VNX: Capacity Issue and Calculations

There is a known issue in a small percentage of VNX SP Collect.XML files where the Used Capacity value is reported as greater than the actual capacity of the array itself. This issue affects the Used Capacity and Free Capacity values only. All other values are unaffected.

There is no known cause or remediation for this issue on the VNX array itself. It is associated with an undocumented and rare array configuration scenario. Re-running the collection is likely to yield the same results.

Live Optics detects this issue and apply corrections that account for the data defects in the SP Collect.XML file. This report is generated without a warning message. In rare scenarios, the issue cannot be adjusted successfully. If this occurs, the Used Capacity incorrectly displays a higher value than the Configured Capacity. In these circumstances, Live Optics adjusts the Used Capacity to equal the Configured Capacity. In these cases, the array is assumed to be fully used. A warning message displays to indicate this scenario, however, Live Optics has no further capabilities to normalize the data.

Capacity Calculations

Configured Capacity
Sum of all RAID Group capacity values. Excluding unbound, fast cache, and hot spares.

Used Capacity
Sum of Thin Pool LUNs Consumed Capacity Values + Sum of Thick Pool LUNs Consumed Capacity values.
Alternative formula: Pool consumed + RAID Group Consumed (only traditional RG LUNs)

Free Capacity
Configured Capacity - Used Capacity

Subscribed Capacity
Sum of RAID Group Capacity values + Sum of Pool LUNs User Capacity

RAID Group Free Capacity
Sum of RAID Group Free Capacity values. Excluding unbound, fast cache, and hot spares.

RAID Group Capacity
Configured Capacity - RAID Group Free Capacity value.