VENKAT SAP HANA

SAP HANA backup and recovery is used to perform HANA system backups and recovery of system in case of any database failure.

Overview Tab

It tells the status of currently running data backup and last successful data backup.

Backup now option can be used to run data backup wizard.

Configuration Tab

It tells about the Backup interval settings, file based data backup settings and log based data backup setting.

Backup Interval Settings

Backint settings give an option to use third party tool for data and log back up with configuration of backing agent.

Configure the connection to a third-party backup tool by specifying a parameter file for the Backint agent.

File and Log Based Data Backup Settings

File based data backup setting tells the folder where you want to save the data backup on HANA system. You can change your backup folder.

You can also limit the size of data backup files. If system data backup exceeds this set file size, it will split across the multiple files.

Log backup settings tell the destination folder where you want to save log backup on external server. You can choose a destination type for log backup

File − ensures that sufficient space in system to store backups

Backint − is special named pipe exists on file system but require no disk space.

You can choose backup interval from drop down. It tells the longest amount of time that can pass before a new log backup is written. Backup Interval: It can be in seconds, minutes or hours.

Enable Automatic log backup option: It helps you to keep log area vacant. If you disable this log area will continue to fill and that can result database to hang.

Open Backup Wizard − to run the backup of system.

Backup wizard is used to specify backup settings. It tells the Backup type, destination Type, Backup Destination folder, Backup prefix, size of backup, etc.

When you click on next → Review Backup settings → Finish

It runs the system backups and tells the time to complete backup for the each server.

Recovery of HANA System

To recover SAP HANA database, the database needs to be shut down. Hence, during recovery, end users or SAP applications cannot access the database.

Recovery of SAP HANA database is required in the following situations −

A disk in the data area is unusable or disk in the log area is unusable.
As a consequence of a logical error, the database needs to be reset to its state at a particular point in time.
You want to create a copy of the database.

How to recover a HANA system?

Choose HANA system → Right click → Back and Recovery → Recover System

Types of recovery in HANA system

Most Recent State − Used for recovering the database to the time as close as possible to the current time. For this recovery, the data backup and log backup have to be available since last data backup and log area are required to perform the above type recovery.

Point in Time − Used for recovering the database to the specific point in time. For this recovery, the data backup and log backup have to be available since last data backup and log area are required to perform the above type recovery

Specific Data Backup − Used for recovering the database to a specified data backup. Specific data backup is required for the above type of recovery option.

Specific Log Position − This recovery type is an advanced option that can be used in exceptional cases where a previous recovery failed.

Note − To run recovery wizard you should have administrator privileges on HANA system.

SAP HANA database persistence layer is responsible to manage logs for all the transactions to provide standard data back up and system restore function.

It ensures that database can be restored to the most recent committed state after a restart or after a system crash and transactions are executed completely or completely undone. SAP HANA Persistent Layer is part of Index server and it has data and transaction log volumes for HANA system and in-memory data is regularly saved to these volumes. There are services in HANA system that has their own persistence. It also provides save points and logs for all the database transactions from the last save point.

Why does SAP HANA database need a Persistent Layer?

Main memory is volatile therefore data is lost during a restart or power outage.
Data needs to be stored in persisted medium.
Backup & Restore is available.
It ensures that the database is restored to the most recent committed state after a restart and that transaction are either completely executed or completely undone.

Data and Transaction Log Volumes

Database can always be restored to its most recent state, to ensure these changes to data in the database are regularly copied to disk. Log files containing data changes and certain transaction events are also saved regularly to disk. Data and logs of a system are stored in Log volumes.

Data volumes stores SQL data and undo log information and also SAP HANA information modeling data. This information is stored in data pages, which are called Blocks. These blocks are written to data volumes at regular time interval, which is known as save point.

Log volumes store the information about data changes. Changes that are made between two log points are written to Log volumes and called log entries. They are saved to log buffer when transaction is committed.

