Planning a backup strategy for protecting SAP Oracle databases using IBM TDP for ERP (SAP)


Planning a backup strategy itself would mean that you have finished 50% of configuration, correct planning will give you high backup and restore performance which would results in  good Return on Investment (ROI) for your company. And you should regularly check your backup strategy to make sure you are prepared for the unexpected disaster. Planning of SAP database backup should be done depending upon your SAP system landscape, network and TSM server configuration. However, you should consider these common questions before planning to protect your SAP database along with archive log files and other important operating system files.
  • Database size ?
  • Transaction rate of your database ?
  • Available LAN and LANFree network throughput ?
  • Type of events do you wish to protect your SAP system against ?
  • How fast do you need to recover from a failure ?
  • What backup windows are available ?

Points to remember before planning a backup strategy for TDP SAP for Oracle

Any common SAP system landscape generally contains Production SAP system, Development SAP system, Quality SAP system and optionally Educational SAP system. Based upon your Recovery Time Objective (RTO) and Recovery Point Objective (RPO), you should plan suitable SAP system landscape backup strategy.

1) Planning a backup strategy for SAP Oracle Database & Logs
To help prevent the loss of data associated with the Oracle databases, you should plan to back up these below mentioned Oracle files and logs on a regular basis.  For best protection, you should plan to configure daily online SAP database backups and weekly/monthly offline SAP database backups. The following files will be backed-up during online and offline SAP database backups.

Data files
Files belonging to a specific tablespace (data files) are backed up by BRBACKUP utility at the file level during offline or online backups.

Control files
The control file is backed up by BRBACKUP utility whenever a tablespace backup occurs. Oracle provides mirroring of the control file to protect the running database system against corruption of this active file. The operating system utilitites can also be used to mirror these files.

Online redo logs
Online redo logs are backed up by BRBACKUP utility whenever a full offline database backup occurs. Oracle provides mirroring of the redo log files to protect the running database system against corruption of these active files. The operating system utilities can also be used to mirror these files.

Offline redo logs
Offline redo logs are backed up by BRARCHIVE utility. You can specify that the redo logs be deleted from their original location when BRARCHIVE completes successfully.

Also Read: Integrating TDPO with RMAN to configure Oracle DB backups

2) Planning a Backup Strategy for SAP System Data
SAP system data and Oracle system data should also be backed up on a regular basis using the Tivoli Storage Manager backup-archive client incremental backup feature. Although the database is backed up with Data Protection for SAP, note that SAP, Oracle and operating system protocols are also backed up directly by the Tivoli Storage Manager backup-archive client.  You can use the BA-client to define an include-exclude list of files that to be backed up during incremental backup operation. The include-exclude list should exclude all relevant database data that has already been backed up or archived by TDP SAP for Oracle, such as data files, the control file, and online or offline redo logs. 

You can use the the example include-exclude list files which are provided in Data Protection for SAP installation directory or manually add these directories to the list of paths to be excluded in the Tivoli Storage Manager backup-archive client include-exclude list. These entries will prevent the database from being backed up twice. Following are the filesystems list which should be excluded during BA Client backup.

In UNIX or Linux
/oracle/SID/saparch/
/oracle/SID/sapdata1/
/oracle/SID/sapdata2/
/oracle/SID/sapdata3/
/oracle/SID/sapdata4/
/oracle/SID/sapdata5/
/oracle/SID/sapdata6/
...
/oracle/SID/origlogA/
/oracle/SID/origlogB/

In Windows
Assuming C:\ is the default SAP installed directory.
C:\oracle\SID\saparch\
C:\oracle\SID\sapdata1\
C:\oracle\SID\sapdata2\
C:\oracle\SID\sapdata3\
C:\oracle\SID\sapdata4\
C:\oracle\SID\sapdata5\
C:\oracle\SID\sapdata6\
...
C:\oracle\SID\origlogA\
C:\oracle\SID\origlogB\

3) Planning a Backup Strategy for Backup Protocols and Profiles
Every BRBACKUP and BRARCHIVE operation performs two actions. The first action backs up these below type of objects
  • SAP data files
  • database control files
  • online redo log files
  • offline redo log files
The second action backs up these below profile and protocol files
  • BR*Tools profile (initSID.dba)
  • BR*Tools Initialization profile (initSID.sap)
  • Data Protection for SAP profile (initSID.utl)
  • Oracle profile (initSID.ora)
  • BRBACKUP summary log (backSID.log)
  • BRARCHIVE summary log (archSID.log)
  • BRBACKUP/BRARCHIVE detailed log
  • BR*Tools main log (reorgSID.log)
  • Structure log (structSID.log)
These profiles and protocols are required by the BRTools whenever a backup, restore, or recovery is performed. If these profile and protocol files have not been backed up using a file system backup, they can only be restored using Data Protection for SAP for Oracle. These profile and protocol files are located in these directories

