Great start to build your own RAC with detailed instructions and explanations. For building 18c/19c/20c GI/RAC, this post is still helpful. After completing this lab, you should be in better position as an Oracle RAC DBA.
This article describes the detailed step by step installation of Oracle Database 12c (22.214.171.124 64-bit) GI and RAC on Linux (Oracle Linux 7.1 64-bit) using VirtualBox (5.0.10). It applies to Oracle 18c and 19c GI and RAC as well.
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Parameter ASM_POWER_LIMIT will affect the speed of rebalancing disks, and the resources consumed.
If COMPATIBLE.ASM disk group attribute is set to 126.96.36.199 or higher, then asm_power_limit value range is 0 to 1024.
If COMPATIBLE.ASM disk group attribute is set to lower than 188.8.131.52 , then asm_power_limit value range will be 0 to 11.
We can change the rebalance power either at the ASM instance level or at the individual disk group level.
Changing the value at the instance level, this will alter the power limit for any new operations, but not the existing ones.
SQL > alter system set asm_power_limit=5 scope=both;
Change the value at the disk group level, this will change an existing operation on the diskgroup involved in the current operation.
SQL> alter diskgroup diskgroup1 rebalance power 8;
The effect of the change can be viewed from v$asm_operation:
SQL> select * from gv$asm_operation;