Savepoints

In SAP HANA database, changed data is automatically saved from memory to disk. These regular intervals are called savepoints and by default they are set to occur every five minutes. Persistence Layer in SAP HANA database performs these savepoint at regular interval. During this operation changed data is written to disk and redo logs are also saved to disk as well.

The data belonging to a Savepoint tells consistent state of the data on disk and remains there until the next savepoint operation has completed. Redo log entries are written to the log volumes for all changes to persistent data. In the event of a database restart, data from the last completed savepoint can be read from the data volumes, and redo log entries written to the log volumes.

Frequency of savepoint can be configured by global.ini file. Savepoints can be initiated by other operations like database shut down or system restart. You can also run savepoint by executing the below command −

ALTER System SAVEPOINT

To save data and redo logs to log volumes, you should ensure that there is enough disk space available to capture these, otherwise the system will issue a disk full event and database will stop working.

During the HANA system installation, following default directories are created as the storage location for data and log volumes −

/usr/sap/<SID>/SYS/global/hdb/data
/usr/sap/<SID>/SYS/global/hdb/log

These directories are defined in global.ini file and can be changed at later stage.

Note that Savepoints do not affect the performance of transactions executed in HANA system. During a savepoint operation, transactions continue to run as normal. With HANA system running on proper hardware, impact of savepoints on the performance of system is negligible.

SAP HANA alert monitoring is used to monitor the status of system resources and services that are running in the HANA system. Alert monitoring is used to handle critical alerts like CPU usage, disk full, FS reaching threshold, etc. The monitoring component of HANA system continuously collects information about health, usage and performance of all the components of HANA database. It raises an alert when any of the component breaches the set threshold value.

The priority of alert raised in HANA system tells the criticality of problem and it depends on the check that is performed on the component. Example − If CPU usage is 80%, a low priority alert will be raised. However, if it reaches 96%, system will raise a high priority alert.

The System Monitor is the most common way to monitor HANA system and to verify the availability of all your SAP HANA system components. System monitor is used to check all key component and services of a HANA system.

You can also drill down into details of an individual system in Administration Editor. It tells about Data Disk, Log disk, Trace Disk, alerts on resource usage with priority.

Alert tab in Administrator editor is used to check the current and all alerts in HANA system.

It also tells about the time when an alert is raised, description of the alert, priority of the alert, etc.

SAP HANA monitoring dashboard tells the key aspects of system health and configuration −

High and Medium priority alerts.
Memory and CPU usage
Data backups

MDX Provider is used to connect MS Excel to SAP HANA database system. It provides driver to connect HANA system to Excel and is further, used for data modelling. You can use Microsoft Office Excel 2010/2013 for connectivity with HANA for both 32 bit and 64 bit Windows.

SAP HANA supports both query languages − SQL and MDX. Both languages can be used: JDBC and ODBC for SQL and ODBO is used for MDX processing. Excel Pivot tables use MDX as query language to read data from SAP HANA system. MDX is defined as part of ODBO (OLE DB for OLAP) specification from Microsoft and is used for data selections, calculations and layout. MDX supports multidimensional data model and support reporting and Analysis requirement.

MDX provider enables the consumption of Information views defined in HANA studio by SAP and non-SAP reporting tools. Existing physical tables and schemas presents the data foundation for Information models.

Once you choose SAP HANA MDX provider from the list of data source you want to connect, pass HANA system details like host name, instance number, user name and password.

Once the connection is successful, you can choose Package name → HANA Modeling views to generate Pivot tables.

MDX is tightly integrated into HANA database. Connection and Session management of HANA database handles statements that are executed by HANA. When these statements are executed, they are parsed by MDX interface and a calculation model is generated for each MDX statement. This calculation model creates an execution plan that generates standard results for MDX. These results are directly consumed by OLAP clients.

To make MDX connection to HANA database, HANA client tools are required. You can download this client tool from SAP market place. Once installation of HANA client is done, you will see the option of SAP HANA MDX provider in the list of data source in MS Excel.

