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The ARBn background process starts the rebalance process automatically when you delete or insert a disk from the ASM disk groups. This process is completed in a much shorter time when you do it in parallel.
If no power limit is specified in Disk drop or add operation, it will perform operations according to asm_power_limit parameter.
We can see rebalance from the v$asm_operation (gv$asm_operation for RAC) view.
You can see the parallellism value in the POWER column.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | SQL> select INST_ID, OPERATION, STATE, POWER, SOFAR, EST_WORK, EST_RATE, EST_MINUTES from GV$ASM_OPERATION; INST_ID OPERA STAT POWER SOFAR EST_WORK EST_RATE EST_MINUTES ---------- ----- ---- ---------- ---------- ---------- ---------- ----------- 7 REBAL WAIT 1 8 REBAL RUN 1 360450 360485 4840 30 2 REBAL WAIT 1 1 REBAL WAIT 1 3 REBAL WAIT 1 6 REBAL WAIT 1 5 REBAL WAIT 1 4 REBAL WAIT 1 8 rows selected. |
When we increase the power limit value of the related disk group as follows, the operations will be completed in a shorter time.
1 2 3 | SQL> ALTER DISKGROUP DATA REBALANCE POWER 15; Diskgroup altered. |
When we query again;
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | SQL> select INST_ID, OPERATION, STATE, POWER, SOFAR, EST_WORK, EST_RATE, EST_MINUTES from GV$ASM_OPERATION where GROUP_NUMBER=1; INST_ID OPERA STAT POWER SOFAR EST_WORK EST_RATE EST_MINUTES ---------- ----- ---- ---------- ---------- ---------- ---------- ----------- 8 REBAL WAIT 15 3 REBAL WAIT 15 4 REBAL WAIT 15 2 REBAL WAIT 15 6 REBAL WAIT 15 5 REBAL WAIT 15 1 REBAL RUN 15 1110 8281 1897 3 7 REBAL WAIT 15 8 rows selected. |
