SAP HANA Backup

 SAP HANA Persistence

To ensure optimal performance, the SAP HANA database holds most of its data in-memory. However, it still uses persistent storage to provide a fallback in case of failure.

 


During normal database operation, data is automatically saved from memory to disk at regular savepoints. Additionally, all data changes are recorded in the redo log. The redo log is saved from memory to disk with each committed database transaction. After a power failure, you can restart the database as you would with any disk-based database. It then returns to its last consistent state by replaying the redo log since the last savepoints.

Although savepoints and log writing protect your data against power failures, savepoints do not help if the persistent storage itself is damaged. To protect against data loss because of disk failures, backups are required. Backups save the payload (the actual data) of the data area and log area to different locations.

 


Types of Back-ups:

1.Data Backup

1)   Full or complete Backup

2)   Delta Backup

    - Differential Backup

    - Incremental Backup

3)   Storage Snapshot

 2. Log Backup (will be covered at the bottom)




Destinations for Backups :

You can specify whether data and log backups are written to the file system (see SAP Note1820529 ), or using third-party backup tools (see SAP Note 1730932 ). The BACKINT software development kit (SDK) for the SAP HANA interface performs all the actions needed to write the backup data to external storage. The backup tools communicate directly with the SAPHANA database through the BACKINT SDK for the SAP HANA interface.

BACKINT SDK for SAP HANA

BACKINT SDK for SAP HANA is an application programming interface (API) that can be implemented by a third-party backup agent. It has the following features:

● It provides functions for backup, recovery, query, and delete.

● The third-party backup agent runs on the SAP HANA server and communicates with the third-party backup server.

● Backups are transferred through pipes.

● It has full integration with SAP HANA studio (configuration and execution of    backups to BACKINT).

·         It can be configured for data backups and for log backups.

 

Note:
SAP certification is required for BACKINT SDK for SAP HANA implementations by third-party vendors.

 Backup of Multitenant Database Containers :


·         Points to Note :

·         Backups can only be created when SAP HANA is online. All the configured SAP HANA services must be running.

·         While backups are being created, the impact on system performance is negligible, and users can continue to work normally.

·         The system database plays a central role. It can initiate backups of both the system database itself and individual tenant databases.

·     A tenant database can create its own backups without the need to connect through the system database using onlyHana Cockpit (but not in Studio)

·         System database and tenant databases have their own backup catalogs.

·         Backup and recovery always apply to the whole database. You cannot back up and recover individual database objects.

·         SAP HANA backups created with release 1.0 SPS10 or newer can be used to    recover to SAP HANA 2.0.

·         A backup of an SAP HANA single-container system can only be recovered to a tenant database.

·         A backup of an SAP HANA single-container system cannot be recovered to a system database.




Each backup file name contains the following elements:

<<path>/<prefix>_<suffix>>.

·         The <path> is optional. If no complete path is specified, the default backup location is used.

·         You can specify a <prefix> for the backup file name or you can use the prefix proposed by the system.

·         The system adds a unique <suffix> to each backup file name that indicates the volume ID and the partition ID.

Ex:

HEP_HANA_FULL_HEP_DB_2021_04_27:02:00_databackup_2_4

 PREFIX - CDB ( Complete data backup)

$DATETIME ( DATE TIME)
$SUFFIX ( Default value as it come _databackup_ *)

Example:

Below is an example of a set of backups from one data backup.

</backup/data/COMPLETE_DATA_BACKUP_databackup_0_1>

</backup/data/COMPLETE_DATA_BACKUP_databackup_1_1>

</backup/data/COMPLETE_DATA_BACKUP_databackup_2_1>

In the above example, the <path> is </backup/data/>, the <prefix> is <COMPLETE_DATA_BACKUP>. <databackup_0_1> is the suffix, which is automatically added by the system. In the suffix, <0> is the volume ID, and <1> is the partition ID


BACKINT location :  /usr/sap/SID/SYS/global/hdb/backint/DB_SID/  can’t be changed

 Data File Location : /usr/sap/SID/HDB20/backup/data

 Log File Location                      “                         /log

 Note:

The default backup destination can only be changed for file-based backups.Backups made using third-party tools always use the destination /usr/sap/<SID>/SYS/global/hdb/backint. Because of this, you cannot change the backup destination for third-party tools.

 To estimate the size of a backup, you can use the system table M_BACKUP_SIZE_ESTIMATIONS in the SQL Editor in the SAP HANA studio. This system table contains information about the used blocks.



Performing Backups Using SAP HANA Cockpit

 

1.In the SAP HANA cockpit, choose Manage database backups  under DB Administration.

 

2. To open the backup settings page, choose the Create Backup button at the top of the backup catalog.

 3. Select the type of the data backup from one of the following:

 ● Complete Data Backup

● Differential Data Backup

● Incremental Data Backup

 4. Specify the location (directory) and the backup file prefix to use and choose Back Up.

The SAP HANA Cockpit uses the time stamp for the backup file prefix by default.

The default location shows the path specified in global.ini under the backup parameter

basepath_databackup .

5. Once you have started the backup, the progress is displayed.

Overview of Backup Operations

Once you have started the backup, the progress is displayed. When the backup is finished, the backup details are shown.

You can cancel a running data backup from the progress details screen.