Open SAP HANA Studio → Create Schema under Catalog tab. <Start here>

Prepare the data and save it to csv format. Now create file with “ctl” extension with following syntax −

---------------------------------------
import data into table Schema."Table name"
from 'file.csv'
records delimited by '\n'
fields delimited by ','
Optionally enclosed by '"'
error log 'table.err'
-----------------------------------------

Transfer this “ctl” file to the FTP and execute this file to import the data −

import from ‘table.ctl’

Check data in table by going to HANA Studio → Catalog → Schema → Tables → View Content

Direct Extractor Connection data replication reuses existing extraction, transformation, and load mechanism built into SAP Business Suite systems via a simple HTTP(S) connection to SAP HANA. It is a batch-driven data replication technique. It is considered as method for extraction, transformation, and load with limited capabilities for data extraction.

DXC is a batch driven process and data extraction using DXC at certain interval is enough in many cases. You can set an interval when batch job executes example: every 20 minutes and in most of cases it is sufficient to extract data using these batch jobs at certain time intervals.

Advantages of DXC Data Replication

This method requires no additional server or application in the SAP HANA system landscape.
DXC method reduces complexity of data modeling in SAP HANA as data sends to HANA after applying all business extractor logics in Source System.
It speeds up the time lines for SAP HANA implementation project
It provides semantically rich data from SAP Business Suite to SAP HANA
It reuses existing proprietary extraction, transformation, and load mechanism built into SAP business Suite systems over a simple HTTP(S) connection to SAP HANA.

Limitations of DXC Data Replication

Data Source must have a predefined mechanism for extraction, transformation and load and if not we need to define one.
It requires a Business Suite System based on Net Weaver 7.0 or higher with at least below SP: Release 700 SAPKW70021 (SP stack 19, from Nov 2008).

Configuring DXC Data Replication

Enabling XS Engine service in Configuration tab in HANA Studio − Go to Administrator tab in HANA studio of system. Go to Configuration → xsengine.ini and set instance value to 1.

Enabling ICM Web Dispatcher service in HANA Studio − Go to Configuration → webdispatcher.ini and set instance value to 1.

It enables ICM Web Dispatcher service in HANA system. Web dispatcher uses ICM method for data read and loading in HANA system.

Setup SAP HANA Direct Extractor Connection − Download the DXC delivery unit into SAP HANA. You can import the unit in the location /usr/sap/HDB/SYS/global/hdb/content.

Import the unit using Import Dialog in SAP HANA Content Node → Configure XS Application server to utilize the DXC → Change the application_container value to libxsdxc

Creating a HTTP connection in SAP BW − Now we need to create http connection in SAP BW using transaction code SM59.

Input Parameters − Enter Name of RFC Connection, HANA Host Name and <Instance Number>

In Log on Security Tab, enter the DXC user created in HANA studio using basic Authentication method −

Setting up BW Parameters for HANA − Need to Setup the Following Parameters in BW Using transaction SE 38. Parameters List −

PSA_TO_HDB_DESTINATION − we need to mention where we need to move the Incoming data (Connection Name created using SM 59)
PSA_TO_HDB_SCHEMA − To which Schema the replicated data need to assign
PSA_TO_HDB − GLOBAL To Replicate All data source to HANA. SYSTEM – Specified clients to Use DXC. DATASOURCE – Only Specified Data Source are used for
PSA_TO_HDB_DATASOURCETABLE − Need to Give the Table name having the List of data sources which are used for DXC.

Data Source Replication

Install data source in ECC using RSA5.

Replicate the metadata using specified application component (data source version Need to 7.0, if we have 3.5 version data source we need to migrate that. Active the data Source in SAP BW. Once data source is activated in SAP BW it will create the following Table in Defined schema −

/BIC/A<data source>00 – IMDSO Active Table
/BIC/A<data source>40 –IMDSO Activation Queue
/BIC/A<data source>70 – Record Mode Handling Table
/BIC/A<data source>80 – Request and Packet ID information Table
/BIC/A<data source>A0 – Request Timestamp Table
RSODSO_IMOLOG - IMDSO related table. Stores information about all data sources related to DXC.

Now data is successfully loaded into Table /BIC/A0FI_AA_2000 once it is activated.