When disks are added to a diskgroup, the data on all the disks are spread out evenly. One of last steps in this process is to COMPACT the data and place it on the outer tracks of the disks.
This results in data being accessed faster due to the reduced seek time on the outer sectors.
When using FLASH drive this process is not required as there are no physical drives and the seek time is not relevant as when using physical DISK drives.
Tuning ASM Rebalance Operation
In oracle 11g to disable the compact phase the parameter “_disable_rebalance_compact” should be set to TRUE at the instance level.
ALTER SYSTEM SET "_disable_rebalance_compact"=TRUE;
In Oracle 12c this parameter has been deprecated but “_rebalance_compact” can be set at the diskgroup level.
ALTER DISKGROUP redo SET ATTRIBUTE '_rebalance_compact'='FALSE';
You can view the article “What is ASM rebalance compact Phase and how it can be disabled (Doc ID 1902001.1)” on the Metalink site and should open a ticket with Oracle Support to get their blessing for your system before disabling this to your system.
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