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I am Suresh Chinta, working on SAP HANA Cloud & SAP BTP Cloud/ AWS/Azure cloud consultant.I have experience in SAP Basis/Netweaver , S4HANA Cloud implementations / Support. I'm certified Microsoft Azure cloud & AWS professional. I have started this blog to share my knowledge with all those who are interested to learn & enhance their career.

Tuesday, October 27, 2020

 

HANA 1.0 upgrade scenarios

A lot of customers want to upgrade their HANA 1.0 databases toward to HANA 2.0. Usually this is not a big deal, if you have enough downtime. You can go straight on from HANA 1.0 >= 122.04 to any supported HANA 2.0 revision. The MDC conversion will take place automatically during the upgrade procedure. You need a revision >= 122.04 because there were some changes in the persistence layout which are needed for an upgrade to HANA 2.0 (see note 2372809). Best practice is to go for the latest HANA 1.0 revision and upgrade to the latest HANA 2.0 revision. But be careful if your HANA 1.0 SPS12 revision is newer than the HANA 2.0 revision it is not supported to upgrade (see note 1948334). Also check if your application is supported to run on HANA 2.0.

Another possible way (kudos to Nicholas Chang) is to create a backup on source DB and restore this one on the new target DB which is installed directly on HANA 2.0 with MDC. Here the MDC conversion will take place during the recovery procedure. But this can take a lot of time depending on the size and the underlying architecture, but is a valid option if your current hardware is not supported for HANA 2.0 or you want to change the location anyway. Details can be found in note 1642148.

 

But some customers are using HSR (HANA System Replication) and want to profit from the near zero downtime update (NZDU) feature with DBSL suspend (1913302 / 1984882). Another scenario is if you want to change the data center. For instance you want to change your hoster.
Here you want less downtime as possible. This means no upgrade steps between. This can be create some trouble because since HANA SPS01 the standard operation mode is MDC (see note 2423367). Does it work to sync from SDC (Single database container) to MDC? Just simple: not touching the old HANA instance and sync with HSR to the target HANA 2.0 revision. Is this possible?

There is some information in the documentation and notes which can be very confusing:

SAP HANA Tenant Databases Operations Guide
You can perform a near-zero downtime update of a single-container system to SAP HANA 2.0 SPS 01 in a system replication landscape. A single-container system will be automatically converted to a tenant database system during the update. Converting an SAP HANA system to a tenant database system is permanent and cannot be reversed.

Prerequisites

– The statistics server is not running as a separate server process (statisticsserver), but instead as an embedded service in the master index server. If this is not the case, migrate the statistics server to the embedded statistics service as described in SAP Note 1917938.
– The SAP HANA system has been installed with its server software on a shared file system (export options rw, no_root_squash).
– The SAP HANA system has been installed with the SAP HANA database lifecycle manager (HDBLCM).
– You are logged on as the system administrator user <sid>adm.

Perform one of the following procedures to update your system replication landscape to SAP HANA 2.0 SPS01:

Near-Zero Downtime Update (NZDU)

1. Update the secondary system using the SAP HANA database lifecycle manager. The migration to a tenant database system is triggered automatically.
2. Wait until the update has finished and all systems are in sync again. The replication will be possible in this situation although the primary is still a single-container system.
3. Perform a takeover to the updated secondary system. Only now the migration to a tenant database system is finalized for the secondary.
4. Update the primary system using the SAP HANA database lifecycle manager. The migration to a tenant database system is done automatically.
5. Wait until the update has finished and the primary system is up and running again.
6. Register this former primary system as the new secondary to the new primary (former secondary).

 

1999880 – FAQ: SAP HANA System Replication
Can I set up system replication between systems with different topologies?

The topology of primary and secondary site of a system replication scenario must be identical. As a consequence it isn’t possible to replicate from non-MDC to MDC (SAP Note 2101244) and vice versa, and it is also not possible to replicate from single-node to scale-out and vice versa.

2101244 – FAQ: SAP HANA Multitenant Database Containers (MDC)

Is it possible to convert SAP HANA 1.0 single container system to SAP HANA 1.0 MDC system with HANA System Replication?

No, conversion from single container to MDC with HANA System Replication is not supported. You would need to disable replication before starting the conversion else the conversion on secondary would fail with the below error.

SAP HANA Lifecycle Management – SAP HANA 1.00.122.17.1526900527

***************************************************************

10:03:43.088 – INFO: Start Date: 2018-10-26 – hdblcm

10:03:43.104 – INFO: Performing secondary system check

10:03:43.104 – ERR : The SAP HANA System cannot be converted to multitenant database containers, because it is a system replication site

10:03:43.105 – INFO: Summary of critical errors

10:03:43.104 – ERR : The SAP HANA System cannot be converted to multitenant database containers, because it is a system replication site

You would need to disable replication and need to perform the conversion on primary and all connected secondaries in case you have multitier replication.

Ok so there is some information that have to be sorted:
– it is not possible to sync from SDC to MDC
– it is possible to sync from MDC to MDC
– it is possible to sync HANA 1.0 revisions with HSR and upgrade the secondary to HANA 2.0 and sync back

 

 

In one of my projects we had a very special case. The old HANA 1.0 SDC instances should not be touched anymore and the target was on the IBM Power platform (PowerPC). This means SLES12/15 or RHEL >=7.2 on Little Endian and only HANA 2.0.

Scenario:
HANA 1.0 122.x SDC ====> HANA 2.0 >= SPS03 MDC

Do you see any direct supported scenario which is working and could solve this issue?

 

 

This is not supported by SAP. There is no direct way which is officially supported. So, why SAP creates such fundamental features like MDC which you have to use, and they are not compatible at all?

