# Reconcile guest disk mappings before converting an Azure VM from SCSI to NVMe

> What guest assumptions must be checked when a VM changes its storage-controller interface?

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260909-075-reconcile-guest-disk-mappings-before-converting-an-azure-vm-from-scsi-to-nvme/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-10T00:30:41+00:00
- Modified: 2026-09-10T00:35:08+00:00
- Last reviewed by DSE: 2026-09-09
- Resource type: Checklist
- DSE priority: Information
- Topics: Business Continuity, IT
- Reading time: 2 minutes

## What you need to know

What guest assumptions must be checked when a VM changes its storage-controller interface?

## Potentially affected

Teams preparing supported Linux or Windows Azure VMs for the documented SCSI-to-NVMe conversion.

## DSE recommendation

Record persistent disk identities and boot prerequisites before approving the controller conversion and VM deallocation.

## Article

## Source facts

Changing an Azure VM from SCSI to NVMe changes how the guest uses its disks, not the remote OS or data storage. Device enumeration changes, and Windows data-disk assignments can shift without persistent identifiers. The conversion script stops and deallocates the VM. Microsoft excludes customized VMs whose third-party software can alter boot behavior, storage or filter drivers, or disk enumeration. On v6 sizes, temporary disks start RAW rather than preformatted NTFS. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/virtual-machines/nvme-linux).

## Applicability

Confirm that the target size, OS, and installed software fit the supported conversion path. Inventory boot configuration, persistent mounts or drive assignments, and temporary-disk initialization. Check the additional preview registration requirement if the selected sizes differ in temporary-disk support.

## DSE recommendation

Record persistent disk identities and boot prerequisites before approving the controller conversion and VM deallocation. Have the application owner identify every path that depends on a disk’s current enumeration. Review the conversion script and the guest-readiness changes in a representative nonproduction VM. Treat temporary-disk formatting as a separately scoped operation with exact device identification; never apply a blanket formatting step to all newly enumerated disks.

## Verification

After the authorized conversion, inspect both the Azure controller setting and the controller visible inside the guest. Reconcile OS, data, and temporary disks with the original map and test application access. Preserve the documented return command and original size in the change record. Stop on an unexpected disk identity or boot problem before attempting broad automated repairs.

## Official references

[Microsoft Learn: Convert Linux and Windows VMs from SCSI to NVMe](https://learn.microsoft.com/en-us/azure/virtual-machines/nvme-linux). Source reviewed September 9, 2026.

## Primary reference

- Name: Convert SCSI to NVMe for Linux and Windows VMs - Azure Virtual Machines | Microsoft Learn
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/azure/virtual-machines/nvme-linux
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Reconcile guest disk mappings before converting an Azure VM from SCSI to NVMe,” DSE Security, https://update.dsesecurity.com/updates/dse-20260909-075-reconcile-guest-disk-mappings-before-converting-an-azure-vm-from-scsi-to-nvme/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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