Activation of HSR in MDC architecture

[GioS]

Hi Expert,

I'm planning my technical architecture for an ECC and BW landscape on HANA.

I would like to use only 2 HANA Appliance and I’m planning to use the following MDC configuration:

HANA Appliance 1 :

• ECC (Prod)+ BW (prod) -> 1 Hana system + 2 Tenant DB

HANA Appliance 2 :

• ECC (Prod standby)+ BW (prod standby) + BW/ECC(DEV, Test) -> 1 Hana system + 6 Tenant DB

I would like to know if I can activate HSR between the 2 appliance. In the “SAP HANA Tenant Databases - Operations Guide” I found the following:

The usual SAP HANA system replication principles apply for tenant database systems.

Before you begin preparing a replication strategy for an SAP HANA system, you should be aware of the following important points.

●SAP HANA systems can only be replicated as the whole system. This means that the system database and all tenant databases are part of the system replication. A takeover can only be performed as a whole system. A takeover on the level of a single tenant database is not possible.

Based on what indicated above I should not be able to replicate the data form Appliance 2 to Appliance 1. Is this correct? Is it possible to define in the second HANA Appliance 2 HANA System like indicated below:

HANA Appliance 1 :

• ECC (Prod)+ BW (prod) -> 1 Hana system + 2 Tenant DB

HANA Appliance 2 :

• ECC (Prod standby)+ BW (prod standby) -> 1 Hana system + 2 Tenant DB
• BW/ECC(DEV, Test) -> 1 Hana system + 4 Tenant DB

In this case I should be able to activate HSR only for PRD systems.

Thanks

G.S.

[dennispadia]

Hello,

In order to design HANA architecture, you need to keep below points in mind -

1. All environments (DEV, TEST, PROD) cannot be installed in a single HANA System i.e. 1 HANA Appliance > 1 HANA System (SYSTEMDB) > 6 Tenant Database.

Technically you can create as many tenant(s) as you want in a HANA System. But the challenge with MDC is that when you apply patches to multi-tenant environment, you're applying patches to all the systems simultaneously. So once you patched your HANA System through MDC, you have patched all environment in HANA System - all at the same time, which is a huge disadvantage. This is why you need to separate non-production from Production (standby).

2. Also in order to configure HANA System Replication, you need to have same configuration of Primary Production HANA System (SYSTEMDB + 2 TENANTDB) and Secondary Production HANA System (SYSTEMDB + 2 TENANTDB). In order to achieve this, you anyhow need to separate your Production HANA System from non-production HANA System and this can be achieved using MCOS installation

3. As highlighted in point 1, patching multi-tenant environment will apply patches to all the systems (if you are placing them in a single HANA system). So you need to separate your HANA database based on the environment as well. So recommended method is to install DEV and TEST as separate HANA System (MCOS Installation).

4. As you have not mentioned that the appliance will have virtualization layer, I assume that you are going to install everything on top of Physical server. As highlighted in Point 1, 2 and 3 your architecture will look like this based on your restriction to use only 2 physical appliance.

Appliance 1 - Production > 1 SYSTEMDB + 2 TENANT DB (ECC/BW)

Appliance 2 - Production(Standby) + Non Production (DEV) + Non-Production (Test) > Each environment will be installed separately on same appliance with different SID using MDC deployment option. So appliance 2 will have 9 SID's (3 SYSTEMDBs + 6 TENANTDBs)

5. I wouldn't go with above configuration as my Appliance 2 have 9 databases running on top of single OS sharing CPU resources. Instead I would suggest to have virtualization software on top of physical server so that I can create three VMs (Prod-standby, dev, test) for each environment and CPU utilization can be isolated. Also having separate VMs for each environment will help in future for OS upgrade.

Regards,

Dennis