VM 'Used' storage much larger than actual disks size.
Article ID: 391395
Updated On:
Products
Issue/Introduction
Concerns regarding the storage utilization showing larger than the actual disk size.
For example: A Virtual machine (Windows Server 2019) in a vXRail environment is displaying 20.32TB used in vsphere, despite having only 7.5TB of thin provisioned storage across three disk (60GB, 7TB, 500GB). The virtual machine was migrated from another environment. However vsphere continues to report excessive storage usage.
Storage policy - RAID 5 with FTT=1 in a Stretch Cluster
Resolution
The increased storage usage is due to the inherent nature of RAID5 with FTT=1 and the stretch cluster setup, where data and parity must be replicated across sites, effectively increasing the total storage consumption.
For every 1TB of data, It will consume 1.33TB of physical storage.
Total Storage Consumption in a Stretch Cluster:
Total Space Required = 1.33 TB × 2 = 2.66TB
Thus, for every 1TB of data, a stretch vSAN cluster with RAID 5 (FTT=1) consumes approximately 2.66TB of total storage space.
Capacity Comparison:
To provide some context, here's a general comparison of storage requirements at different RAID levels for stretch cluster:
Additional Information
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