There are 3 possible solutions for this case:

1) HSR: HANA 1.0 SDC <=> HANA 2.0 SPS00 SDC

The easiest way which won’t touch the old source instance is to install a HANA 2.0 SPS00. Because SPS00 was the last official support package where you can choose between SDC and MDC. Just install it as SDC (interactive mode) und sync the HANA 1.0 with system replication.

But there is snag in it. You can only sync in a HANA which has the same revision or is newer. This means the last SPS00 revision was 2.02 and is not downloadable anymore (only with an OSS ticket). This means this solution is working from 122.04 through 122.10. If your source revision is above, you have to find another solution. So, if you follow the recommendation of SAP and upgrade your source revision to the latest one, you definitively can’t use it.

The most HANA 1.0 systems which I have seen are still on 122.05 or 122.08. Here the solution would be working.

2) HSR: HANA 1.0 MDC <=> HANA 2.0 MDC

This would be the easiest way, but you are touching the old source instance, because you have to convert it to MDC. This means an additional downtime. If your HANA 1.0 revision is newer than the latest HANA 2.0 one this solution won’t work.

For instance, the latest HANA 1.0 SPS12 revision is 122.22. The latest HANA 2.0 SPS02 is 24.07 and SPS03 Rev. 35. Currently it is not possible to upgrade or using HSR although your topology would allow it.

3) HSR: HANA 1.0 SDC <=> HANA 2.0 SPS01/02 SDC

HANA 2.0 SPS01/02 with SDC? Yes, this is not a typo. SAP integrated a backdoor if something won’t work with MDC. So, there is a hidden option/parameter:

./hdblcm --db_mode=single_container

This “dirty” option is still working though all revisions of SPS02. Since SPS03 they deactivated this one:

HANA 2.0 SPS02 Rev. 24.06

./hdblcm --action=install --ignore=check_signature_file --db_mode=single_container
SAP HANA Lifecycle Management - SAP HANA Database 2.00.024.06.1538035880
************************************************************************
Scanning software locations...
Detected components:
    SAP HANA Database (2.00.024.06.1538035880) in /int/software/sapcd/db/hana/hana_rev20_024_6/SAP_HANA_DATABASE/server
    SAP HANA AFL (incl.PAL,BFL,OFL,HIE) (2.00.024.0600.1538046631) in /int/software/sapcd/db/hana/hana_rev20_024_6/SAP_HANA_AFL/packages
    SAP HANA LCAPPS (2.00.024.0600.483443) in /int/software/sapcd/db/hana/hana_rev20_024_6/SAP_HANA_LCAPPS/packages
    SAP HANA Database Client (2.2.74.1536258378) in /int/software/sapcd/db/hana/hana_rev20_024_6/SAP_HANA_CLIENT_LINUX/client
    SAP HANA Smart Data Access (2.00.3.000.0) in /int/software/sapcd/db/hana/hana_rev20_024_6/SAP_HANA_SDA/packages

SAP HANA Database version '2.00.024.06.1538035880' will be installed.

 

HANA 2.0 SPS03 Rev. 35

./hdblcm --action=install --ignore=check_signature_file --db_mode=single_container
SAP HANA Lifecycle Management - SAP HANA Database 2.00.035.00.1545187853
************************************************************************
Scanning software locations...
Detected components:
    SAP HANA Database (2.00.035.00.1545187853) in /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_DATABASE/server
    SAP HANA AFL (incl.PAL,BFL,OFL) (2.00.035.0000.1545200735) in /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_AFL/packages
    SAP HANA LCAPPS (2.00.035.0000.485538) in /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_LCAPPS/packages
    SAP HANA Database Client (2.3.130.1542919958) in /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_CLIENT/client
    SAP HANA Smart Data Access (2.00.3.000.0) in /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_SDA/packages

Configuration error:
  Checking command line parameter '--db_mode' failed.
    Value 'single_container' is invalid. Please use one of: multiple_containers

This means you can create an SDC instance and be able to use HSR. I would prefer this option because you can avoid a lot of known issue regarding HANA 2.0 SPS00 (option 1) during HSR and don’t have to touch the source instance like in option 2.

After your instances are in sync you can upgrade to the latest HANA 2.0 SPS03/04 revision incl. MDC conversion during the upgrade. The only disadvantage of this scenario => it is not officially supported by SAP. I have successfully tested it with some revisions of HANA 1.0 SPS12 and as target HANA 2.0 Rev. 24.06.

Upgrade HANA 2.0 SPS02 Rev. 24.06 SDC  to SPS03 Rev. 35 MDC:

Summary before execution:
=========================
SAP HANA Database
   Update Parameters
      SAP HANA System ID: AN1
      Remote Execution: ssh
      Update Execution Mode: optimized
      Database User Name: SYSTEM
   Software Components
      SAP HANA AFL (incl.PAL,BFL,OFL)
         Do not install
      SAP HANA LCAPPS
         Do not install
      SAP HANA Database
         Update from version 2.00.024.06.1538035880 to 2.00.035.00.1545187853
         Location: /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_DATABASE/server
      SAP HANA Database Client
         Update from version 2.2.74.1536258378 to 2.3.130.1542919958
         Location: /int/software/sapcd/db/hana/hana_rev20_035_0/SAP_HANA_CLIENT/client
      SAP HANA Smart Data Access
         Do not install
Note: The upgrade of SAP HANA Database to this version will convert your system to multi-tenant database containers. This is a mandatory step. For more information, see SAP Note 2423367.

Do you want to continue? (y/n): y

 

For all customers and all upcoming migration and transition scenarios it would be great if SAP can create a supported solution, because if you have to convert the old system you have to adjust your concept and test an old HANA revision which you want to deactivate. I would appreciate any direct solution for this issue. In the next years a lot of customers will face such a situation. May be Ralf Czekalla or Craig Cmehil can address this topic.