Why splitting off the ASCS from PAS?

[former_member186845]

As you might know, currently when you will perform an installation of a fresh SAP system based on SAP NetWeaver 7.0x and higher, there is an instance for ASCS. It was separated from PAS for all the fresh installations.

But why SAP did that?

Because it is very crucial to ensure the availability of the Message Server and the Enqueue Replication Server. This way you will have one dedicated instance to perform the failover. Apart from High Availability, SAP recommends and/or wants to enable a setup where all systems have the same types of instances. For this reason and also to make High Availability enabling a bit easier, the split off functionality has been delivered.

But if you have installed your SAP System a long time ago and your ASCS is into the PAS, you can split them into 2 instances. For systems based on SAP NetWeaver 7.1 or higher, it is possible to use the latest version of SWPM (For further reference, please check SAP note #1680045).



I used as example the option to split off a SAP NetWeaver 7.3 EHP 1 with Oracle. But the option is available for every system and database combination present in the SWPM for NW 7.1 and higher.

But if you have a system based on SAP NetWeaver 7.0x, this option is not available in the 70SWPM, The only way to do that would be running a system copy of the system. Then during the target system installation, you would be able to install the new system with separated ASCS from PAS .

For further information regarding this subject, you can check the Installation Guide for SAP NetWeaver 7.1 and higher. Check the section 2.5 Central Services Instance for ABAP Separate from Existing Primary Application Server Instance of an Upgraded System for further information regarding the subject pointed in this post.

Also check the section 7.6 Splitting Off a Central Services Instance for ABAP from an Existing Primary Application Server Instance to know how to run the split.

[former_member218805]

Nice explanation! Thanks Henrique!

[Former Member]

shouldn't it read

     "It was separeted from the PAS for all the fresh installations."

instead of

     "It was separeted from the ASCS for all the fresh installations."?

regards

Peter

[Former Member]

I would say :

"It was separeted from the Central Instance for all the fresh installations."

From my understanding the CI was split between the ASCS and the PAS.

Regards,

Olivier

[Former Member]

Hello Henrique,

Good Day!

This is a very good information for us.

Thank you for sharing this discussion.

We are planning to start the Splitting ASCS from PAS.

Best Regards,

Prabhu Reddy.

[Former Member]

Hi Henrique,

I have question here that in the guide, it says that we should be at SAP NW 7.3 or higher to be able to split ASCS. Does it mean that all the existing Releases like NW 7.02, ECC 6.0, SCM 7.0, Solution Manager 7.1, CE 7.3, GRC 5.3 need to be upgraded to latest and then perform the ASCS Splitting.

Please suggest.

Best Regards,

Prabhu Reddy.

[former_member186845]

Hi Prabhu,

Please note that for systems based on SAP NetWeaver 7.0x, as described in the post, it can only be split by running a system copy:

"But if you have a system based on SAP NetWeaver 7.0x, this option is not available in the 70SWPM, The only way to do that would be running a system copy of the system. Then during the target system installation, you would be able to install the new system with sepated ASCS from PAS."

Regards,
Henrique

[Former Member]

Hi Henrique,

Thank you for the answer.

Best Regards,

Prabhu Reddy.

[Former Member]

Hi Henrique,

I have another question, How do we perform the SCS split from CI/PAS for J2EE (JAVA) systems only? Is it same procedure as ASCS split.

We are also planning to split SCS from EP 731. Please suggest.

Best Regards,

Prabhu Reddy.

[Former Member]

Hi Henrique,

I have another question, How do we perform the SCS split from CI/PAS for J2EE (JAVA) systems only? Is it same procedure as ASCS split.

We are also planning to split SCS from EP 731.

We do have Composition Environment (CE-731) and are planning to split SCS. Can SCS split from CE server?

Please suggest.

Best Regards,

Prabhu Reddy.

[Former Member]

An ASCS (an ABAP SCS instance) consist of two processes originally belonging to the ABAP Central Instance (msg_server - a separate process and the functionality of the ENQ-workprocess of the ABAP-Server). The ASCS Split deletes those two from the Central Instance (DVEBMGS) configuration and puts them into an own (ASCS) instance.

The message server and enqueue server processes of a SAP J2EE server were configured as an own instance (SCS-Instance) since the first delivery of the SAP J2EE server.

Therefore there is no need to separate them from the SAP J2EE instance.

regards

Peter

[former_member186845]

Perfect explanation Peter! Thank you for adding this information.

Regards,
Henrique

[Former Member]

Quick question Henrique.

