# Separate Hyper-V startup memory from the post-start minimum

> Which memory floor applies while a Dynamic Memory VM starts and after it is running?

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260908-175-separate-hyper-v-startup-memory-from-the-post-start-minimum/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-08T18:14:16+00:00
- Modified: 2026-09-08T18:26:31+00:00
- Last reviewed by DSE: 2026-09-08
- Resource type: Guide
- DSE priority: Information
- Topics: IT, Networks & Infrastructure
- Reading time: 1 minutes

## What you need to know

Which memory floor applies while a Dynamic Memory VM starts and after it is running?

## Potentially affected

Administrators configuring Hyper-V Dynamic Memory for supported guest workloads.

## DSE recommendation

Ask the workload owner to define both a successful restart and acceptable steady-state operation.

## Article

## Source facts

Microsoft distinguishes the memory allocated at startup from the minimum allocation used after startup. The post-start minimum permits Hyper-V to reclaim memory that is no longer needed after the guest’s startup phase. Hyper-V also monitors the host operating system’s runtime health when deciding how much memory it can safely allocate to VMs. [Microsoft documentation](https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/dynamic-memory).

## Applicability

Identify the guest release, application support requirements, current startup and minimum values, host memory, and expected concurrent VMs. Review all Dynamic Memory settings together before changing a single number.

## DSE recommendation

Ask the workload owner to define both a successful restart and acceptable steady-state operation. Record startup memory and the post-start minimum as separate decisions. Choose a representative application load and a restart sequence that includes the other VMs expected to be active on the host.

## Verification

Observe guest startup, application readiness, and memory allocation as the workload settles. Repeat under the approved concurrent-host load and compare results with the two memory decisions. Preserve a failed restart or unacceptable steady-state response as a finding rather than treating consolidation density as the only acceptance measure.

## Official references

[Microsoft Learn: Dynamic Memory for Hyper-V Virtual Machines](https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/dynamic-memory). Source reviewed September 8, 2026.

## Primary reference

- Name: Dynamic Memory for Hyper-V Virtual Machines
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/dynamic-memory
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Separate Hyper-V startup memory from the post-start minimum,” DSE Security, https://update.dsesecurity.com/updates/dse-20260908-175-separate-hyper-v-startup-memory-from-the-post-start-minimum/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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