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Understanding Logical Used vs. Storage Used in VMware Metrics
Understanding Logical Used vs. Storage Used in VMware Metrics

This article clarifies the differences between Logical Used Space and Used Space for effective storage sizing in VMware.

Phi Team avatar
Written by Phi Team
Updated over a month ago

Overview

This article clarifies common questions about storage metrics in the OneIQ platform, specifically focusing on the interpretation of "Logical Used Space" and "Used Space" for VMware Virtual Machines (VMs). The guide aims to help you understand these metrics for better storage and backup sizing decisions. It’s important to note that OneIQ displays the metrics as provided by VMware using their APIs.

"Logical Used" vs. "Storage used" in VMware metrics

Logical Used Space and Used Space are two distinct metrics reported by VMware for virtual machines, and each serves different purposes in understanding storage requirements:

  1. Logical used: This metric represents the actual data written inside the virtual machine operating system, showing the logical capacity utilized without including the overhead from storage policies or physical storage requirements. It is particularly valuable for storage and backup sizing as it provides an accurate view of the VM’s data footprint. However, it is important to note that this metric is reported at the operating system level through VMware tools, and its availability may vary depending on the VM’s configuration or operating system version.

  2. Storage used: This metric represents the total physical capacity consumed by the virtual machine’s virtual disks on the datastore. It includes all overhead from the storage policies applied, such as mirroring or erasure coding. This figure is typically larger than the Logical Used Space due to additional data protection measures implemented by vSAN, which add redundancy and increase the overall physical storage requirements.

How to Access These Metrics in OneIQ

To view these metrics within OneIQ:

  1. Navigate to the Entities menu.

  2. Select VMware Virtual Machines (do not select "Virtual Machines" as this menu differs in displayed metrics).

  3. From the Section dropdown, select Storage Capacity.

  4. Download the Excel report from this section, which will display the Logical Used Space and other relevant metrics.

    Be aware that "Logical Used Space" is a VMware setting reported through VMware tools, and gaps may occur in the data for certain VMs, depending on their status.

Recommended Use of Metrics for Sizing

For Storage and Backup Sizing: Focus primarily on the "Logical Used Space" metric as it represents the actual data footprint of the VM. This approach ensures you are sizing your backup and storage solutions based on the data actively utilized by the VM, rather than including unnecessary overhead from storage policies.

Handling Data Gaps: In cases where there are missing values in the Logical Used Space metric, consider using the "Storage Used" metric as an alternative to estimate storage consumption.

Summary

Understanding the distinction between Logical Used Space and Used Space is important for making informed storage and backup sizing decisions in VMware environments. Logical Used Space offers a more precise view of the VM's data usage, as it excludes the additional requirements imposed by storage policies, making it the preferred metric for sizing purposes. However, its availability can vary depending on the virtual machine's in-guest configuration.

For further assistance, reach out through the OneIQ support portal.

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