of order, which is why I'm asking for suggestions)
Setup new Windows VM server, named differently than current Message/CI server (Done already).
Run SAPINST to run Global Host Preparation on the new Windows VM server.
Run SAPINST to setup ASCS Instance on the new Windows VM server.
Skip the Database Instance installation, since I already have one running.
Run SAPINST to setup Central Instance on the new Windows VM server.
Copy all of the appropriate profile parameters that were on the old server.
Start SAP and make sure everything is running and working correctly.
Copy all job, spool files, etc. from the old server.
What needs to be done in between those steps for the server rename & IP changes?
Which of these steps can I do in advance of my maintenance downtime window, without it affecting the currently running system?
I have a test environment that I am going to test this with. I'm just trying to get a jump start on my instructions, so that I can hopefully do this quickly and easily. I'm very comfortable doing the installs. Just needing some guidance on how to handle this case.
I'm open to suggestions, and any links you can send my way that show some more recent success at doing this. Everything I keep finding talks about doing the migration for the DB. I am not migrating my DB. It is staying where it is. I'm just wanting to migrate my Message/Central Instance to a VM, without affecting the users, and hopefully them never noticing the changes.
Thanks!

If you're using VMWare, there is a tool provided to virtualize existing systems. Basically it makes a copy of the old system (while it is down) and recreates it as a VM with the same name, IP, etc. I haven't double-checked to see if this process is 'officially' supported by SAP, and I don't know the technical details about how it's done or how long it will take (VMWare is managed by the Network Operations group in my team, so as the SAP sysadmin I'm basically a customer of theirs). However, we have virtualized a few smaller systems that needed to get off failing hardware in a hurry and it worked very well, so I would expect it would for an SAP dialog instance as well. As you're not copying a database, just the app server, it probably would fit within your maintenance window.
If this route works for you, then there is no need to actually install the SAP system on the VM instance... you just copy the old server as-is, then make any adjustments required due to no longer needing old drivers, etc, plus potentially having different memory parameters.

Installation of central instance - memory settings

Hi All,
I have a question about the memory settings reg. the ABAP / Java Add-In installation (Central system).
Installation of CI:
When I install the central instance, I provide a value for the Instance Memory Management.
Installation of DI:
In the step where I install the database instance, I provide again a value for Instance Memory.
Q1: The memory value for the Central instance later is visible in the profile for the CI. But where does the DI value go? How could I change it?
Q2: The value for the Java JVM (heap size) - is this value additional to the value of the CI, or part of the CI's memory. So could I set heap size to 2M while the CI's memory is set to 1M?
Any hints are appreciated.
Thx.
KB
System
- Win2K (Win32)
- Oracle

Q1: The memory value for the Central instance later is visible in the profile for the CI. But where does the DI value go? How could I change it?
--> You can ignore this, there is no INSTANCE memory for your database. If you want to configure the memory settings for your RDBMS software it'll depend on what software it is... For Sql Server it's in the Enterprise Manager in Oracle you can edit the init<SID>.ora file...
Q2: The value for the Java JVM (heap size) - is this value additional to the value of the CI, or part of the CI's memory. So could I set heap size to 2M while the CI's memory is set to 1M?
--> This value is specific to your JVM heap, so it's not additive or related to your CI.

How to add a java dialog instance to Java central instance of SAP CRM

Hi Gys,
I have installed a new dialog instance for the CRM Java landscape for the version 7.01 .
CRM Abap instance is seperate and its data accessed by Jco connection by central instance but not dialog instance . Could you please let me know if any configuration steps to be followed.
Thanks in advance
Sudhakar

Could you describe your problem a little bit more.
I have installed a new dialog instance for the CRM Java landscape for the version 7.01 .
CRM Abap instance is seperate
Ok, sounds like 2 Java instances and one ABAP instance.
and its data accessed by Jco connection by central instance but not dialog instance.
This is where I get confused.
Do you have one or more ABAP instances?
What is your actual problem (what do you want to do)?

Difference Between central instance And application instance

Hi every body can any one tell me that
what is the difference between Central instance and Application instance.
If i am using 4.7 ee with orcale data base.

Check these links
http://oreilly.com/catalog/sapadm/chapter/ch01.html
Basically these terms comes when you are working on live servers where all the users log into to do their daily work.
We says when we want to distribute the workload on servers we requires central instance and application servers.
Normally it is not known to common users where they are logging into...but they can login directly usign the specific Instance details of servers.
Please see this also
http://help.sap.com/saphelp_nw2004s/helpdata/en/c4/3a64e8505211d189550000e829fbbd/frameset.htm