I referred the current SWPM procedure for 7.1 and higher on splitting ASCS and PAS.  I have a question here please. The first point in the Procedure has 2 items -1) Choose an instance number for the ASCS instance to be created.  2) Note that the message server port is not changed during the split.  I am wondering how can this be. I thought DVEBMGSXX will split into ASCSXX and DXX.  If point 1 holds good that means I can choose a port of my convenience and if point 2 is true, then that means I cant choose ASCS port of my liking. Both cant co-exist or am i missing something here. I basically want to have current port( Central CI port which is common for Message,Enqueue and Dispatcher) to be used by PAS after split and this is not possible if point 2 above holds good. We have several interfaces that are pointed to this port and we don't want to end up adapting all RFC interfaces and gateway ports etc. We don't have HA so SPOF is not an issue here and we have 2 application servers that cater to transaction user loads and batch schedules.

Any thoughs here please

Regards
Kalyan

[Former Member]

well, the port of the message server defaults in the standard installation to 36$(NR)

Fact is that all other ports (sapdp, sapgw, sapdpXXs and sapgwXXs) are bound to the number of the instance and can't really be changed.

whereas sapdp, sapgw, sapdpXXs and sapgwXXs ports need to be unique on a computer, the message server port sapms$(SID) normally needs to be unique in a company (to avoid double portnumber is the services). Therefore the portnumber of the message server can be choosen freely in the free port range of your company.

It is just it's installation default value which indicates that it is depending on the system number - but it is not!

kind regards

Peter

[Former Member]

Thanks Peter. Just a follow up question.

New installations default to PAS to use 00 and ASCS to use 01.  I know we can change it however I never did. I want to know if its okay to interchange this(PAS to 01 and viceversa). Reason why i ask is we don't want to end up changing RFC interaces to point to a new port after the split and want to continue the same way. Just wondering as there must be a reason why SAP installations default to these ports or are these just picked up just because they are free. I dont know any internal aspects impacting the split so just trying to be cautious here.

Regards

Kalyan

[former_member186845]

Hello Kalyan,

As Peter mentioned you can freely choose the port according to your business needs.

The number provided by the installer is just a suggestion, this is not a rule. Therefore you can invert the instance numbers if you wish.

Regsards,
Henrique

[Former Member]

well, splitting the PAS (formerly know as CI) up to an ABAP only instance and an ASCS instance was primarily done because of this reasons:

1. HA configurations where using this instance setup sine 7.0. The ASCS instance consists of the only single point of failure parts of the ABAP server system. This instance is taken under control of HA monitoring software (on Windows: Windows Failover clusters)
2. Some alternative HA-like configurations like VMware FT had a lack of performance (supporting only one CPU in their first versions), therefore they were also interested to separate the single point of failure to the light weight ASCS instance in order to put this instance under control of VMware FT.
3. with one of the next kernel versions coming out (7.41 or 7.42??) there will be the support of a rolling kernel upgrade. This functionality will allow you to upgrade the kernel of the ABAP server while the system stays under production. It is restarting instance after instance without downtime of the complete system. A prerequisit for this functionality is an ASCS configuration.

When running an ASCS configuration it is important to have the right RFC configurations in place in order to allow the system continue to run, when the primary application server is down or just restarted. RFC-Clients need to have a Logon Group based connection configuration in order to perform this task. In this case only the port number of the message server (sapmsSID) needs to stay - there is no influence of the system number of the ASCS instance on the port used to connect to the message server.

There is a good knowledbase article which describes the details about this for HA configurations. But - there is no difference to Standalone ASCS instance configurations.

regards

Peter

[christoph_ostrop]

Hi,

nice blog,

one question:

we are on NW-7.40 (without any SR) NW-7.40 SP04 and ECC-617 SP02

we want to splitt ASCS from the already installed PAS

we could find the download to SWPM 1.0 SP07 PL-6 (SWPM10SP07_6-20009708.SAR) in the swdc.

but starting this SWPM-Version, there is no option for NW-7.40 (without SR) ????

what tool do i need to separate an ASCS instance from an NW-7.40 ERP

Chris

[former_member186845]

Hi Chris,

In your case, you mentioned your system is SAP ERP 6.07. Therefore, you should use the option under "SAP Business Suite 7i 2013 > EHP 7 FOR SAP ERP 6.0 ABAP SR1 > <database> > Additional SAP System Instances ".

Even your system is not in the SR1, you can use this option to separate the ASCS from PAS.

Regards,
Henrique

[Former Member]

Hello Henrique

I am looking into splitting ASCS from SOLMAN 7.1 SPS 11. As per your explanation above, I have to go through "System Copy" in order to do the split. Do you happen to have an example? Are the splitting steps documented somewhere? I believe I have to this manually.

