Skip to main content

HANA System Replication - Prerequisites & Setup


Hey Folks! Welcome back to Hana high availability blog series. In our last blog we checked out operation & replication modes in hana system replication. If you haven't gone though that blog, you can checkout this link

In this blog we will be talking about the prerequisites of hana replication and it's setup. So let's get started.

When we plan to setup hana system replication, we need to make sure that all prerequisite steps have been followed. Let's have a look at these prerequisites.

HANA System Replication Prerequisites:

  • Primary & secondary systems should be up & running
  • HDB version of secondary should be greater than or equal to Primary database sever
  • But, for Active/Active(read enabled config), HDB version should be same on both sites.
  • System configuration/ini files should be identical on both sides
  • Replication happens for the whole system and can't be tenant/database specific
  • Number of worker nodes and role configuration on both sites should be same. Standby nodes need not to be same.
  • Systems should not be on the same host. Hostnames should be different.
  • Both systems should have same SID and instance number.
  • Replication related ports with default port offset 10000 should be available.
  • Initial backup should have been done for the primary system's databases.
  • Log mode should be 'normal'
  • Should have sidadm access
  • System PKI SSFS .key and the .dat files must be copied from the primary system to the secondary system
    • /usr/sap/<SID>/SYS/global/security/rsecssfs/data/SSFS_<SID>.DAT
    • /usr/sap/<SID>/SYS/global/security/rsecssfs/key/SSFS_<SID>.KEY
      For XS advanced, following files should also be copied
    • /usr/sap/<SID>/SYS/global/xsa/security/ssfs/data/SSFS_<SID>.DAT 
    • /usr/sap/<SID>/SYS/global/xsa/security/ssfs/key/SSFS_<SID>.KEY
  • In a system replication landscape the systems on all sites must run on platforms with the same byte order. System replication is supported between Intel little-endian and IBM Power little-endian systems
  • If you plan to add SAP HANA dynamic tiering to your landscape in the future, seeSAP Note 2447994 before you enable HANA system replication
Now let's see how to enable/disable hana replication and change replication mode. All below operations should be performed as <sid>adm

Setup/Enable SAP HANA System Replication:

  1. Login to primary and enable replication
    hdbnsutil -sr_enable --name=<Sitename>
    where, name -> can be anything

  2. Stop secondary server
    sapcontrol -nr <inst_no> -function StopSystem HDB

  3. Register replication on secondary
    hdbnsutil -sr_register --remoteHost=<primary_hostname> --remoteInstance=<Inst_no> --replicationMode=<sync/syncmem/async> --name=<Sitename_secondary> --operationMode=<logreplay/delta_datashipping>

  4. Start secondary server
    sapcontrol -nr <inst_no> -function StartSystem

  5. Replication check on Primary System
    hdbnsutil -sr_state

    cd /usr/sap/<SID>/HDB<inst_no>/exe/python_support
    $ python systemReplicationStatus.py

Disable SAP HANA System Replication with hdbnsutil

  1. Stop secondary system
    sapcontrol -nr <inst_no> -function StopSystem HDB

  2. Unregister the secondary system as follows:
    hdbnsutil –sr_unregister
    For other use cases of the command hdbnsutil –sr_unregister, see SAP Note 1945676.

  3. Disable system replication on the primary system as follows:
    hdbnsutil –sr_disable

  4. Start secondary server
    sapcontrol -nr <inst_no> -function StartSystem HDB

If system replication is out of sync and you need to register again the initial secondary system, use the command hdbnsutil –sr_register. It is not needed to unregister the secondary system before registering it again.

SAP HANA System Change Replication Mode

  1. Stop the secondary system using the command:
    sapcontrol -nr <inst_no> -function StopSystem

  2. Run the command:
    hdbnsutil -sr_changemode --mode=sync|syncmem|async

  3. Start the secondary system using the command:
    sapcontrol -nr <inst_no> -function StartSystem

To change operation mode, we need to re-register replication with the required mode.

That was all about prerequisites and setup of hana system replication. Hope you now have a better understanding of Hana System replication concepts.

Comments

  1. Mike17 November 2022 at 12:07

    Hello,
    Many Thanks for this blog.
    What happens when the primary site (hana system) has an error and that is then replicated to the secondary site.

    How does the secondary side know that there was an error on the primary side?

    Can I then start the secondary site ? Will it also have the same error?

    Many Thanks

    ReplyDelete
  2. Ziya23 August 2023 at 22:28

    ReplyDelete
  3. Anonymous2 December 2023 at 10:21

    Could you please help withsystem replication setup with auto-failover through pacemaker cluster?

    ReplyDelete

Post a Comment

You might find these interesting

How to properly Start/Stop SAP system through command line ?

Starting/stopping an SAP system is not a critical task, but the method that most of us follow to achieve this is sometimes wrong. A common mistake that most of the SAP admins do is, making use of the 'startsap' and 'stopsap' commands for starting/stopping the system.  These commands got deprecated in 2015 because the scripts were not being maintained anymore and SAP recommends not to use them as many people have faced errors while executing those scripts. For more info and the bugs in scripts, you can check the sap note 809477.  These scripts are not available in kernel version 7.73 and later. So if these are not the correct commands, then how to start/stop the sap system?  In this post, we will see how to do it in the correct way. SAP SYSTEM VS INSTANCE In SAP, an instance is a group of resources such as memory, work processes and so on, usually in support of a single application server or database server with
13 comments
Read more

