An interview with Carsten Stolzenbach. Certified SAP HANA Consultant

In 2012, Basis Consulting did their first HANA project for Zalaris. Now they are running SAP BW, CRM and ERP on HANA. I caught up with Carsten to hear about the latest SAP Business suite on HANA project. 
 
Interviewer:
Which approach did you choose for the migration to HANA and why (upgrade->migrate, migrate->upgrade, new landscape, etc)?Carsten

Carsten:

Both a system upgrade and a database migration of a 2+ TB system needs a lot of downtime and normally would have to be performed in two steps. Last year SAP introduced a new feature for the Software Update Manager (SUM) which combines the upgrade of the SAP system with the migration to HANA. This feature is called “Database Migration Option” (DMO), (ref Picture3). Using this feature gave us a couple of advantages: We could perform the system upgrade and the database migration in one downtime weekend, and Zalaris only had to run their tests once. Afterwards we still had the old database available, in case we had to roll back after test phase.

Interviewer:
Which steps are necessary to perform before the migration phase?


Carsten:

In fact the migration from the legacy database to HANA is no big deal, and works as any heterogenous system copy known in the SAP world. The real challenges in this project were the prerequisites for the migration. First of all the ERP system had to be upgraded to Ehp7 – a step that always involves a lot of resources on the customer side. On the other hand, we had to define a concept in order to integrate the new HANA systems in our existing data center infrastructure. Here we had a close cooperation (and a lot of discussions) with SAP in Walldorf. They included us in their HANA TDI (Tailored Datacenter Integration) program which opens up for running HANA systems on enterprise storage systems instead of the former appliance approach. In addition we had to decide for a HA/DR setup fulfilling both Zalaris and Basis Consulting’s operational requirements. In the end I would say that 50% of the project time was used for planning, discussing and deciding on the way to go. In my opinion it was time well spent, as a wrong decision could have become expensive for both Zalaris  and Basis Consulting.
(About Basis Consulting’s HANA TDI: https://sites.google.com/a/basis-consulting.com/sap-hana-tdi/)

Interviewer:
Did you use a sandbox before migrating the development system? If yes, what experience did you gather from the sandbox environment?

Carsten:
In fact we used two sandbox systems for testing in advance. The first one was used for a pure upgrade to EHP 7 without migration to HANA. This system was used by Zalaris in order to test EHP 7 as much as possible before upgrading the actual production landscape. On another sandbox system we performed a single run of the combined upgrade/migration with DMO. This was a technical-only test to get used to the new tool, find out the differences to a plain upgrade and to get an idea on timing (esp. for downtime).

Interviewer:
Two sandboxes in addition to standard landscape must require a lot of HANA hardware?

Carsten:
Not really. In Basis Consulting, we have been running HANA test systems on our standard hardware for a long time. It’s not officially supported by SAP, but it’s perfect for non critical HANA systems with few users. We can reuse our standard platform in the hosting center and the cost for HW is less. HANA is a database supporting Linux only, and Linux is also Basis Consulting’s standard platform. A good match for Basis Consulting.

Interviewer:
Did Zalaris have to test a lot before HANA migration?

Carsten:
The majority of tests were related to the upgrade from EHP 5 to EHP 7. The additional tests related to HANA migration added appr. another 10% of test time.

Interviewer:
Normally, ERP ECC is a customer critical application. What options to you have for HA and DR for a HANA database? In your case, which option did you choose for HA/DR and why?

Carsten:
SAP offers a couple of options to run HANA in a HA and/or DR scenario. Due to the appliance approach this can involve a lot of extra H/W needed for failover situations. For a scenario that includes both HA and DR you have to triple the H/W needed – a costly approach. In the end we decided for a DR only scenario with SAP’s HANA System Replication functionality. In this approach each HANA system is represented by a second HANA system located at a secondary site. The DR HANA system is continuously updated with all changes performed on the primary system and tables already loaded to memory at any time. Thus a failover to the second system can be performed within a couple of minutes without having to wait for the DR system to start up.

Interviewer:
HANA is an in-memory database. How did you know how much memory that was needed for HANA?

Carsten:
SAP offers a report that can be run on the SAP system before migration. This report gives an indication on the sizing needed for HANA. In the end the sizes calculated by the report came quite near to the memory actually used on HANA.

Interviewer:
What extra benefits did the Zalaris see when changing the database to HANA (compared to a normal database with ERP)

Carsten:
To say it open: Moving an ERP system to HANA does not give the same “loosen the handbrake” experience as it gives for BI systems. Zalaris reported that everything seems to run “a little or a bit faster” than before. Dialog response time has gone down by 20-30% after the move to HANA, but this has to be taken with a grain of salt as the migration was performed right before summer holiday season. We will have to monitor the system behavior when there is “real” system load after summer holidays. I would expect extra performance benefits in the future when SAP moves heavy application calculations from SAP instances down to HANA database. I think there still is a lot of potential for performance gains when SAP continues on developing for Business Suite on HANA systems.

Interviewer:
Is there any new stuff for the end user after the database is moved to HANA?

Carsten:
Zalaris approach was to run a pure technical upgrade in order to be able to move to HANA. New functionality made available by EHP 7 and/or HANA might be enabled at a later point of time.

Interviewer:
Thanks for taking time to explain the HANA project, Carsten. Great job and congratulations with another successful migration.

About Basis Consulting:
Basis Consulting is specialists in SAP and their hosting center is specially designed for SAP systems. They are certified as SAP Advanced hosting partner and SAP certified in SAP HANA Operation Services
www.basis-consulting.com

About Zalaris:
Zalaris excels in delivering comprehensive HR and payroll services across Northern Europe, the Baltics and Poland. 
Zalaris serve more than 140,000 employees each month, from across multiple industries and with many of the region’s most reputable employers.

www.zalaris.com 

Interviewer: Svein Kolden, BC employee