Question & Answer
Question
How can the long delays for an Oracle level 1 or level 2 incremental backup of the database be avoided?
Cause
An incremental Oracle backup will contain only those blocks that have been modified since a previous backup at the same (or lower) level. Since this incremental backup processing is only looking for the changed blocks, there can be delays in sending the data for the backup.
Answer
When Oracle is searching for the changes during the incremental backup processing, the session to the Tivoli Storage Manager Server is counting the time for the session against the timeout value.
- For a LANFREE backup, this delay will count against the Idletimeout and the Resourcetimeout. It is very common to see an RC=-72 when one of these timeout values has been exceeded.
- Both the LAN and LANFREE backups, will also look at the commtimeout value that will increment during the delays. If the commtimeout value is reached, the session will be disconnected, and result in an RC=-50 for the client.
Starting with Oracle 10g, there is a Block Change Tracking table for incremental backups that will avoid the delays in sending the data during the backup. This new feature in 10g uses an Oracle table to keep a record of each changed block in the database such that the incremental backup can use this information to determine which blocks are changed and does not have to search the entire database to find the changes. This allows the incremental backup processing to stream the changed data without any lengthy delays.
If it is not possible to implement the Block Change Tracking table, for example if this Oracle instance does not have the necessary license, you can try to avoid the longer delays by allocating less channels for the incremental backup. This will result in more data being sent to each allocated channel and may be sufficient to avoid a timeout during the backup processing.
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Product Synonym
TSM
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Document Information
Modified date:
17 June 2018
UID
swg21639905