Resize and Redeploy¶

Use this runbook when a VM needs more or less compute capacity, or when symptoms point to host-level corruption and moving the VM to a new Azure node is the safer recovery step.

Prerequisites¶

Azure CLI installed and authenticated.
Maintenance approval for a disruptive action because both resize and redeploy can restart the VM.
Current VM size, desired target size, and a known-good maintenance window.
Awareness that temporary disk contents and dynamic public IP behavior must be considered before a redeploy.

When to Use¶

CPU or memory pressure shows the VM is undersized.
The desired SKU is different because licensing, premium storage, or throughput needs changed.
Guest symptoms suggest a host issue and normal reboot did not clear the fault.

Procedure¶

Decide whether the fix is capacity or host placement¶

flowchart TD
    A[Performance or stability issue] --> B{Primary cause}
    B -->|Need more or less compute| C[List valid resize targets]
    B -->|Suspected host problem| D[Redeploy]
    C --> E[Deallocate if required]
    E --> F[Resize and start]
    D --> G[Move to new node]
    F --> H[Verify]
    G --> H

export RG="rg-vm-compute"
export VM_NAME="vm-app-01"
export TARGET_SIZE="Standard_D4s_v5"

az vm list-vm-resize-options --resource-group "$RG" --name "$VM_NAME" --query "[].name" --output table

az vm deallocate --resource-group "$RG" --name "$VM_NAME"

az vm resize --resource-group "$RG" --name "$VM_NAME" --size "$TARGET_SIZE"

az vm start --resource-group "$RG" --name "$VM_NAME"

| Command | Purpose | | --- | --- | | az vm list-vm-resize-options | Lists the sizes that the current deployment can move to. | | --resource-group | Targets the right VM resource group. | | --name | Selects the VM to inspect. | | --query | Returns only the available size names. | | --output | Displays candidate sizes as a table. | | az vm deallocate | Releases the VM from its current host when the new size requires deallocation. | | az vm resize | Changes the configured VM SKU. | | --size | Selects the destination compute size. | | az vm start | Powers the resized VM back on. |

Resize example output:

power: VM running
size: Standard_D4s_v5

If the problem is host placement rather than capacity, use a separate redeploy step instead of the resize path above.

az vm redeploy --resource-group "$RG" --name "$VM_NAME"

az vm show --resource-group "$RG" --name "$VM_NAME" --show-details --query "{power:powerState,size:hardwareProfile.vmSize}" --output yaml

| Command | Purpose | | --- | --- | | az vm redeploy | Moves the VM to a new Azure node if host health is the suspected issue. | | --resource-group | Targets the VM that should move hosts. | | --name | Selects the VM to redeploy. | | az vm show | Confirms the final size and running state after redeploy. | | --show-details | Includes live power state information. | | --query | Returns only the fields needed for the post-redeploy check. | | --output | Formats the verification as YAML. |

Redeploy example output:

power: VM running
size: Standard_D2s_v5

Verification¶

Run a post-change inspection that proves Azure applied the intended size.

az vm show --resource-group "$RG" --name "$VM_NAME" --query "{provisioning:provisioningState,size:hardwareProfile.vmSize}" --output yaml

| Command | Purpose | | --- | --- | | az vm show | Reads the final VM model after the operation. | | --resource-group | Selects the resource group that contains the VM. | | --name | Selects the VM to verify after the change. | | --query | Returns only the provisioning state and size for the acceptance check. | | --output | Emits a compact YAML result. |

Accept the change only when the VM reports Succeeded and the reported size matches $TARGET_SIZE for resize work.

Rollback / Troubleshooting¶

If the desired size does not appear in az vm list-vm-resize-options, stop and choose a supported size instead of forcing the change.
If the resize fails, the VM model may show the requested size even while the workload is still running on the previous size; verify with the final az vm show output before closing the task.
If redeploy succeeds but the application still fails, the root cause is probably inside the guest or application stack rather than the Azure host.
If you lose data that was stored on the temporary disk after redeploy, that is expected behavior; restore only persistent data from managed disks or backups.