How to setup Active-active cluster for Application ABAP (Not Database)?

[Former Member]

Dear Experts

I have a issue as following :

I have three server in landscape of Production model, so called server A, B and C

I want to implement cluster for Application ABAP as active-active cluster model ( On server A and B) to share workload between this two nodes (run on RedHat 64bit)

And then, On server C, I implement to install Database Oracle 10G R2. (run on Redhat 64 bit)

My desire, with this model, my user can access SAP system via A and B (If A downed, My all user can access via B)

I read document for Installation Guides but I donu2019t understand following issue:

And my questions :

When I run ./SAPINST -> SAP ERP 6.0 EHP4 Ready -> SAP Application Server ABAP -> Oracle -> I saw :

+Distribute Sysem

+H-A System

Question 1: I donu2019t know, i can choose which model (Distribute or HA ?) to install as my desire ?

If choose HA model, includes:

+Central Service For ABAP (ASCS)

+Database Instance

+Central Instance

+Dialog Instance

Question 2 : I donu2019t know where ASCS installed ( on server A or B or C)?

And then where Database Instance installed ( on server A or B or C)?

And finally Central Instance and Dialog Instance (on server A or B or C)?

Please guide me to implement this issue

Thanks and regards

[Former Member]

thanks all

This problems have resolved

[Former Member]

Hi Sinil

Thanks for your support

and finally , I logged in SAP through Group Logon in Logon Pad -> OK

But when i run tcode DB13 to run Action Pad : Cleanup Logs, Check and Update Optimize Statistic ....etc -> with Cancel status in tcode SM37 -> with error in tab Job Log below

******************************************************************************************************************************************

Job started

Step 001 started (program RSDBAJOB, variant &0000000000019, user ID DDIC)

No application server found on database host - rsh/gateway will be used

Execute logical command BRCONNECT On host database

Parameters: -u / -jid STATS20101214002434 -c -f stats -t ALL

SXPG_STEP_XPG_START: is_local_host: rc = 403

SXPG_STEP_XPG_START: host = database

SXPG_STEP_XPG_START: is_local_r3_host: rc = 802

SXPG_STEP_XPG_START: RFC_TCPIP_CONNECTION_OPEN: rc = 1003

SXPG_STEP_COMMAND_START: SXPG_STEP_XPG_START returned: 1.003

SXPG_COMMAND_EXECUTE(LONG)

<timestamp> = 20101214002506

COMMANDNAME = BRCONNECT

ADDITIONAL_PARAMETERS = -u / -jid STATS20101214002434 -c -f stats -t ALL

LONG_PARAMS

OPERATINGSYSTEM = ANYOS

TARGETSYSTEM = database

DESTINATION

SY-SUBRC = 1003

SXPG_COMMAND_EXECUTE failed for BRCONNECT - Reason: program_start_error: For More Information, See SYS

Job cancelled after system exception ERROR_MESSAGE

******************************************************************************************************************************************

and then , I checked tcode SM59 -> TCP/IP Connection -> SAPXPG_DBDEST_DATABASE -> Test Connection -> not OK with error

******************************************************************************************************************************************

Connection Error

Error when opening an RFC connection

ERROR: timeout during allocate

LOCATION: SAP-Gateway on host dialog.fes.com.vn / sapgw02

DETAIL: no connect of TP sapxpg from host database.fes.com.vn after 20 sec

COMPONENT: SAP-Gateway

COUNTER: 193

MODULE: gwr3cpic.c

LINE: 1973

RETURN CODE: 242

SUBRC: 0

RELEASE: 701

TIME: Tue Dec 14 00:31:03 2010

VERSION: 2

******************************************************************************************************************************************

Please help me to resolve this warning

[Former Member]

Can you open another thread for this issue please.

>>DETAIL: no connect of TP sapxpg from host database.fes.com.vn after 20 sec

Please make sure you have mounted your /sapmnt/<SID>/exe on your database server

[Former Member]

Dear Nikhil

I had installed with HA Options as belows

Server B -> ASCS & Database

Server A -> CI

Server C -> DI

how to maintain these logon group in the logon pad ?

At the present, my users log on via server A and C

Please guide me

Edited by: myfriend280985 on Dec 13, 2010 10:33 AM

[Former Member]

Under SMLG tcode create logon group or groups and assign both servers to one group.

Then While configuring the SAPlogon on user side. you need to create a new item using group server selection. for more info follow open SAPlogon --> new item --> help.

Also make suer you have entry as sapms<SID> <MSserverport>/tcp under C:\WINDOWS\system32\drivers\etc

[Former Member]

Dear Sh and Su

Must I configure logon group in tcode SMLG on Central Instance or Dialog Instance ?

I try to configure on Central Instance as belows

GROUP1 central_TST_01

GROUP1 dialog_TST_02

-> Save

After configure Group Logon (GROUP1) on Central Instance. I log on Dialog Instance , I dont find GROUP1 entry in tcode SMLG

Does I need to configure this in tcode SMLG on Dialog Instance?