Thanks.

[former_member186845]

Hello Nader,

Solution Manager 7.1 is based on SAP NetWeaver 7.02. Therefore, you should use the 70SWPM to perform the system copy. During the target system installation, you will noticed the options to install has PAS and ASCS installation steps separately. There is nothing else to do.

For systems based on SAP NetWeaver 7.1 or higher, the SWPM tool has an option to split it automatically. But, this cannot be done for systems based on SAP NetWeaver 7.0x.

Thanks and regards,
Henrique    

[Former Member]

Hi Henrique

Thanks for your quick reply. I tried to follow the process but no success so far. Here are the details:

• I am running SAP on AIX/Oracle 11.2.0.3
• I used 70SWPM10SP08_3-20009697.sar
• I am testing this procedure of the sandbox, distributed installation

• First, during the export, SWPM was looking for "/oracle/client/12x/instantclient/ojdbc14.jar", which does not exist since we are running Oracle 11. I create a softlik to bypass this step.
• I started the target system installation on the same host, and the process takes long time to check the permission on every single file on the existing instance.
• When the file permission step is completed, the process hangs and does not move at all. I repeated that few times, but still did not work.

Did I miss something?!

[former_member186845]

Hello Nader,

In fact, the issue you are facing is not related to ASCS/PAS split, but with system copy.
It would be necessary to analyze the log files to check this issue. Here is not the best place to troubleshoot your issue.

Can you please open an SCN Tread about it?

Thanks and regards,
Henrique   

[Former Member]

Thanks Henrique. It turned out to be an issue with 70SWPM10SP08_3-20009697; I downloaded 70SWPM10SP08_4-20009697 and it worked fine for the installation.

Now that I did the export and installed ASCS; when I try to go through System copy --> Oracle --> Target System installation --> Distributed System --> Central Instance, the process is looking for installation CD and not accepting the export. Any hint for that?

[symon_braunbaer]

Hi Henrique,

I have noticed, that with SWPM versions since about the beginning of 2014, no separate ASCS instance is installed by default. Can you kindly comment on this ?

Thanks!

[former_member186845]

Hi Symon,

Are you sure about it? This is an example of options from the latest version of SWPM tool. As you can see, the ASCS instance step is separated from Primary Application Server instance.

Why do you say no separate ASCS instance is not installed by default?

Regards,
Henrique

[symon_braunbaer]

I am sorry, but I cannot prove it 😞 Systems which I have been installing in the end of 2013 had ASCS and CI, then starting with 70SWPM in January or February, only CI was installed. I saw now, that systems built later in 2014 are having the ASCS as well.

I tried to find that SWPM which would be installing only CI, but the servers have been cleaned up long time ago and recently I have also been cleaning my laptop's drive, as it got completely full and I might have deleted this SWPM version as well...

[former_member214380]

Hi there,

thanks for your contribution. I do have question on that: Currently I am doing a NetWeaver 7.31 Release system copy using the SWPM10SP08. Unfortunately it looks like we are being forced to split the ASCS while this procedure. Due to our system landscape we would rather not do this split while copying the system.

Is there any known way to prevent this split?

Regards and thanks in advance!

Daniel

[Former Member]

Hi Henrique,

I am trying to install ECC6.0 EHP7 (NW 7.4), we don't want to split message server and PAS. Is there any way to do it.

Why we don't want to split is in our landscape all the systems having single instance no, if we change this this will differ to existing landscape architecture.

Thank you,

Raam.

[former_member214380]

Hi Raam,

are you installing the system from scratch or is it a system copy as it was in my case? If it is the latter, you can choose the option "Refresh" from the SWPM. This will take over the existing system and no changes to the Instance will be made.

Btw. This is also the solution to my question I have asked above 😉

Regards

Daniel

[Former Member]

Hi Daniel,

I am Installing from the Scratch (New Build).

Thank you,

Raam.

[former_member214380]

In this case I am sorry since I cant be of any help. But I am rather interested on the solution - if there is any.

[Former Member]

Why we don't want to split is in our landscape all the systems having single instance no, if we change this this will differ to existing landscape architecture.

there is no technical need for this kind of architecture!

Lack of RKS (Rolling Kernel Switch) support of the CI setup is the main reason why going for the separate ASCS instance configuration.

Keeping installation configurations uniform (upgraded systems vs newly installed systems) eases support and minimizes upgrade problems in the future caused by possible configuration combinations.