Central Instance in a Windows2008 MSCS with Oracle

Hello,
I have just finished the installation of a SAP Solution Manager with MSCS on Windows2008 and Oracle. This is my first MSCS, so I'm a little bit confused. I think almost all the things work right except the central instance. i explain:
I have the first node (node1) and the second node (node2) working fine. To check the MSCS installation, I shutdown node1 and make remote logon in node2 to see what's happening. And there are two remarkable things:
1.- Service/Instance SAP<SID>0 allways fails. If I startup it manually it works fine --> I suppose I have to add somewhere a retry after a delay.
2.- The central instance <hostname>20 doesn't exist in node2. So I cannot logon because there is no central instance. I only have the central instance in node1. I have read several times the documentation of the installation and I haven't found anything about installing the central instance in the additional MSCS node. It only says about the two options of the central instance installation: On a MSACS node or in a host outside MSCS (Not our case). Have I understood right?
Besides, I think the java instance is wrong too, I only have it in the first MSCS node.
Any help?
Thanks and best regards,
Ana

Hello Ana,
> 1.- Service/Instance SAP<SID>0 allways fails. If I startup it manually it works fine --> I suppose I have to add somewhere a retry after a delay.
check the property of SAP Service/Instance resource, under advanced tab, is "restart" option ticked with threshold and Period
defined. e.g threshold = 3, Period = 900 seconds
> 2.- The central instance <hostname>20 doesn't exist in node2. So I cannot logon because there is no central instance. I only have the central instance in node1. I have read several times the documentation of the installation and I haven't found anything about installing the central instance in the additional MSCS node. It only says about the two options of the central instance installation: On a MSACS node or in a host outside MSCS (Not our case). Have I understood right?
Your understanding is correct, The ABAP central instance (now without the message and enqueue servers) is generally installed locally on one of the cluster nodes with a second, identically configured dialog instance on the remaining cluster node. You can find more information in the installation guide.
As message server and enqueue is running on ASCS, the central instance is not required in order to logon to SAP system.
If you have issue logon to system when central instance is not running, please check you have at least one dialog instance started besides the ASCS instance.
Best regards,
Qingqing Wang

Why do we do kernal upgradation in central instance only

Experts,
I have a question. Why do we do kernal up gradation in central instance only? what about other instances? How the up gradation takes place in other instances?
points will be awarded to all helpful answers.
Thanks in advance.
Rajesh

Hi,
Whatever the other two friends have explained is correct. We do kernal upgrade only on CI when the Operating systems of the CI and the Application Instances are same.
if the CI and AI are in different operating systems then we may have to upgrade kernel in both CI and AI.
Sapcpe.exe would synchronize the kernel only when the SAP systems have homogenous OS.
Reward points if useful.
Thanks,
sree

Change name of Central Instance

Is it possible to change the name of a Central instance? I have created a number of instances on our production machines, but the installation program only allows me to enter a description for an instance. The names of the instances are currently SERVER, SERVER1, SERVER2, etc ...
I already tried to change this in the JFSERVER.ini file:
[JFSERVER]
ServerName=CSS01-PRS02
But this didn't fix the problem.

By default, the name of the instances is also the physical folder name that is the root for the instance. This is buried in the "Central\Control\Install.ini" file, the "jfserver.ini" file for each of the instances, and probably other places. It might be possible to find all the locations in the various files (& perhaps Registry entries) where it is referenced but I doubt if it is worth it.
What I ended up doing was to not worry about the physical folder name and just changed the "WindowTitle" value in each instance's jfserver.ini file. This allows you to customize what shows in the drop down list when selecting an instance as well as what is in the Central Control window title bar for the instance.
Are you sure that the installation process doesn't allow you to specify the name when it is doing the installation? It has been a few months since I did my last install but I seem to recall that the name could be specified.

Why do need to install a Central Instance while installing WAS ABAP+Java :|

Hello all,
I've installed SAP WAS ABAP+Java 6.0 today.
In case of WAS ABAP+Java, there is one database but ABAP and Java have seperate schemas inside it.
Comparing the installation process with Installation of WAS Java (Java Stack/Engine only), wherein after installing few pre-reqisites like JDK, SQL Server (in my case) and then portal....I believe it created a schema for Java.
But in WAS ABAP+Java, what is the need to install a Central Instance first and then a database instance?
Awaiting Reply.
Thanks and Warm Regards,
Ritu R Hunjan

UPDATE... Gone onto the mac store today and now in the purchase tab Lion has been removed so looks like I have not even purchased it... I did a search for it in the store and instead of saying "Installed" - its giving me the selling price... Just like it does when you first purchase the software!!
What's going on?... HELP!!!

Windows Central Instance ABAP+JAVA plus UNIX ABAP dialog instances ?

