Actual Imbalance (%) measures the difference in space allocated to the fullest and emptiest disks in the disk group. Comparison is in percent full since ASM tries to keep all disks equally full as a percent of their size. The imbalance is relative to the space allocated not the space available. An imbalance of a couple percent is reasonable.
The rest of the information in this section is only valid for this metric when it appears in either the Enterprise Manager Grid Control or the Enterprise Manager Database Control (if applicable).
The following table shows how often the metric's value is collected.
|
Target Version |
Collection Frequency |
|
10.1.0.x; 10.2.0.x; 11.1.0.x; 11.2.0.x |
Every 15 Minutes |
Actual Imbalance (%) is calculated as:
100 * (max((total_mb - free_mb) / total_mb) - min((total_mb - free_mb) / total_mb)) / max((total_mb - free_mb) / total_mb) where total_mb and free_mb are columns in V$ASM_DISK_STAT.
An imbalance of more than a couple percent may signal the need to initiate a manual rebalance of the disk group.
Related Topics
About Alerts
About the Metric Detail Page
Editing Thresholds
Understanding Line Charts
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