SAP HA Active/Active architecture

[Former Member]

Dear All,

We are trying to implement  SAP HA Active/Active.

The application servers will have HA on Active/Active and the database servers are going to be active/passive using Oracle Dataguard.

As per the proposal put forward by our implementors, we need 3 application nodes or servers.

Out of the 3 nodes, only 1 node will have an active CI.

The other components will be active on all the 3 nodes.

However the CI component when it fails, it must automatically failover to the next node (N+1).

So this must be managed via the HACMP from the OS side for clustering.

Now we have heard from people that usually the CI component is setup on the passive node of the database server which is managed by the HACMP.

So the app nodes are running in parallel using load balancer and the CI will run on the passive node of the DB server which is managed by the HACMP.

How true is this? What is the proper architecture please?

Thanks and Regards,

Augustine

[former_member188883 · Accepted solution]

Hi Augustine,

As per SAP guidelines, following are the Single Points of Failure within an HA environment

1) Database service

2) Message service 

3) Enqueue service. 

Rest other components are not considered as Single Points of Failure in an HA environment and hence they are configured locally without HA.

Ideally for an Active - Active HA setup, customers follow the below setup

1) Node 1 : Database + CI instance + ERS

2) Node 2: ASCS + Dialog instance

When Node 1 fails , DB instance moves to Node 2

When Node 2 failes, ASCS instance moves to Node 1

ASCS contains Message services + Enqueue services

ERS is a enqueue replication server

In your setup

==========

Oracle Data guard cannot be used for HA setup. It is meant for DR configuration and log shipping.

You need to re-check and align your HA setup which suits best for your organization.

Hope this helps.

Regards,

Deepak Kori

[Former Member · Accepted solution]

Dear Deepak,

Thanks for your inputs. They are helpful.

However, let me just tell you that Oracle Data Guard being used for HA is an approved configuration by SAP for SAP HA. Oracle DataGuard can also be used for DR as well as for HA (Active/Passive) setup. This is completely accepted by SAP as one of the standard configurations for Active/Passive.

However based on your inputs it seems to me that the DB server nodes can be made to host the CI as well. The passive node of the DB server will host the CI so that the passive DB server is being made use of and in case of failure the CI would move to the active DB node thus sharing the load with the DB on the active node. Looks like this is a valid configuration.

Can you please do me a favor and let me know of any SAP notes or articles that describe such High Availability architectures for SAP?

Thanks a lot

Regards,

Augustine

[former_member188883 · Accepted solution]

Hi Augustine,

I could find some docs from SDN , Please refer below

http://scn.sap.com/docs/DOC-25454

http://scn.sap.com/docs/DOC-26718

http://scn.sap.com/docs/DOC-7848

Hope this helps.

Regards,

Deepak Kori

[americo_goncalvesqualho · Accepted solution]

Hi Augustine,

The straight-forward point is:   you don't need to failover (move) CI!

Just because CI is no a SPOF.

Regards,

Americo.

[stefan_koehler · Accepted solution]

Hi all,

@Deepak

> Oracle Data guard cannot be used for HA setup. It is meant for DR configuration and log shipping.

Oh really and why is Oracle Data Guard called as a "high availability solution"? (Source: Oracle Data Guard with Oracle Database 11g Release 2)

Data Guard is the data protection and availability solution for Oracle Database.
...
It can address both High Availability and Disaster Recovery requirements and is the ideal complement to Oracle Real Application Clusters.

... and have you ever heard of observer in a DG environment for FSFO?

@Augustine

Well you have not provided enough information and it is also pretty hard to do architecture work on a forum platform. Do you plan to run a distributed SAP system landscape and run the database in a separate PowerHA cluster as well or do you plan to use FSFO (with observer) for the database layer? Are the database servers already included in the 3-node SAP infrastructure?

By the way there is nothing like a SAP CI anymore, if you are using a SAP SCS (with our without ERS). There is a plugin for PowerHA to manage all of this stuff more easily "Planning for Smart Assist for SAP Netweaver".

Regards

Stefan

[Former Member]

Dear Augustine Amalesh,

HA can be implement with various structure dependent upon client requirement & available resources. 

Similar kind of sap landscape as offered to you for A+A HA is working at one of my client side smoothly.

The Proposal, 

" 3 application nodes or servers.

Out of the 3 nodes, only 1 node will have an active CI.

The other components will be active on all the 3 nodes.

However the CI component when it fails, it must automatically failover to the next node (N+1).

So this must be managed via the HACMP from the OS side for clustering. "

is a stable method & ideal to follow.

Kind rgds,

Ashwin Mane