Hi everybody,
we are an SAP software partner and provide SAP complementary software on UNIX and Windows platforms.
Part of our software (a gateway) needs to be installed on the SAP application server.
In order to setup a cross-platform test environment for our developers, I was thinking about extending the existing SAP ERP 6.0 Windows-based Central Instance (IDES, Oracle, usage types ABAP+JAVA) by multiple ABAP dialog instances which run on different UNIX flavours (Solaris, AIX, Linux).
I searched the SAP Notes and found nothing which could confirm my plans, as this is quite an unusual setup and heterogenous systems are usually the other way round (CI on UNIX, DI on Windows).
SAP Note 1067221 however mentions that DIs on different OS platforms are only partly supported, but it seems this is only valid for JAVA DIs?
As I need only ABAP DIs, I hope my plans are fine?
Many thanks for your feedback
Markus

> I searched the SAP Notes and found nothing which could confirm my plans, as this is quite an unusual setup and heterogenous systems are usually the other way round (CI on UNIX, DI on Windows).
Well - what is "usual" depends on the requirements
It's possible to do that. Technically there's no difference whether an application server is Unix or Windows based.
There are, however, a few things to take care of:
- if your system is non-Unicode, sorting algorithms are different on different platforms. Unicode systems use ICU which is cross-platform
- if you want to automatically distribute your kernel on system start you will need to create a "share" on the Windows machine and make it accessible from the various other platforms. You can, however, ensure "manually", that you use the same kernel patchlevels on all systems, then this is not needed
- Windows is LittleEndian whereas most Unix systems are BigEndian, depending on if you exchange data between those systems (means, binary data, files through NFS) the programs must be aware of the fact, that a file can be either LE or BE.
Markus

Central Instance didn't start after Kernel Upgrade

Hello,
I've made a Kernel Upgrade for a Solution Manager with kernel version: release 7.01, 64-Bit Unicode on Microsoft Windows Server 2003 Enterprise x64 Edition.
When I wanted the SAP instance, Central Services instance started, but Central Instance didn't.
In the sapstart.log file the following error: "SAPSTART finished successfully on , but at least one process doesn't run correctly:
sapstart.exe=>sapparam (1c): No Profile used."
The file "dev_w0" says the following:
in_ThErrHandle: 1
M ThIErrHandle: new stat of W0 is WP_SHUTDOWN
M ThIErrHandle: I'm during shutdown
M PfStatDisconnect: disconnect statistics
M Entering ThSetStatError
M ThCallDbBreak: use db_sqlbreak
C SQLBREAK: DBSL_CMD_SQLBREAK: CbOnCancel was not set. rc: 1
B db_sqlbreak() = 1
M ThIErrHandle: don't try rollback again
M ThShutDownServer: shutdown server
M PfStatIndInit: Initializing Index-Record
M PfWriteIntoFile: copied shared buf (0 bytes) to local buf
M ThIErrHandle: do not call ThrCoreInfo (no_core_info=0, in_dynp_env=0)
M Entering ThReadDetachMode
M call ThrShutDown (1)...
B Disconnecting from ALL connections:
B Wp Hdl ConName          ConId     ConState     TX PRM RCT TIM MAX OPT Date     Time   DBHost
B 000 000 R/3              000000000 INACTIVE     NO YES NO 000 255 255 20091025 070423 BCE-SAP-SRV01
B 000 001 +DBO+0000      000000476 DISCONNECTED NO NO NO 000 255 255 20100114 204611 BCE-SAP-SRV01
B Disconnected from connection 0
B statistics db_con_commit (com_total=730465, com_tx=135964)
B statistics db_con_rollback (roll_total=9630, roll_tx=0)
M ***LOG Q02=> wp_halt, WPStop (Workproc 0 10744) [dpnttool.c   334]
I didn't really know what to do in this case... Could you please give me a hint?
I also want to tell you that the Database Instance (MSSQL server) disappeared from SAP MMC, but I checked in SQL Server Configuration Manager and the processes are running...
Thank you in advance for your help,
Noemi

Please check the Wndows event log, you may have run into the problem described in
Note 1402510 - Resolving SideBySide Assembly Errors
Note 1375494 - SAP system does not start after applying SAP kernel patch
Markus

What is an Instance in SAP?

Dear,
What is an Instance in SAP?
Thanx and Regards,
Mohammad Nabi

hi,
Instances
SAP instances are defined during the installation of the SAP system.
The term instance is often used synonymously with server or application server in the SAP system. This depends on the selected installation environment. You can install multiple instances on one application server.
An SAP instance defines a group of resources such as memory, work processes and so on, usually in support of a single application server or database server within a client/server environment. Application servers share the same memory areas and are controlled by the same dispatcher process.
An SAP instance is handled by CCMS as a unit. A user logs on to the SAP system using an instance.
An SAP system can consist of one or more instances, such as an SAP system with a single instance with only one central server or a client/server system with two or more separate instances.
For each SAP instance:
·        Separate directories are defined on the UNIX, AS/400, or Microsoft Windows NT server on which the instance is to run
·        Shared file systems can be used
·        Entries are created in operating system configuration files (/etc/services, /etc/sapconfig...)
·        Communication entries are created in the host
·        Start and system profiles are created
·        Operating system users are installed
regards
sadhu kishore

What is central instance..........

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