sapstartsrv is not started or sapcontrol is not working

 What is sapstartsrv ? The SAP start service runs on every computer where an instance of an SAP system is started. It is implemented as a service on Windows, and as a daemon on UNIX. The process is called  sapstartsrv.exe   on Windows, and   sapstartsrv   on UNIX platforms. The SAP start service provides the following functions for monitoring SAP systems, instances, and processes. Starting and stopping Monitoring the runtime state Reading logs, traces, and configuration files Technical information, such as network ports, active sessions, thread lists, etc. These services are provided on SAPControl SOAP Web Service, and used by SAP monitoring tools (SAP Management Console,  SAP NetWeaver  Administrator, etc.). For more understanding use this link : https://help.sap.com/doc/saphelp_nw73ehp1/7.31.19/enUS/b3/903925c34a45e28a2861b59c3c5623/content.htm?no_cache=true How to check if it is working or not ? In case of linux , you can simply ps -ef | grep sapstartsrv In case of windows, you need
Post a Comment
Read more

ST03N : The chapter for all BASIS Admins

This blog is targeted to BASIS ADMINS Transaction for workload analysis statistical data changed over time are monitored using transaction code ST03 , now ST03N (from SAP R/3 4.6C) . With SAP Web AS 6.4 the transaction ST03 is available again. From time to time ST03 and ST03N has seen many changes but later in SAP NW7.0 ST03N has reworked in detail specially processing time is now shown in separate column. Main Use of ST03N  is to get detailed information on performance of any ABAP based SAP system. Workload monitor analyzes the statistical data originally collected by kernel. You can compare or analyze the performance of a single application server or multiple application server. Using this you start checking from the entire system and finding your way to that one application server and narrowing down to exact issue. By Default :- You see data of current day as default view , you can change the default view. Source of the image : sap-perf.ca Let's discuss the WORKLOAD MONITOR By D
4 comments
Read more

HANA hdbuserstore

The hdbuserstore (hana secure user store) is a tool which comes as an executable with the SAP Hana Client package. This secure user store allows you to store SAP HANA connection information, including user passwords, securely on clients. With the help of secure store, the client applications can connect to SAP HANA without the user having to enter host name or logon credentials. You can also use the secure store to configure failover support for application servers in a 3-tier scenario (for example, SAP Business Warehouse) by storing a list of all the hosts that the application server can connect to. To access the system using secure store, there are two connect options: (1)key and (2)virtualHostName. key is the hdbuserstore key that you use to connect to SAP HANA, while virtualHostName specifies the virtual host name. This option allows you to change where the hdbuserstore searches for the data and key files. Note
3 comments
Read more

How to resolve Common Error : Standard Template "sap_sm.xls" missing

Hey everyone, putting forward a common error we usually face when we have “ Excel inplace” functionality enabled in our SAP system. This error occurs when validity of the signature of SAP standard templates expired or were incorrectly delivered via support packages. We can reproduce the error by doing as below.. Click on “spreadsheet” icon after any SAP ALV grid view of data is on screen to make this data to export into excel directly from SAP.
1 comment
Read more

Work Process and Memory Management in SAP

Let’s talk about the entire concepts that are related to memory when we talk about SAP Application. Starting with few basic terminologies, Local Memory :  Local process memory, the operating system keeps the two allocation steps transparent. The operating system does the other tasks, such as reserving physical memory, loading and unloading virtual memory into and out of the main memory. Shared Memory :  If several processes are to access the same memory area, the two allocation steps are not transparent. One object is created that represents the physical memory and can be used by various processes. The processes can map the object fully or partially into the address space. The way this is done varies from platform to platform. Memory mapped files, unnamed mapped files, and shared memory are used.  Extended Memory : SAP extended memory is the core of the SAP memory management system. Each SAP work process has a part reserved in its virtual address space for extended memory. You can set
7 comments
Read more

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
2 comments
Read more

ABAP Dumps Analysis

Ever now and then have you heard about ABAP Dumps, We also have a joke everything in temporary in life except ABAP dumps for SAP Consultants. Lets try to understand ABAP dumps from perspective of a SAP BASIS Consultant. Dumps happen when an ABAP program runs and something goes wrong that cannot be handled by the program We have two broad categories of Dumps , In custom program Dumps and SAP provided program Dumps. Dumps that happen in the customer namespace ranges (i.e. own-developed code) or known as Custom Program , can usually be fixed by the ABAP programmer of your team. Dumps that happen in SAP standard code probably need a fix from SAP. You do not have to be an "ABAPer" in order to resolve ABAP dump issues. The common way to deal with them is to look up in ST22 How to correct the error ? Hints are given for the keywords that may be used to search on the note system. Gather Information about the issue  Go to System > Status and Check the Basis SP level as well as info
Post a Comment
Read more

Complete Guide : XPI Inspector Tool

Content of this blog :           What is an XPI Inspector Tool ? Why XPI Tool is used ? XPI standard URL How to check XPI Tool version ? How to Install/Update XPI version using TELNET How to Use XPI Tool ? References – SAP Notes What is XPI Inspector tool ?          -    XPI Inspector is a diagnostics web application developed by SAP that collects logs and debug traces from various PI components in a very simple way and is useful for SAP PI consultants, developers, and administrators to get more insights on an issue. Why XPI is used  – 1.  Used to collect traces and logs from Messaging system or XI module. 2. Used to collect the related information to solving the issues or improving the PI or PO systems’ performance. 3. Using XPI Inspector application you will be able to collect a lot of information about your system that will help you to learn about problems in the past, to analyze new and detect such at an early stage. 4. Performs certain number of configuration checks, such as SSL c
1 comment
Read more