This metric shows the percentage of safely usable space used by a disk group. Usable free space of a disk group depends on the redundancy. In 10g Release 2, it uses the USABLE_FILE_MB column of the V$ASM_DISKGROUP_STAT view to indicate usable mirrored free space. This column displays the amount of free space that can be safely utilized taking mirroring into account and restores redundancy after disk failure. This column is used to determine the "Used % of Safely Usable" for a disk group.
This metric generates a warning alert if the disk group is using 90% of the safely usable space and critical warning for 100%. The threshold limit can be changed to generate an alert at different values.
The rest of the information in this section is only valid for this metric when it appears in either the Enterprise Manager Grid Control or the Enterprise Manager Database Control (if applicable).
The following table shows how often the metric's value is collected and compared against the default thresholds. The 'Consecutive Number of Occurrences Preceding Notification' column indicates the consecutive number of times the comparison against thresholds should hold TRUE before an alert is generated.
|
Target Version |
Evaluation and Collection Frequency |
Upload Frequency |
Operator |
Default Warning Threshold |
Default Critical Threshold |
Consecutive Number of Occurrences Preceding Notification |
Alert Text |
|
10.2.0.x; 11.1.0.x; 11.2.0.x |
Every 15 Minutes |
After Every Sample |
> |
75 |
90 |
1 |
Disk group %dg_name% has used %value%%% of safely usable free space (space that can be allocated while still having enough space to recover from failure group failures). |
For this metric you can set different warning and critical threshold values for each "Disk Group Name" object.
If warning or critical threshold values are currently set for any "Disk Group Name" object, those thresholds can be viewed on the Metric Detail page for this metric.
To specify or change warning or critical threshold values for each "Disk Group Name" object, use the Edit Thresholds page. See Editing Thresholds for information on accessing the Edit Thresholds page.
This metric is collected from the V$ASM_DISKGROUP_STAT view for 10g Release 2.
Used % of Safely Usable = 100 - (usable_file_mb/usable_total_mb)*100
Where usable_total_mb = total_mb - required_mirror_free_mb)/redundancy_factor
total_mb and required_mirror_free_mb are derived from the view column and redundancy factor is 1 for External Redundancy Disk Group, 2 for Normal Redundancy Disk Group, and 3 for High Redundancy Disk Group.
New disks can be added in a disk group to avoid the alerts. Go to the Disk Group general page and click Add to add a new disk to a disk group. Also, you can remove existing files from the disk group.
Related Topics
About Alerts
About the Metric Detail Page
Editing Thresholds
Understanding Line Charts
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