@shahkashyap

your post :

******************************************************************************************************************************

Then configure SMLG so as you do not have to ask end users to make any changes in logonpad. ......

............In above scenario if your server A goes down all users will connect to Server C and vice-versa

******************************************************************************************************************************

I try to shutdown Server A, and ~70 concurrent user using on server A -> disconnected and can not log on SAP system

and they make changes IP of server A to IP of Server C (manually) to log on SAP system (or create 2 entry of 2 server in logonpad). This differ with your advice ("you do not have to ask end users to make any changes in logonpad")

Can you have a solution for this ?

Sorry If i do not understand your advice

Thanks and regards

[Former Member]

Dear Friend.

once you set up the logon group you have to maintain these logon group in the logon pad.

where as if you give IP of a server in the logon pad it will dirctly connect to the respectiver server.

i will suggest you to change the settings in logon pad to use a logon group instead of an IP.

Nks

[Former Member]

Dear Sh

This is true as expected of me (because I only have 3 servers and one for the database) and I will try your method

Thanks and regards

[Former Member]

Dear Sunil

Maybe, You do not understand me, I would like to present the issue again, as follows :

I have just three server for Production model

I want to build applications (ABAP) on server A&B for share workload between them (not cluster application) and build DB instance on server C (not using cluster for database).

~ 140 concurrent user logged on SAP

For example of my desire:

I need to use distributed option:

1) Install CI on server A

2) Install DB on server B

3) Install DI on server C.

At the same time, ~70 concurrent user logged on server A and ~70 concurrent user logged on server C. If server A was be down => ~140 concurrent user logged on Server C and vice versa

Notes: With that situation above, Basis Administrator will notify (by email or by mouth ...manually ...etc) to ~70 users which are using IP of server A -> make changes IP of server A to IP of Server C to log on SAP system and => At the moment, ~140 concurrent user logged on Server C and vice versa

Question: When server A (contains CI)was be down, All users can log on on server C into SAP system and work ?

More Question: With Distributed model option, Does CI contains Message service and Enqueue service ?

=> Above, that's what i want. First, my desire is so

With my wishes, you can make recommendations for my model ?

[Former Member]

In that case you can go in for HA installation and install in following manner:

Server B -> ASCS & Database

Server A -> CI

Server C -> DI

Then configure SMLG so as you do not have to ask end users to make any changes in logonpad. For which you can refer the SMLG configuration link that I had shared earlier.

But you have to keep one thing in mind: In above scenario if your server A goes down all users will connect to Server C and vice-versa but as you are not using Cluster if server B goes down your entire SAP system is down. Because ASCS and Database are SPOF which you are not safeguarding by any cluster solution.

Thanks & Regards,

Kashyap Shah

SAP Technology Consultant

[Former Member]

Dear shahkashyap

Maybe , You do not understand me. Please you read contents below:

I have just three server for Production model

I want to build applications (ABAP) on server A&B for share workload between them (I do not know the concept of what the so called - such as: cluster application or a different concept) and build DB instance on server C (not using cluster for database).

~ 140 concurrent user logged on SAP

For example of my desire:

At the same time, ~70 concurrent user logged on server A and ~70 concurrent user logged on server B. If server A downed => ~140 concurrent user logged on Server B and vice versa

=> Above, that's what i want

With my wishes, you can make recommendations for my model ?

P/S : We do not discuss about HA here

[Former Member]

Without HA/Cluster solution you can not achieve what you want.

Thanks & Regards,

Kashyap Shah

SAP Technology Consultant

[Former Member]

>>P/S : We do not discuss about HA here

I think you are not clear about your installation what exactly you want to install SAP applications.

In simple, if some reason your server A is not working and you want your CI to be moved on server B or your server B not working and want to move applications to server A. To achive this you need to configure HA (cluster) without this it is not possible.

If you do not have HA installed/configured in you landscape then you can use distributed installation method.

Server A - CI

Server B - DB

Server C - Dialog instance (DI)

[Former Member]

Dear shahkashyap

If Server B (which contains ASCS) was down => ASCS will be down

-> Can users log on SAP system ? -> Thus, to safety, can we install a additional ASCS service on Server C ?

At that time, the following model :

A Database (+Application Server optinally)

B ASCS + Application Server

C ASCS + Application Server

Or, can we do configure cluster for ASCS ? Or simply installing a additional ASCS service on Server C for safety of ASCS service

Besides, Can you guide me to configure SMLG for load balancing after setting up completely ?

[Former Member]

The whole purpose of having cluster solution is that SPOF services keep on running.

For e.g. if server B fails which has ASCS, cluster software fails it over to server A and ASCS service keeps on running.

You need to follow the link:

https://cw.sdn.sap.com/cw/community/docupedia/tig

to understand HA, Cluster solutions, etc.

