What is meant by the numbers for ASM balance metric thresholds? (4268795)

The metrics are a single percentage value that indicates how well balanced the cluster is. A value of 100% indicates that all disks in the ASM disk group are performing the same amount of I/O, a value of 0% indicates that one disk is performing all the I/O for the ASM group.

Like if there are 3 disks, ideally each should perform 33.3% of the I/O work, but the actually I/O work is 20%,20%,60% , then Spotlight will calculate the balance as: 100%- [Abs(33.3%-20%)+Abs(33.3%-20%)+Abs(33.3%-60%)] = 47% -- this is the threshold.

Each disk’s actually work is calculated from a list of I/O values (called samples, >20), they are fetched from v$asm_disk and v$asm_diskgroup.