In UNIX or Linux
Directory                                  Files
/oracle/SID/sapreorg              BR*Tools and structure logs
/oracle/SID/sapbackup          BRBACKUP logs
/oracle/SID/saparch               BRARCHIVE logs
/oracle/SID/dbs                       Profiles

In Windows
Directory                                       Files
drive:\oracle\SID\sapreorg         BR*Tools and structure logs
drive:\oracle\SID\sapbackup     BRBACKUP logs
drive:\oracle\SID\saparch          BRARCHIVE logs
drive:\orant\database                 Profiles

Also Read: How Volume Shadow Copy Services integrates with TDP for SQL to take online DB snapshot backups

4) Planning a Backup Strategy for the Operating System
Additionally, to help prevent a complete loss of the operating system,  use operating system
utilities such as mksysb for AIX to perform system backups regularly (quarterly/half-yearly). Such backups should be performed after installing, updating, or upgrading the operating system. This will allow you to start your system from the backup medium. A configured TCP/IP environment and Tivoli Storage Manager Backup-Archive client installation should be included in a base backup in order to be able to restore all user dependent data.

Planning a backup strategy for protecting SAP databases using TDP for SAP for Oracle

5) Planning hardware for configuring backups on a SAP Database Server
In general, the production (SAP database) server is the most critical component for data transfer. You should consider the following requirements before planning to implement the backup strategy for SAP database using IBM TDP for ERP.

CPU power
Data transfer, data compression, local, or LAN-free backup operations can cause significant demands on the database server CPU. These demands are in addition to the application load caused by online backups. In many environments, the CPU is the most critical constraint. The CPU load for LAN-free backups (Managed System for SAN) can be significantly reduced by managing the Data Protection for SAP for Oracle parameter Buffer Size (BUFFSIZE).

I/O paths
Fast disk attachments with internal busses (like a peripheral component interface) and file system features like caching or reading ahead can improve data transfer rates. These attachments and features can be especially useful for backup and restore operations that contain a significant number of files and large data volumes.

Volume Mirroring settings
Operating System Volume Manager provides volume mirroring options that can significantly
reduce the data transfer rate during restore operations. As a result, not using volume mirroring options during restore operations can improve the data transfer rate.

Disk layout
The manner in which the database files are laid out can affect data transfer rates. Since Data Protection for SAP allows parallel access to database files during backup and restore operations, distribute data across several disks in order to take advantage of this feature.

Database size
The size of a database can be reduced by offloading inactive data to an external archive.

Size of the database files
When similar files are the same size, multiplexing can be used to improve data transfer rates.

Backup types
Online backups save database files, control files, and redo logs non-disruptively. On the other hand, more data is saved to redo log files during an online backup. The amount of data saved to redo logs during an online backup may be decreased when using the file-online mode provided by SAP, while such a backup will take longer. Incremental backups will reduce the backup time and the amount of data to be sent to the backup server while restore time may be increased. If you want to take SAP database incremental backups, Oracle RMAN must be configured.

6) Planning hardware for a  Backup Server (TSM server) 
Consider these items when setting up the Tivoli Storage Manager server.  Data Protection for SAP for Oracle uses the Tivoli Storage Manager archive management-class  function for all backup activities.

Dedicated backup server
A dedicated backup server allows sharing of resources and provides an efficient resource utilization.

CPU power
Observations show that for a given data throughput, the CPU load on the backup server is approximately 60% of that on the database server. Therefore, backup server CPU power is not quite as critical as the CPU power of the database server. However, demands on the Tivoli Storage Manager server CPU do increase when several clients access a single Tivoli
Storage Manager server and also if TSM deduplication is running for other normal clients. 

Storage hierarchy
Backup of large data files should be directed to tape in order to achieve the highest transfer rates. If disks must be used, it is recommended to use one disk pool per session. Small files such as log files should be directed to disk storage first and then be migrated to tape collectively to avoid excessive tape mounts.

Parallel sessions
The Tivoli Storage Manager server allows using several tape drives in parallel to store data. This can increase overall data throughput. In order to exploit this feature, the corresponding Tivoli Storage Manager node must be allowed the appropriate number of mount points and the device class must be allowed the appropriate mount limits.

Also Read: Points to remember when taking backup to multiple storagepools simultaneously

7) Planning for Tivoli Storage Manager server storage
1) Data Protection for SAP transfers data to and from the backup server through single or multiple (parallel) sessions to the Tivoli Storage Manager server. Each session must have a storage device associated with it. The SAP backup ID is persistently linked with each backup file. This backup ID can be used later to determine all files required for a complete restore.

2) In SAP terminology 'backup' means backup of data files, 'archive' (BRARCHIVE) means the backup of archived redo log files. Data Protection for SAP for Oracle uses the Tivoli Storage Manager archive function for both backup types.

