Tomas Krojzl

September 2011 Previous month Next month

Disclaimer

 

 

At the time of creation of this document there was no official SAP documentation available explaining details of SLT replication. This document is based on author's experience gained through working with SLT replication. Author was forced to make conclusions based on observing normal behavior of SAP system during SLT replication, based on studying SLT source code and based on experimenting with SLT configuration and replication.

 

The author therefore does not accept responsibility for potential damage done by applying information gained by reading this document. If you are not sure about result of your actions please contact SAP for further assistance.

 

1 Introduction

 

 

1.1 About this document

 

The goal of this document is to extend SAP documentation and to provide new information about SLT replication.

 

The reader is expected to download and read at least following SAP guide before reading this document.

 

SAP HANA 1.0 Installation Guide - Trigger-based Replication

https://service.sap.com/~sapidb/011000358700000604912011

 

2 Planning

 

2.1 Landscape selection


 

SLT can be installed either as a standalone component running on NetWeaver platform or inside an existing SAP system in case that the system is meeting specified criteria (see installation guide).


Option 1 - Separate SLT system

Option 1 - Separate SLT system

 

 

Option 2 - SLT installation in Source system

 

Option 2 - SLT installation in Source system

 

 

Note: Pictures above are taken from “SAP HANA Installation Guide – Trigger Based Replication” - pages 9 and 10 created by SAP.

 

SAP guide does not mention which option is preferred so here are some arguments supporting both options:

 

Arguments for Option 1 - Separate SLT system

  • SLT system needs special prerequisites – in long-term perspective (if such special requirements will remain) this might place unwanted limitations for underlying source system in relation to kernel or release upgrade
  • SAP recommends following specification for SLT installation (see below) – this is suggesting that SLT might take more than neglectable part of system resources (this mainly depends on the amount of replicated tables):
    • 100 GB of disk space
    • 16-32 GB RAM
    • 2-4 cores CPU
  • SLT system is using „never-ending“ jobs to perform replication – there must be enough background work processes available to ensure SLT functionality (for each configured SAP system you should have at least (6+n) background work processes where n is amount of replay jobs – see later chapters in next blogs for job overview)
  • SLT is raising a lot of false errors in system log – this is making it difficult to check for real errors happening in the SAP system (should be fixed by SAP Note 1625136)
  • SLT is generating an incredible amount of background jobs (6 jobs for each configured SAP system per cycle (usually around 2 minutes) – this can generate around 4320 jobs each day for each configured SAP system)
  • Because SLT is new - it still under development and frequent patching is expected
  • Specific skills and knowledge is required to not impact SLT configuration during system administration

     

    Arguments for Option 2 - SLT installation in Source system

    • Lower costs of ownership (no additional SAP system is needed)
    • Lower installation effort (only one add-on is required)

     

    Unless very specific cases I would suggest to install SLT as separate system. Benefits from standalone configuration are significantly outweighing increased costs of ownership.

     

    3 Preparation

     

    See SAP guide for instructions. If required update SAP kernel.

     

    Be sure to review also SAP note 1597627 - HANA connection for additional requirements including HANA client and DBSL installation.

     

    Comment about creation of secondary database connection into HANA (SAP note 1597627):

     

    During SLT configuration following database connections will be automatically created so there is no need to manually create additional database connection.

         <hana hostname>:<source system>:<target schema user>

         <hana hostname>:<source system>:<replication control user>

     

    Additional database connections might be needed for example for central monitoring using Solution Manager (then you should configure HANA connection in Solution Manager).

     

    4 Installation

     

    Complete SLT installation process is described in SAP guide and corresponding SAP notes. It can be summarized into following roadmap:

    • check if all prerequisites are met for both source system and SLT system
    • (if required) perform kernel upgrade or required adjustments
    • install HANA client on OS level of SLT system (and other systems that will require to connect into the HANA database)
      • download and unpack DBSL for HANA into kernel
      • execute hdbinst to install client
      • adjust environment variables
      • restart application (SAP system)
    • if SLT is installed as a separate system then install DMIS add-on in source system (note 1468391)
    • install DMIS add-on in SLT system (notes 1468391 and 1602938)
      • update SPAM to the latest version
      • use SAINT to install add-on component DMIS 2010_1_700
      • apply required support packages:
        • SAPK-91701INDMIS           DMIS 2010_1_700: SP 0001
        • SAPK-91702INDMIS           DMIS 2010_1_700: SP 0002
        • SAPK-91703INDMIS           DMIS 2010_1_700: SP 0003
        • SAPK-91704INDMIS           DMIS 2010_1_700: SP 0004

    Note:

    At the time of creation of this document the latest available support package was SP04. You should always install latest available support package because there are many critical fixes delivered.

    Note:

    In the installation guide is written that a special support package for HANA should be installed. This information is no longer valid because regular SP04 is already available which replaces this special support package. See SAP note 1602938 - DMIS_2010_1_700: Special Support Package for HANA 1.0 for more details.

    • create required user with following role in the source system
      • SAP_DMIS_USER
      • SAP_IUUC_REMOTE
      • SAP_IUUC_USER
      • SAP_SLOP_USER
    • in SLT system create new RFC connection to client in the source system from which you plan to replicate tables (in case where SLT is installed in the source system the RFC will point to itself)
    • you might need to implement ABAP corrections (in SLT system and in the monitoring system) in case you are not on the required support package level – see SAP note 1589983 - No DBCON entry possible for SAP In-Memory Database
    • (optional for DB monitoring) setup of a secondary connection to HANA database is optional and is not needed in SLT system (new database connections will be automatically created during SLT configuration)

    see SAP note 1597627 for instructions how to add a connection via transaction SM30 (maintenance of DB table DBCON)

    • activate required WebDynpro services (transaction SICF)

    /sap/bc/webdynpro/sap node - activate service iuuc_replication_config

    • add WebDynpro service in SAP menu (via right click on favorites)
    • configuration of SLT replication using WebDynpro service iuuc_replication_config

    see next blog for detailed explanation

     

     

    Second part (covering Post-Installation activities - applying SAP corrections, creating connection between source system and SAP HANA database, adjusting security and data provisioning) can be found here:

     

    SAP SLT (Trigger Based) Replication Made Easy - part 2: Post-Installation

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