SAP HANA Log-Based Replication


Transaction Log Based Data Replication Using Sybase Replication.


This replication method is only recommended for customers that have been invited to use this
technology during the RTC of the SAP HANA 1.0 product delivery. If you are not part of this RTC
group, SAP recommends using Trigger-Based Data Replication Using SAP Landscape Transformation (SLT) Replicator because of the rich feature set this replication technology offers.
The main components of this replication method are the Sybase Replication Agent which is part of the
source system, SAP ERP, and the Sybase Replication Server which is to be implemented in SAP HANA.


Replication Process in Detail


The following image  details the data replication process and introduces the additional components of this
replication method.



Initial Load and Simultaneous Delta Replication
The initial load of business data needs to be executed only one time to replicate the entire existing
dataset from the source system to the target, SAP In-Memory Database (IMDB).
The SAP HANA Load Controller, a component that resides in SAP HANA, coordinates the entire
replication process: It starts the initial load of source system data to the IMDB in SAP HANA, and
communicates with the Sybase Replication Server to coordinate the start of the delta replication.
The initial load can be executed while the source system is active. The process is described briefly below:

• The Load Controller initiates the initial load by calling the SAP R3load component in the source
system. This is a special version of R3load available as patch from the SAP Service Marketplace.
• The R3load on the source system exports the data for selected tables in the source system’s database
and directly transfers this data via sockets to the R3load component in SAP HANA without any intermediate files.
• The R3load on the target system imports the data into the IMDB.
• The login authentication between the source system and the target system is handled by the SAP Host Agent which is usually part of the source system.
In parallel to the initial load, the Sybase Replication Agent in the source system is started and detects
any data changes that occur while the initial load is already running to cover every single change. This
detection is realized by reading the logs for committed transactions of the source system’s database.

The Replication Agent uses the table metadata from the database to connect the raw log information
with the existing table names. In addition, the Replication Agent transfers all relevant raw log information
via TCP/IP connection to the Sybase Replication Server on the SAP HANA side. The Replication Server
creates SQL statements from the raw log information received and sends these statements to the
Sybase Enterprise Connect Data Access (ECDA).
The ECDA connects to the IMDB via Open Database Connectivity (ODBC) driver and replicates the
data changes from the source database by executing the SQL statements in the IMDB. The multi-version
concurrency control (MVCC) of the IMDB prevents from any locks.
Continuous Delta Replication After Initial Load
The continuous delta replication covers the running data changes in the source system in real time
once the initial load and the simultaneous delta replication have been completed: All further data changes
will be captured and continuously replicated from the source system to SAP HANA using the same
process as the simultaneous delta replication described above.

Required Software Components
This replication method requires the following components:
• SAP HANA Load Controller: Component that controls the entire replication process by triggering the initial load and coordinating the delta replication.
• Sybase Replication Agent: Component that does the log mining on the source database and relays all relevant information to the Replication Server.
• Sybase Enterprise Connect Data Access (ECDA): Component that connects to the target database (IMDB) via ODBC.
• Sybase Replication Server: Main component that accepts data from the Replication Agent, distributes and applies this data to the target database using ECDA/ODBC for connectivity.
• SAP Host Agent: Component that handles the login authentication between source system and target system.

Read related subjects:

SAP HANA REPLICATION DATA

SAP HANA Trigger-Based Replication

SAP HANA ETL-Based Replication

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