3) Tape storage is the preferred media for storing the database contents as this is proven to provide the best data throughput for backup and restore. In addition, the backup file sequence is maintained for restore which improves restore processing time. 

4) A disk-tape storage hierarchy is recommended for backing up log files, each log file should be backed up immediately after it is placed in the archive directory. This provides the best protection against data loss and eliminates the need to mount a tape for small sized  files.

5) Collocation is a Tivoli Storage Manager function that ensures client data is maintained together on one tape. Collocation should be avoided for Data Protection for SAP backups when enabling parallel sessions for use with multiple tape drives in parallel. Collocation should also be avoided when using the multiple log copy function.

6) To improve availability you can use alternate TSM servers for backup and to improve performance you can use multiple TSM servers for SAP database backup.

7) Database backups are typically retained for a specified period and then become obsolete. In order to manage backup storage space efficiently, delete obsolete backups so that the tape storage space can be reclaimed. There are two ways to perform this deletion:
  • Set an appropriate archive retention period with Tivoli Storage Manager options.
  • Use the Data Protection for SAP backup version control function (MAX-Version) in initSID.utl file. When the number of backup versions  is exceeded, entire backup generations such as full backups and all related redo log backups, are automatically deleted.
8) Be aware that the SAP backup log may still list deleted (expired) backups since this log cannot be updated by Data Protection for SAP.

8) Network Settings Requirements
Consider the following network settings while planning to protect the SAP database.

Use LAN-free backup
LAN-free backup can reduce the load on the network and on the Tivoli Storage Manager server, thus improving data transfer rates. When using LAN-free backup, make sure fiber channel adapter capacity to the SAN can accommodate the data transfer rates of the disk reads and tape writes.

Network bandwidth
Experience reveals that the effective throughput capacity is approximately half of the theoretical network bandwidth. For high-speed networks (such as Gigabit Ethernet LAN), the network adapters limit the throughput rather than the network itself.

Network topology
A dedicated backbone network that is used only for backup and restore operations can improve the data transfer rate.

TCP options
Use TCP options that are the most beneficial for your environment.

Multiple Paths
Data Protection for SAP for Oracle allows you to increase the overall throughput rate to the backup server by specifying multiple network paths.

Also Read: All Tivoli Data Protection (TDP) Installation & Configuration Steps

9) Alternate or parallel backup paths and backup servers (optional)
Data Protection for SAP for Oracle can use several communication links between Tivoli Storage Manager clients in order to control alternate backup paths and alternate backup servers. This feature can increase throughput by transferring data over multiple paths simultaneously or to and from several servers in parallel. It can improve the availability of the Tivoli Storage Manager client-to-server communication and enable disaster recovery backup to a special (remote) Tivoli Storage Manager server. Each session path in the initSID.utl profile is defined by a server statement and the corresponding definitions in the Tivoli Storage Manager client system option file dsm.sys (UNIX and Linux) or server.opt (Windows).

The SERVER <server 1..n> and SESSIONS parameters defined in the Data Protection for SAP profile (initSID.utl) denotes the name of the Tivoli Storage Manager servers and number of parallel sessions that TDP SAP schedules for the given path respectively.

10) Creating multiple redo log copies
Data Protection for SAP for Oracle can save a number of copies of each redo log by using different Tivoli Storage Manager server management classes. By creating multiple redo log copies on separate physical media, the administrator can restore and recover a database even if a backup tape becomes corrupt. These parameter setting can be modified in the initSID.utl file according to your SAP & TSM server environment.

BRARCHIVEMGTCLASS denotes the Tivoli Storage Manager server management classes to be used when saving redo logs. With the use of different management classes, the backup media targeted for redo logs is separated from the backup media targeted for the database objects. Different redo log copies can also be saved to different backup media. To best protect against the loss of data, it is important that the different management classes are linked to different storage pools within Tivoli Storage Manager storage so that the various redo log copies reside on different backup media.

REDOLOG_COPIES allows the administrator to initiate the creation of multiple backup copies of each redo log. By creating multiple copies on separate physical media, the database administrator is able to restore and recover an Oracle database in an SAP environment even if a backup tape becomes corrupt or lost.

MAX_SESSIONS specifies the maximum number of sessions that a single Data Protection for SAP instance is allowed to access to the Tivoli Storage Manager server.

11) Estimating Backup and Restore performance
Configuration changes and infrastructure problems affect both backup and restore operations similarly. Therefore, modifications supporting a fast backup should also be considered as applicable to the restore operation. Generally, it is recommended to tune the backup and then run a restore test to verify that restore still works in a satisfactory manner. During a restore operation, the values of these parameters are determined by their settings during the corresponding backup

Compression
If compression is used during the backup, data needs to be decompressed during restore process.

Multiplexing
The same level of multiplexing as was used during backup is automatically applied during restore.

Multiple Servers
When a backup is performed using multiple servers, the same servers must be online and available during the restore operation.




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