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RMAN Restore Performance on non-ASM Filesystems (Doc ID 1561238.1)

Last updated on FEBRUARY 14, 2019

Applies to:

Oracle Database - Enterprise Edition - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.


Using RMAN in 11g Release 2 to create clone database or restore the database can be slower when restoring to a non-ASM filesystem.  
Tests have been conducted using databases which are 100G+ and backups compressed using 'BASIC' compression.  

The test executed the duplicate command using 10gR2 and 11gR2.  
The Oracle10g duplication completed in minutes where the 11g duplication in some cases took over 2 hours.  
The expectation is the restore performance will be similar.


 Oracle Database 11g Release 2

All RMAN I/O operations with ASM files select an optimal buffer size and count based on the allocation unit (AU) size and disk count of the ASM disk group.

Additional parameters are introduced to give more fine-grained control over RMAN buffer allocations. Although these parameters are supported for all RMAN operations, they are primarily intended for use in non-ASM systems, since RMAN operations in ASM will automatically select an optimal buffer configuration.


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