Explaining the Management of SAP HANA With SAP Landscape Management

Objectives

After completing this lesson, you will be able to:

  • Perform takeover and fallback for SAP HANA using SAP Landscape Management
  • Explain how Near Zero Downtime Maintenance scenarios work with SAP Landscape Management

Configuration of SAP HANA System Replication

The SAP Landscape Management supports several SAP HANA specific operations.

SAP HANA system replication is a mechanism for ensuring the high availability of your SAP HANA system. When using the SAP HANA system replication, the continuous replication of data from a primary to a secondary system, including in-memory loading, and system replication facilitates rapid failover in the event of a disaster and productive operations can be resumed with minimal downtime. SAP HANA system replication is a prerequisite for SAP HANA operations like near-Zero Downtime Maintenance (nZDM) or Takeovers.

You can copy an original system to create an SAP HANA system replication tier for system replication. When doing this ensure your source system is enabled for configuration of system replication. Choose ConfigurationSystems[Choose your source system]Edit.

To start the SAP HANA system replication configuration process call choose ProvisioningSystem and AS. Choose the system on the left side of the screen and choose Configure System Replication.

A roadmap appears to guide you through the process of SAP HANA System Replication configuration.

Note

The figures and the animation show an outdated UI for entire workflow. The UI is now available in SAP UI5.

Available under ProvisioningSystems (tab)Create System Replication.

Sync and Operation Modes in Replication

SAP HANA System Replication – Possible Sync Modes in Replication

Log ModeDescription
Synchronous in-memory

The primary system commits the transaction after it receives a reply that the log was received by the secondary system, but before it has been persisted.

Synchronous

The primary system does not commit a transaction until it receives confirmation that the log has been persisted in the secondary system.

Asynchronous

The primary system sends redo log buffers to the secondary system asynchronously. The primary system commits a transaction when it has been written to the log file of the primary system and sent to the secondary system through the network.

SAP HANA System Replication — Possible Operation Modes in Replication

Operation ModeDescription
delta_datashipping

This mode establishes a system replication where occasionally (by default every 10 minutes) a delta data shipping takes place in addition to the continuous log shipping. The shipped redo log is not replayed on the secondary site.

logreplay

This mode does not require a delta data shipping anymore. Additionally, the shipped redo log is continuously replayed on the secondary site.

logreplay_readaccessThis mode is required for replication to an Active/Active (read enabled) secondary system. It is similar to the log replay operation mode regarding the continuous log shipping, the redo log replay on the secondary system, as well as the required initial full data shipping and the takeover.

Hosts

You can specify the target hosts for the new system. To specify the host, choose the type of target host. To prepare and start the target system on an existing host choose Use Existing Host. If you have a configured virtualization manager and want to provision a new host of your system is locally installed on a virtual host, choose Provision New Host and navigate through the workflow.

SAP Landscape Management is able to configure and create virtual host names and physical host names for newly provisioned virtual machines. If you do not want Landscape Management to create host names, you have to create these host names up-front on your name server. Define the combination of virtual host—name and instance. To assign an IP address automatically by using the range of IPs you specified when configuring the landscape, choose Auto IP Address. You can choose a previously created network.

Storage

You can manage the cloning of volumes of the source system to the target system within the Storage step. It is recommended to do a full clone of the volumes for the creation of a system replication. This step is only applicable if you use storage based provisioning.

Rename

You can change the preselected release configuration for each instance, if required. For some database release configurations, you must specify the database administrator and manager credentials of the source system. To see if your system is ready for system copy, choose Execute Prerequisite Checker.

SAP HANA System Replication – Summary

Summary shows you selection. You can execute the operation by choosing Configure System Replication.

SAP Landscape Management creates a new SAP HANA database and configures the SAP HANA system replication. You are forwarded to the monitoring screen.

If you already have two SAP HANA databases available that meet the SAP HANA system replication, you can execute the procedure described in the figure, SAP HANA System Replication - Configuring the Primary System. Choose Operations & MaintenanceOperationsInstances and choose HANA System ReplicationEnables System Replication for the primary system, and enter a site name for the system.

To set up the secondary system for system replication, you must configure and register it with the primary system. To do this, the secondary side must have the status Not Running. Choose Operations & MaintenanceOperationsInstances and choose HANA System ReplicationRegister Secondary for System Replication.

The figure shows the field to enter the secondary configuration data.

These are the possible entries, which you must provide from the following table:

Secondary System Configuration Data

Custom ParameterDescription
ModeChoose the replication log mode.
Operation ModeChoose the replication operation mode.
Remote HostEnter the name of the primary host that the secondary system registers with.
Site NameEnter an alias to represents the secondary site.