If there is currently a possibility  to still install a system as CI, it is intended for installation additional components (for example dialog instances) to older systems and should not be used for complete new installations.

best regards

Peter

[isaias_freitas]

Hello Peter,

The enqueue process is moved to the ASCS.

The standalone enqueue would have a better performance than a work process of type enqueue.

In addition, having the ASCS is required if you want to have High Availability (the ASCS can be clustered; you can then have an enqueue replication instance - ERS, so the locks are not list in case the ASCS fails over).

Finally, as of SAP NetWever 7.4, the ASCS is mandatory even for non-HA installations (although it would still be technically possible to have a "classic CI" instead of an ASCS).

Best regards,

Isaías

[former_member206857]

I'm about to try it, I see no where does it say you need to stop SAP server or the SAP services before launching SWPM? Or does it not to be stopped? Or can they all run and the SWPM tool stop it, make the changes and restart them?

Guess only 1 way to find out....

[former_member186845]

Hello Joshua,

SWPM will ask you to stop the system, in case it is not stopped already.

Therefore, yes, the system must be stopped during the process.

Regards,
Henrique    

[former_member182505]

Hello Henrique

I have requirement to split ASCS instance on SAP NetWeaver 7.0x, without doing system copy, Could you  please help me any possibility , i checked all the related links and sap notes, which talked about not possible,

http://scn.sap.com/thread/3459662

https://scn.sap.com/thread/3464584

http://scn.sap.com/community/netweaver-administrator/blog/2013/12/04/why-splitting-off-the-ascs-from...

2119669 - How to split the ASCS from Primary Application Server (PAS)

2073500 - FAQ: Splitting off ASCS from PAS

Is there any possibility to do manually, I understand SAP does not recommend , but we can not do it with system copy,

How can we do manually and what are all the steps ,

Thanks for the help

Sadiq

[former_member206857]

No need for a system copy, I just performed one yesterday on my sandbox. Took 6 minutes. Leave the instance running, SWPM will restart it and then done. such a very simple thing.

[former_member182505]

Hello Joshua

Thank you so much for quick reply,

My question is to do for SAP NetWeaver 7.0x, system for that there is not option in SWPM to split,

as per note 2073500 - FAQ: Splitting off ASCS from PAS

4.  How can the ASCS be splitted off from and existing PAS in systems based on SAP NetWeaver 7.0x?

Differently of systems based on SAP NetWeaver 7.1 and higher, there is no option in SWPM to split off ASCS from PAS. This is not possible to be done automatically. Also manually modify files is not supported.

The solution for systems based on SAP NetWeaver 7.0x is to perform a system copy. Then during the target system installation it will be possible to install the new system with separated ASCS and PAS.

Thanks

Sadiq

[former_member186845]

Hello Sadiq,

In fact, there is no supported manual procedure so far that can be done to split the dual-stack system based on SAP NetWeaver 7.0x. The only way is running the system copy.

I also would like to remember that I am from SAP and I am also the responsible for SAP KBA 2073500 that you are referring to.

Regards,

Henrique

[former_member206857]

I'm trying to think why SAP wouldn't allow 7.0 to split? I have no clue why? Kernel version support maybe??Simply the SWPM Tool for 7.0 doesn't have the option.

I can;t think off the top of my head why technically they don't use the tool..nothing coming to mind.

[former_member182505]

Hi Henrique and Joshua

Thanks again for quick reply,

@Henriuqe :- is there any possibility on coming days are after few weeks, because we have  running production systems and we can not do system copy and customer will also not be agree for that, we have only option to do with SWPM on 7.0x systems,

I read all the documents and note provided by you but its not helping on my case

@Joshua;- thanks and please share if you get anything new,

Thanks

Sadiq

[former_member186845]

Hello Joshua,

Systems based on SAP NetWeaver 7.0x have a different technology than SAP NetWeaver 7.1 or higher. This is why they have different SWPM versions.

However, I cannot tell you with 100% why it cannot be done automatically for systes based on SAP NW 7.0x.

Regards,
Henrique

[former_member186845]

Hello Joshua,

I do not have any information if such procedure will be developed for SAP NW 7.0x.

Regards,
Henrique

[former_member182505]

Hello Henrique

Thanks Again,

So you do not recommend to do it manually ? and Why?

Any impact ?

Any future problem?

If i would like to do manually what changes need to be made?

Thanks

Sadiq

[former_member186845]

Hello Sadiq,

As mentioned before, manual modifications are not supported by SAP. There are no manual steps for that. Additionally, there is no way to analyze possible future issues, once there are no manual steps for that.

Any manual modification will not be supported by SAP. It can only be split via System Copy procedure (for SAP NW 7.0x).

Regards,

Henrique