SAP system migration blog series - part 1: migration overview



Summary:


This blog is part 1 of the blog series on SAP system migration. In this blog, we will provide overview about SAP migration, types of migration, their differences and usage scenario.


SAP migration overview: 


As the Greek philosopher, Heraclitus, said: “change is the only constant.” Same goes within SAP world too, often customer have to change the SAP systems along with its underlying components to meet the changing requirements, be it change from old hardware to new one, changing operating system, database. This change in SAP system components (DB, OS or Hardware) is termed as migration.


Before we go into details of migration, let’s understand architecture of a typical SAP system. 


An SAP system consist of SAP application instances, running on database (DB), hosted on operating system (OS), provisioned on hardware. Change in any one or more of these underlying components (DB, OS or hardware) warrant us to perform migration.



Types of migration: 

Broadly, there are two types of migration: Homogenous migration and Heterogenous migration


1. Homogenous migration: When an SAP system is moved to new hardware of similar architecture while keeping the underlying operation system and database same as source SAP system. 

Homogenous migration is often referred as AS-IS migration because we keep the target system configuration same as source system.




Important points to note: 

    • As rule of thumb, if SAP kernel type is not changing on the target system, then this type of migration falls under homogenous migration.
    • In homogenous migration, OS and Database type remains same in source and target system; however, their version may differ. For example, 
      • Source and target database is HANA but source is on HANA1.0 and target on HANA 2.0.
      • Source and target OS is SUSE Linux, but target OS SUSE version is higher.
      • Source OS version: Windows 2008, target OS version: Windows 2012 R2.
    • Change OS from SUSE Linux x86_64 to RedHat Linux x86_64 (or vice versa) is considered as homogenous migration as both are Linux based.
    • Hardware architecture of source and target server must be same. Thus, homogeneous migration is only possible with the following operating system platforms:

                                            Table 1: Source hardware type vs target in homogenous migration

                 Note: Endianness means the order in which a sequence of bytes is stored in the                                                         computer memory. For more information, see SAP Note 552464.

    • For homogenous migration, DB dependent method (backup/restore, HANA system replication in case of HANA DB, etc.…) or DB independent method (export/import) can be used. We will discuss homogenous migration in detail in upcoming blog.


Examples of homogenous migration: 


    • Shift from on-premises physical hardware or virtual infrastructure to virtualised environment on cloud or another datacenter but keeping OS, DB same.
    • Migrating system from old hardware (e.g., HP RX2800) which is not supported for S/4 HANA to new hardware (e.g., Superdome Flex 280) supported by S/4HANA
    • Conversion from on-premise ECC on HANA to S/4HANA cloud.
    • HANA Migration from scale-up server to scale-out server
    • Migration of SAP HANA from an existing AWS EC2 instance to an EC2 High Memory instance. Similar migration in other cloud providers like Azure and GCP.

2. Heterogenous migration: When an SAP system is moved to new hardware of similar or different architecture while changing either operating system or database or both.

Heterogenous migration is often referred as OS/DB migration.

 



                                                                    *Target has OS/DB/Hardware different than source


Important points to note: 


    • As rule of thumb, if SAP kernel type has to be changed on the target system, then this type of migration falls under heterogenous migration.
    • Hardware architecture of source or target can be different. For any combination other than table 1 shown in homogenous migration section, heterogenous migration is mandatory.
    • For Heterogeneous migration, DB independent method (export/import) is necessary. Also, migration key must be entered into the migration tool. Each OS/DB Migration requires its own key. It is assigned on the basis of the installation number and additional system-specific information. We will discuss heterogenous migration in detail in upcoming blog.

Examples of heterogenous migration: 


    • Change DB from HANA to anyDB (or vice versa)
    • Change OS from AIX to HP-UX or Solaris (or vice versa)
    • Change OS from Unix to Linux (or vice versa)
    • Change OS from Windows to Linux (or vice versa)
    • Change OS/DB from Windows/MSSQL to Linux/ASE (or vice versa)
    • Change from SAP HANA Big Endian to Little Endian (or vice versa).
    • The processor on the target host and source host does NOT use the same byte sorting.                        (little endian -> big endian; big endian -> little endian) like Intel-based to IBM Power Systems (Big-Endian) or vice versa.


Interesting trivia: 


Words- System ‘copy’ and ‘migration’ are often interchangeably used in SAP world. SAP uses mostly the word ‘copy’ (be it ‘homogenous system copy’ or heterogenous system copy’) and terms ‘Heterogeneous system copy’ as synonym for migration.


However, there is slight difference between system copy and migration: 


System copy:  It’s a process where you are copying an existing SAP system to another system which is either already there (like copy production system to quality system, often called system refresh) or copy into a new system like creating test, demo or training system or do homogenous migration to new hardware.


In short, system copy = system refresh/new system build using copy of source/homogenous migration



System migration: It’s a process of moving an existing SAP system to new host for example, moving on-premise SAP system to cloud infrastructure or any other datacenter, moving SAP system from old hardware, OS, database to new ones. 


In short, system migration = homogenous migration/heterogenous migration



Conclusion: 


Hope you have got the clear idea about SAP migration and its type. In the part2 of this blog series, we will talk in detail about homogenous migration, its various migration patterns, pros and cons, usage scenarios and tools to be used.


References and links for further study: 


    • System Copy Guide:
                  https://support.sap.com/en/tools/software-logistics-tools.html
                  ->System Provisioning
                  ->System Copy Option of Software Provisioning Manager


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