To use Red Hat Cluster Suite as a Cluster Solution you can refer following link:

http://www.redhat.com/f/pdf/ha-sap-v1-6-4.pdf

You can browse through following link for SMLG configuration:

http://help.sap.com/saphelp_nw70ehp1/helpdata/en/c4/3a64b4505211d189550000e829fbbd/content.htm

Thanks & Regards,

Kashyap Shah

[Former Member]

Dear Sunil

Thanks for your reply

As per your reply, You recommeded me to choose Distribute Model

Thus, the model will be as follows:

On server A, I will install and configure CI Instance

On server B, I will install and configure DI Instance

On server C, I will install and configure DB Instance

After setting up successful, for a reason, Server A (CI Instance) downed, concurrent users (~ 140 user) can log on server B and working normally ?

As I know, CI contains Message service and Enqueue service -> If CI downed, Message and Enqueue service did not work. With this situations, concurrent users can log on through server B (installed DI )

[Former Member]

Some basic points to highlight here:

Following are SPOF (Single Point Of Failure) components in SAP which means if any/all of this goes down your entire SAP system will be down:

1. Database

2. ASCS (which contains Message server and Enqueue Server)

So with Message server and Enqueue server being separated from Central Instance, Central Instance is as good as any other Dialog Instance. So the Central Instance term itself becomes obsolete and there is no difference between central instance and any dialog instance and so failure of any instance does not affect SAP operations if at least one of the instance is UP and running + the logon configuration is done appropriately.

You can refer Technical infrastructure guide available under installation at http://service.sap.com/instguidesnw70

The above setup (where ASCS is separated from CI) is called HA (High Availability). SAP HA solution works on top of Operating System cluster software.

So in your case to make it active-active cluster you can put SAP components as:

Server SAP Component

A Database (+Application Server optinally)

B ASCS + Application Server

C Application Server

Application Server could be CI and/or DI

Once above setup is in place to just need to define logon load balancing using SMLG transaction. In which you should create a group containing all servers and User's logon pads should be configured to logon to this group and not individual application server.

Thanks & Regards,

Kashyap Shah

SAP Technology Consultant

[Former Member]

Dear Sunil

I have just three server for Production model

I want to build applications (ABAP) on server A&B for share workload between them (I do not know the concept of what the so called - such as: cluster application or a different concept) and build DB instance on server C (not using cluster for database).

~ 140 concurrent user logged on SAP

For example of my desire:

At the same time, ~70 concurrent user logged on server A and ~70 concurrent user logged on server B. If server A downed => ~140 concurrent user logged on Server B and vice versa

=> Above, that's what i want

With my wishes, you can make recommendations for my model ?

I do not know 3rd Third Party Interfaces, can you tell me about this ?

Thanks and regards

[Former Member]

As per your reply you need to use distributed option.

1) Install DB on separate server

2) Install CI on separate serer

3) Install Dialog instance on separate server. (This can be done later, first make sure you DB and CI is up and running)

[Former Member]

Dear Sunil

With my model -> I want to build applications on server A and B for share workload between them and build DB on server C

With my wishes, you can make recommendations for my model ?

For example

CI,DB,DI which installed where on server A,B and C ?

[Former Member]

First confirm whether you are using cluster or not?

and what your system load will be?

and how many concurrent user logged on?

Any 3rd party interfaces?

[Former Member]

Dear Sunil

Yes , I want to implement as your advice. That's what I want . Maybe, i do not know about this

Besides, my desire the same as I had read Raghu's reply in this thread ->

and Brian's reply ->

As your advice, Must I choose Distribute model or HA model for my landscape in SAPinst ?

Please help me to configure as your advice.

Thanks and regards

Edited by: myfriend280985 on Dec 9, 2010 3:55 PM

[Former Member]

It depends on how your system (OS) is configured. If you have clustered servers (CI/DB) then use HA model.

If you want the DB and CI on different host then use Distribute model.

If you want install CI/DB on one host then need to use central installation option.

I think, the definition of above modules are already in installation guide.

[Former Member]

Dear Sunil

I have three server -> temporarily called A, B and C

I just want to implement cluster active-active model for Application ABAP between server A and B (Not cluster Database)

And server C, I setup Database Instance

But I do not know what to choose model (Distribute or HA) as my landscape ?

Example :

A (Appcation node 1) <-> B (Application node 2)

\ /

\ /

C (Database)

[Former Member]

As per my knowledge you can't do cluster for application server.

why can't you use the tocde SMLG load balancing for your application server, which is same as cluster. This will automatically distribute you load and if one is down user should go another app server.

[Former Member]

Not sure what exactly you are looking for? what is A, B, C?

For HA configuration you need to have 2 server same OS and version. Configure cluster software and then create cluster resources for ASCS (MS & EQ), CI (central instance, DB (database). You need to follow the HA model to complete the installation.

Then install dialog instance on separate hosts if you require.