DMO and SAP HANA log mode considerations

[Boris_Rubarth]

You are working on a migration scenario to SAP HANA database using Software Update Manager (SUM) with its Database Migration Option (DMO). You wonder which SAP HANA log mode the tool is using during the migration.

The available log modes of SAP HANA database are explained in the documentation, for example using the following link https://help.sap.com/viewer/6b94445c94ae495c83a19646e7c3fd56/2.0.05/en-US/c486a0a3bb571014ab46c06332.... Relevant statements are:

• SAP HANA can run either in log mode normal or overwrite.


• After installation, SAP HANA temporarily runs in log mode overwrite.


• Log mode normal is recommended to provide support for point-in-time recovery.

New: with SUM 2.0 SP 14 (and higher), SUM will set the log mode to overwrite before the migration happens. At the end of the DMO procedure, SUM will set the mode to normal. You will then create the (first) backup for the SAP HANA database, as listed in section Follow-Up Activities of the DMO guide:
https://help.sap.com/docs/SLTOOLSET/7d57e56e12104cc68bce7646cd9f4cbf/49ecdd5aaec7494386a5af08d7946da...

This is now aligned with the behavior of Software Provisioning Manager (SWPM), which asks you to create a full database backup as well (see https://help.sap.com/viewer/3741bfe0345f4892ae190ee7cfc53d4c/CURRENT_VERSION_SWPM20/en-US/b1d3cf2bcb...).

The previous behavior of the tool was different. Up to SUM 2.0 SP 13, when you started the DMO run, SUM didn’t change the log mode. If there was no database backup taken for SAP HANA, the database has treated this as mode overwrite. At the end of the DMO run, you follow the SUM recommendations and created a full backup. After this first backup, the SAP HANA database switched to normal mode.

Boris Rubarth, Product Management SAP SE

[sudip_saha1]

Hi Boris,

Nice blog with lot of information. I follow all your blogs. I have one question, we are going to migrate our ECC6.0 EHP8 Oracle database to HANA Database with support pack upgrade. As well as we are moving our ASCS and PAS to new host because our existing host is has old Linux SLES 12 OS version. We will be using SUM DMO to Convert Oracle to HANA + SAP Upgrade. We will be using Downtime optimize option because our DB is 25TB+, however when I choose downtime optimize option shown below I don't see the system move option which will migrate our old PAS to new PAS host.

 

 

For ASCS move to new host, we need to select "I want the ASCS instance move" like in below screenshot, right?

 

 

Thank you.

[Boris_Rubarth]

Hi Sudip

thanks for asking.
Please check the information provided in the SAP Notes for DMO and downtime-optimized DMO.
The landing page https://support.sap.com/sltoolset always points to the SAP Notes (and guides) of the actual SUM SP version.
For downtime-optimized, it is SAP Note 2547309, and it describes the supported scenarios:
<Interference with other SUM scenarios: Scenario "DMO with System Move" does NOT allow to use "downtime-optimized DMO">

Kind regards,
Boris

[sudip_saha1]

Thanks, Boris, for the quick response. I see the SAP note saying "System Move" and "downtime-optimized" wouldn't work together. In this case, we will have to use downtime-optimized without system move because our DB size is 25TB+ and we will migrate biggest tables during uptime to shorter the overall downtime. For PAS and ASCS, we will install separately in new H/W host and connect the new PAS to HANA database. These installations will be vanilla install.

These are the steps i will do at high level-

1. Install ASCS in new host.


2. Install Vanilla HANA Database with ECC6.0 EHP8 initial version


3. Install PAS in new host connect to step 2, with ECC6.0 EHP8 initial version


4. Keep the PAS shutdown.


5. Run the Migration in old/current PAS host.


6. Once Migration completed to HANA, start new PAS connects to HANA.


7. Adjust all the DEFAULT and Instance profile parameters in new application server like old apps server.

 

Once question left is whether I will choose "Move ASCS instance" in the SUM DMO or not. Can you please confirm. Also let me know whether I am missing anything in the above steps.

[Boris_Rubarth]

Hi Sudip,

sorry to say that I can't evaluate or provide recommendation on approaches that are not SUM standard, like a manual move. If you run SUM on a PAS host, it will not offer the ASCS instance move.

Regards, Boris