De-listing the Secondary Tier

Start your secondary sites as the last step.

You can de-list a secondary site form its source, for example to disable system replication. To do this, the secondary side must have the status Not Running, while the primary side needs to have the status Running. Choose Operations & MaintenanceOperationsInstances and choose the SAP HANA secondary side of the system where you want to disable the SAP HANA system replication.

You can disable system replication on the primary system or on the tier 2 secondary system (the source system). To do this choose Operations & MaintenanceOperationsInstances and choose the SAP HANA primary side of the system where you want to disable SAP HANA system replication.

Operations for SAP HANA

SAP Landscape Management takes care of the nZDM process until it reaches the point where you can perform the maintenance. SAP Landscape Management waits and holds this step until you confirm that you have finished the maintenance and will continue afterwards.

Implement a HANA System Replication

Business Scenario

In this exercise, you will perform a SAP HANA system replication.

Exercise Options

You can perform this exercise in two ways:

  1. Start the exercise. From the entry screen, choose Start Tutorial to watch the simulation.
  2. Start the exercise. From the entry screen, choose Open PDF Document. This document contains all required steps to perform this exercise in your own system.

Destroy a HANA System Replication

Business Scenario

In this exercise, you will destroy a SAP HANA system replication.

Exercise Options

For this exercise, we do not offer a simulation. So regard the steps of this exercise as a "how-to", when you have to destroy a SAP HANA System replication.

You can perform this exercise in the following way: Follow the steps below in your own system landscape.

Task 1: Destroy a SAP HANA System Replication

Steps

  1. Destroy the SAP HANA System Replication of the system A4H.

    1. Navigate to ProvisioningA4H SystemProvisioningReplication ProcessesDestroy System Replication and follow the road map.

    2. Make sure that all volumes are selected in the Delete Storage Volumes step.

    3. Choose Next.

    4. In the Delete Host Names step, choose Next.

    5. Check the Summary step and click Execute to start the process.

      It should look like this:

  2. Monitor the activity.

    1. Go to MonitoringActivities.

      It should look like this:

Near Zero Downtime Operations

Benefits of SAP HANA Management are:

  • Simplified provisioning and management of SAP HANA multitenant database container (MDC) setups.

  • Fully automated systems refresh procedure for SAP HANA using backup and restore.

  • Provisioning Tenant Databases:

    • Copy a Tenant Database

    • Refresh a Tenant Database

    • Rename a Tenant Database

  • Fully automated procedure to setup and monitor SAP HANA system replication.

  • Fully automated procedure for SAP HANA failback and nZDM takeover.

  • nZDM maintenance for SAP HANA (for example, operating system (OS) updates, SAP HANA upgrades, and hardware maintenance).

  • nZDM SAP HANA Update (on Primary Tier).

SAP HANA System Replication Setup

The figure, SAP HANA System Replication Setup I, shows the difference between the standard procedure and SAP Landscape Management procedure for system replication in SAP HANA.

SAP HANA system replication is a prerequisite for SAP HANA operations like nZDM Maintenance or Takeovers. All the required steps are automated together with built-in best practices.

For further details check the official documentation: http://help.sap.com/nwlvm.

SAP HANA Takeover

The figure, SAP HANA Takeover, shows the difference between the standard procedure and the SAP Landscape Management procedure for an SAP HANA Takeover.

The figure, SAP HANA nZDM Takeover, shows the difference between the standard procedure and SAP Landscape Management procedure for an SAP HANA nZDM Takeover.

A takeover can be necessary due to several reasons including the following:

  • The primary side is unavailable due to a disaster.

  • A downtime is planned for the primary side.

The SAP Landscape Management offers the following:

  • Takeover:

    • For disaster.

    • No preloading on the secondary side.

  • Near Zero Downtime Takeover:

    • Minimizes planned business downtime during takeover to the secondary system.

    • Preloading of data in-memory (before takeover) to speed up the takeover procedure.

    • Applications are automatically quiesced or unquiesced (before and after a takeover) to ensure consistency.

Operations for SAP HANATakeover - Process

The figure, Operations for SAP HANA Takeover - Process, shows the process for an SAP HANA Takeover.

The Takeover Process consists of the following steps:

  1. The former primary system has the status Not Running and the former secondary system has the status Running.

  2. To avoid data inconsistencies, the system automatically stops a running primary database during the Takeover process. Clients cannot access the database.

  3. The system deactivates all the active virtual cluster IP addresses on the primary system.

  4. The system activates all inactive virtual cluster IP addresses on the secondary system.

nZDM Scenario for SAP HANA

The figure, nZDM Scenario for SAP HANA — On SAP HANA Secondary, shows the initial setup, before the nZDM procedure on secondary SAP HANA systems is performed.

