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Managing hostname for SAP Disaster recovery scenario

Jan 04 at 09:09 AM

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Former Member

Dear Experts,

We are in the process of setting up DR for SAP systems installed on SAP ASE. We have decided to Sybase Replication server to achieve DR for the database layer but we still have some open questions w.r.t application layer namely:

1. How can we install the application layer in a way (I guess virtual hostname) so that the end user does not need to adjust anything in their logon pad or browser after a takeover by the standby site? In our case, the SAP system on the primary site is installed on a cluster with ASCS and DB installed on the virtual host and PAS and AAS on each of two different hosts with the physical hostname.

2. How can we minimize the need for adjusting any RFCs or interfaces after a takevover by the standy site? CNAME/A-record?

The DR will be setup on Microsoft Azure.

Thanks and Regards

Joyee

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Former Member Feb 09 at 06:14 AM
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Hello Joyee,

If you are going to do the storage base replication then the hostname will remain same however if you are going to configure the DB level replication then the hostname must be different because there will be conflict in your landscape between Primary and DR system due to same hostname.

with reference to your another question regarding the user access, you can set the alias in OS host file for the primary Hostname so there will not be any change for accessing the DR-SAP system or you can use DNS Server. So one the DR is activated then the DNS server will route all the primary traffic to DR server.

you can also consider below information so this will help you to decide a proper plan for setting up the DR for SAP Systems

http://expertisenpuru.com/disaster-recovery-rpo-rto/

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Former Member Jan 04 at 09:37 AM
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Dear Joyee

Here is official documentation how to use Azure Site Recovery https://docs.microsoft.com/en-us/azure/site-recovery/site-recovery-sap . There you will find a link to a white paper http://aka.ms/asr-sap

You should keep your host names the same (for application servers and cluster virtual host names), then you do not have to change anything in SAP configuration.

Are you using Microsoft Failover Cluster for SAP ASCS/SCS instance?

Thanks

Goran

SAP on Azure Support

LinkedIn: https://www.linkedin.com/in/gorancondric/

Twitter: https://twitter.com/GoranCondri

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Former Member Jan 04 at 11:31 AM
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Hi Joeyee

I didn’t get your point when you say you have 2-tier. 2-tier means all components need for SAP system (DB, ASCS and application sever) are on ONE host.

If you have Microsoft cluster, then it is automatically distributed e.g. you have more then one host.

Can you comment this?

Thanks

Goran

LinkedIn: https://www.linkedin.com/in/gorancondric/

Twitter: https://twitter.com/GoranCondric

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Former Member

Hello Goran,

When I say 2 tier I mean that database and application layer are still residing on the same host. There are 2 hosts ex. host1 & host 2. host 1 has the primary application server and host2 has the additional application server. DB and ASCS are installed on the virtual host which are active on host 1. In case of a failure, both DB and ASCS would failover to host2. Hope this clarifies.

Regards

Joyee

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Former Member

Hi Joyee

Let me try to summarize. I guess:

-you have host1 and host2.

-These 2 hosts are Windows Failover cluster machines, which you use to clustered ASCS instance and DB.

-And you installed locally on host1 primary application server and on host2 secondary application server?

Is that correct?

Best

Goran

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Former Member

Hello Goran,

Yes, your understanding is correct.

Thanks

Joyee

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Former Member
Former Member

OK then you have 3-tier setting.

If I correctly understood you, your primary site is on-premises, and your DR site is Azure?

What do you use in on-premises, physical, Virtual environment (which one)?

Do you use share disks for ASCS clustering?

And how is you Sybase ASE clustered, e.g. do you also use shared disks for clustered ASE?

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Former Member

Hello Goran,

Thanks for your help so far. To answer your questions:

On premise is Virtual - Vmware.

Yes, shared disks are used for clustering both ASCS and DB.

Thanks

Joyee

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Former Member Jan 04 at 10:08 AM
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Dear Goran,

Thanks for this document. To answer your question, yes, Microsoft Failover Cluster is used for SAP ASCS/SCS instance on the primary site on-premise.

Regards

Joyee

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Former Member Jan 04 at 10:16 AM
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Dear Goran,

Going through the document I realized that ASR is really useful if we have a 3 tier installation but this is not true for our case. The on-premise systems are 2-tier installations with ASCS and DB installed on the virtual host and 2 application servers installed on each of the 2 physical hosts. The installation is not distributed, i.e there is no separate DB server.

Thanks

Joyee

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