Backup Methods
There are the following methods of saving objects:
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Online backup with partial transactions
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Online backup at a transaction boundary
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Offline backup
Before deciding on a backup method, you should weigh up the advantages and disadvantages of each method.
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Advantages |
Disadvantages |
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The system is available for most operations during the backup. |
The recovery is more complex than with other backup methods, because you have to restore journal receivers and apply or remove journal changes to reach a consistent state in the database. |
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The system remains active, so buffers and cursor caches are not lost, which improves performance. |
Transactions that include DDL statements (such as ALTER TABLE) must still be at a commit boundary to allow this backup type to be completed. |
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Advantages |
Disadvantages |
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Compared to the offline backup, the system is unavailable for only a short time until the common transaction boundary is reached. |
The backup might fail if the checkpoint cannot be reached due to long-running transactions. |
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The system remains active, so buffers and cursor caches are not lost, which improves performance. |
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The backup is in a consistent state, so it is not mandatory to apply journal changes after restoring the backed-up libraries. |
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Advantages |
Disadvantages |
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Reaching the checkpoint is guaranteed, so the backup cannot fail due to long-running transactions. |
Buffers and cursor caches are cleared, so you experience slower performance for some time after starting up the system. |
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A large amount of time is needed for the save. |
Summary of Backup Methods
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An online backup with partial transactions allows you to keep the SAP system up and running while performing the backup. However, you need to back up the journal receivers as well, and to restore the database into a consistent state you must apply journal changes. This method is only available with operating system IBM i5/OS V5R3M0 or higher. We recommend this method when you expect continuous availability of the SAP server and if you are saving the journal receivers to allow recovery up to the point in time right before a potential failure.
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An online backup at a transaction boundary requires only a short time window where the SAP system is not available. The backup is in a consistent state, so it is not mandatory to apply journal changes after restoring the database. We recommend this method for systems where you do not need to save journal receivers such as test systems because recovery of the state during the backup is sufficient.
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An offline backup is suitable when enough time is available. The backup is in a consistent state, so that it is not mandatory to apply journal changes, and there is no risk that the backup may fail because of long-running transactions.