The figure, nZDM Scenario for SAP HANA - Disable System Replication, shows that the SAP HANA System Replication is deactivated by SAP Landscape Management.

The figure, nZDM Scenario for SAP HANA – Perform Maintenance on Secondary System, shows the point in time when SAP Landscape Management pauses the nZDM procedure and waits until you have performed the manual maintenance.

The figure, nZDM Scenario for SAP HANA – Re-enable System Replication, shows that the nZDM procedure reenables the SAP HANA system replication after the successful maintenance has been confirmed in SAP Landscape Management.

The figure, nZDM Scenario for SAP HANA - On SAP HANA Primary, shows the initial setup, before the maintenance on the primary SAP HANA systems is performed.

The figure, nZDM Scenario for SAP HANA - Perform Takeover, shows how to perform a takeover on an SAP HANA Primary system.

To perform a takeover on a primary system, do the following:

  • Register the Secondary system as the new (temporary) Primary system.

  • Redirect SAP HANA clients to a new (temporary) Primary system.

  • Stop the old Primary system.

The figure, nZDM Scenario for SAP HANA — Perform Maintenance on Primary System, shows how to perform maintenance on an SAP HANA Primary system.

The figure, nZDM Scenario for SAP HANA — Prepare Failback, shows how to prepare failback on an SAP HANA Primary system.

The figure, nZDM Scenario for SAP HANA – Perform Failback, shows how to perform failback on an SAP HANA Primary system.

The figure, SAP HANA nZDM Maintenance, shows the difference between standard procedure and SAP Landscape Management procedure in SAP HANA for nZDM maintenance.

The figure, Start the nZDM in SAP Landscape Management in Secondary Tier, shows how to start the nZDM (secondary) via the operation interface in SAP Landscape Management.

The figure, Start the nZDM in SAP Landscape Management in Primary Tier, shows how to start the nZDM (primary) via the operation interface in SAP Landscape Management.

The figure, SAP HANA Failback – Procedures, shows the differences between standard procedure and SAP Landscape Management procedure for SAP HANA Failback.

Once your original primary system is operational again after a disaster or planned downtime, you can failback to your original primary system.

HA/DR Provider Hook

The SAP HANA nameserver provides a Python-based API, which is called at important points of the host auto-failover and system replication takeover process.

By using the SAP HANA replication status repositories and the HA/DR Provider Hooks, you can ensure that SAP HANA system replication is in sync before performing a takeover process using SAP Landscape Management.

This should prevent losing data when performing a takeover.

Configure the Replication Status Repository on your primary SAP HANA database in SAP Landscape Management:

Maximum Accepted Age of Replication Status
  • Maximum accepted age of the status on the NFS share.

  • If age is older, the status is considered out of sync.

Repository
Select the previously created repository configuration.
Installation Directory of HA/DR Provider Scripts
  • Define the directory, where to store the HA/DR Provider scripts.

  • Default directory: /hana/shared/<HANA SID>/hooks/LaMa.

Strict handling

To stop processing on the primary instance in case the replication status share is not available and replication is no longer in sync, set Strict Handling to True.

Timeout
This is the maximum amount of time the primary instance will wait for the hook in case of a stale NFS share.
Interval of File System Check
Interval of checking the File System.
Note
Primary SAP HANA and the application server will be stopped during the configuration.

SAP HANA Tenant Database - Moving a Tenant Database

Using SAP HANA system replication mechanisms, SAP HANA tenant databases can be copied and moved securely and conveniently from one SAP HANA system to another:

  • Respond flexibly to changing resource requirements and manage your system landscape efficiently.

  • After a move, the original tenant database is deleted, and the new tenant database takes over.

  • Also available as near-zero downtime tenant move.

Implement Near Zero Downtime Operations for SAP HANA

Business Scenario

The following tasks will explain the new SAP Landscape Management near Zero Downtime Operations for SAP HANA. After performing a near Zero Downtime (nZD) Takeover operation for high availability or maintenance purposes, a Failback will be performed to return to the original condition.

The last task will cover the execution of the near Zero Downtime Maintenance for SAP HANA.

Exercise Options

You can perform this exercise in two ways:

  1. Start the exercise. From the entry screen, choose Start Tutorial to watch the simulation.
  2. Start the exercise. From the entry screen, choose Open PDF Document. This document contains all required steps to perform this exercise in your own system.

Implement Near Zero Downtime Operations for SAP HANA - Part 1

Implement Near Zero Downtime Operations for SAP HANA - Part 2

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