VMware
VMware Cloud on AWS Storage Reporting
August 19, 2025
Full Article: Storage Units within vCenter and VMware Cloud on AWS - VMware Cloud Foundation (VCF) Blog
VMware Cloud on AWS bridges on-premises and cloud, but one visible difference is how storage capacity is labeled.
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What changed?
vCenter Server still uses SI prefixes (MB, GB, TB), while the VMware Cloud Services Console has moved to IEC prefixes (MiB, GiB, TiB). -
Why the difference?
Historically, the computer industry borrowed SI terms for binary values, creating confusion:-
1TB (decimal) = 1,000,000,000,000 bytes (used by drive vendors)
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1TB (binary) = 1,099,511,627,776 bytes (used in vSphere)
This mismatch led to customers seeing less usable capacity than expected. To remove ambiguity at scale, VMware Cloud on AWS now uses IEC binary notation.
Key point:
The numbers/calculations haven’t changed (always base-2). Only the labels did. -
Summary – TiB vs. TB
The term Terabyte (TB) has changed meaning over time, creating widespread confusion:
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Early on, the computer industry borrowed SI prefixes (KB, MB, GB, TB) but applied them to binary (base-2) values.
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Hard drive vendors, however, used decimal (base-10) values with the same labels.
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Result: A “1TB” hard drive often showed up as only 931GB in an operating system.
This led to lawsuits and mixed adoption:
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Some operating systems switched to decimal SI notation.
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Others adopted the IEC binary system with new labels (KiB, MiB, GiB, TiB).
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Microsoft still uses SI prefixes but applies them to binary values.
Because vendors and OSes remain inconsistent, the differences compound significantly at scale. To eliminate ambiguity, VMware Cloud on AWS now reports capacity using IEC binary notation (e.g., TiB) when deploying vSphere clusters.
You may notice the numbers themselves have not changed. VMware has always calculated storage capacity using base-2.
Summary
Within the VMware Cloud on AWS console, all storage capacities are reported using IEC notation.
1TiB = 1,024 GiB = 1,048,576 MiB = 1,073,741,824 KiB = 1,099,511,627,776 bytes
vCenter Server continues to use SI prefixes for the same calculations.
1TB = 1,024 GB = 1,048,576 MB = 1,073,741,824 KB = 1,099,511,627,776 bytes
As of this writing, there are no plans to change vCenter as it continues to straddle the line with conflicting guest implementations. We hope this clears up why the unit label changed while the reported capacity has not.
This is a repost of an older post by Glen Sizemore from December of 2020.
VMware Cloud Foundation 9 Technical Overview
August 12, 2025
VMware Cloud Foundation (VCF) drives modernization, enhances developer productivity and delivers a highly secure and resilient private cloud platform.
VMware has published a series of short videos to provide a quick understanding of VMware Cloud Foundation at a technical level.