SYSTEM DB:



 

TENANT DB:



 



Overview of Back-ups:


Performing a Data Backup Using SAP HANA Studio

 To create a data backup using SAP HANA Studio, perform the following steps:

1. In the Navigator view, select the system that you want to back up.

2. From the context menu, choose Back Up .

3. Select the type of data backup from one of the following:

    ● Complete Data Backup

    ● Differential Data Backup

    ● Incremental Data Backup

4. Specify the location (directory) and the backup file prefix to use, and choose Next

The default location shows the path specified in global.ini under the       basepath_databackup backup parameter.

5. When all the settings are correct, choose Finish . The backup then starts. The progress of the backup is shown for all types of services (for example, the name server, and indexservers).When all the volumes have been backed up, a confirmation message display.

 

     Performing a Data Backup Using SQL Commands

You can enter SQL commands either by using the SQL editor in SAP HANA studio, or by using the hdbsql program on the command line

 

             

              Scheduling Backups Using SAP HANA Cockpit

 Data backups can be scheduled with the SAP HANA cockpit. You can schedule complete, incremental, or differential backups, as well as backups to file or third-party (BACKINT) tools.


Note:

-       SAP HANA cockpit 2.0 cannot schedule backups for SAP HANA 1.0 databases.

-     Currently snapshots cannot be scheduled.

Schedule Data Settings:

 Specify the schedule data settings as follows:

● Select the general data backup settings:

- Backup Type

- Destination Type

- Backup Prefix

- Backup Destination

● Specify the proper schedule data settings:

- Schedule Name

- Start of Schedule

- Recurrence pattern

- Execution time (in UTC time)

Note :

To transition from SAP HANA 1.0 to SAP HANA 2.0, note the following:

● Backup schedules created with SAP HANA cockpit 1.0 are not compatible with SAP HANA cockpit 2.0.

● Before you upgrade from SAP HANA 1.0 to SAP HANA 2.0, use the SAP HANA cockpit 1.0 to delete all the backup schedules created with SAP HANA 1.0.

● After you upgrade to SAP HANA 2.0, create new backup schedules.


Enable the Job Scheduler

The XS job scheduler has to be activated for the system database and each tenant database.A backup of a tenant database must be scheduled through the tenant database itself. A backup of a tenant database cannot be scheduled through the system database.

For the system database, the XS scheduler must be enabled in the nameserver.ini file. To enable the XS scheduler, you can use the following SQL statement:.

 



Scheduling the jobs using DBACOCKPIT

 


To start the DBA Cockpit, use transaction code DBACOCKPIT.

Performing Scheduling

To schedule an action, proceed as follows:

1. To open the DBA Planning Calendar, in the DBA Cockpit, choose Jobs → DBA Planning Calendar .

2. To create a new action, perform one of the following:

● Double-click a calendar row.

● Select a calendar cell and choose Add.

● Move an action from the Action Pad to a calendar cell in the future. You can also move actions to reschedule them.

To copy an action, hold down the Ctrl key while dragging.

3. Specify the following action details:

● Planned Start: Specify the start date and time of the action.

● Action Parameters: If different from the default, specify the location and prefix for the file.

● Recurrence: Specify when the action will be repeated or if it will be executed only once.

 

     Multistreaming Data Backups with Third-Party Backup Tools

 


To configure the number of parallel streams, use the parallel_data_backup_backint_channels.ini file parameter (default: 1, max: 32).

During recovery, the number of streams used is the same as during backup. This is

independent of the current setting of the parameter.


                            Configuring a Log Area Backup



A log is written to Log-Buffers in-memory.

If a Log-Buffer becomes full or a commit entry is written, the Log-Buffer is written to the assigned log volume.

The log is finally written into log segments, where multiple Log-Buffers can be combined.

You can find many log files as log segments (1 GB) on the log volume.




The system can reuse the space that is occupied in the log volume by the log segments. The log_mode parameter controls how the log segments are reconsumed.

Overwrite mode is as follows: log_mode = overwrite.

Note:

The overwrite mode, log_mode = overwrite, is not recommended for production systems.With log_mode = overwrite, no point-in-time recovery is possible. For recovery, only data backups are used; the logs are not used. 


To Recover the database to a specific data backup recovery option is the only option that can be selected.


Normal mode is as follows: log_mode = normal (default). The features of normal mode are as follows:

● Keeps log segments until backup

● Automatic log backup available (time-based or when segment is full)

   Ex: 15 min or 1 GB of size

● Log backup directory configured with parameter basepath_logbackup

Note:

After installation, SAP HANA temporarily runs in overwrite log mode. After you create the first full data backup, SAP HANA automatically switches to the default normal log mode.




Note:

Backups made using third-party tools always use the destination: /usr/sap/<SID>/SYS/global/hdb/backing. Can’t be changed.

Log segments in the log area are only released for overwrite after a successful log backup. In some situations, there can be a delay in releasing log segments because they are waiting to be backed up. As a result of this delay, the log area can grow. If the log segments cannot be backed up and released faster than the log area is growing, the log area can become even more full.

 To remedy this issue, SAP HANA can write all the log segments of a service that is ready to be backed up at a particular time to a single log backup.

The maximum size of the log segments to be processed by a single backup operation is defined by the parameter max_log_backup_size in the backup section of the global.ini file. The default value is 16. This means that one backup operation creates log backups with a maximum size of 16GB.

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