Migrate VM Storage from Host-Local Storage to Persistent Volume

This guide provides step-by-step instructions for migrating a virtual machine storage from host-local storage to a persistent block storage volume in Private Cloud Director.

Prerequisites

• The VM for which the storage is being migrated must be in stopped state before the migration.

• Ensure that the target volume storage backend is configured and available.

• The OpenStack CLI must be installed and configured.

• Sufficient storage capacity in the block storage backend.

Steps to Migrate VM Storage

Step 1: Identify the VM and its Local Disk

List all VMs to find the target VM's ID:

Bash

openstack server list

Get the details of the specific VM:

Bash

openstack server show <VM_ID

The disk location will be under the OS-EXT-SRV-ATTR:root_device name field, typically /dev/vda or similar.

Step 2: Create a New Volume

Create a new volume of the required size to migrate the local disk.

Bash

openstack volume create --size <SIZE_IN_GB> --bootable --availability-zone <AZ> <NEW_VOLUME_NAME>

Verify the volume creation:

Bash

openstack volume show <NEW_VOLUME_ID>

Step 3: Convert the Local Disk to an Image

Stop the VM if it's running:

Bash

openstack server stop <VM_ID>

Create an image from the local storage disk of the VM:

Bash

openstack image create --disk-format qcow2 --container-format bare --file /var/lib/nova/instances/<VM_ID>/disk <IMAGE_NAME>

Verify that the image is successfully created:

Bash

openstack image list | grep <IMAGE_NAME>

Step 4: Create a New Bootable Volume from the Image

Use the newly created image to create a bootable volume:

Bash

openstack volume create --size <SIZE_IN_GB> --image <IMAGE_NAME> --bootable <NEW_VOLUME_NAME>

Ensure the volume is available before proceeding:

Bash

openstack volume show <NEW_VOLUME_ID>

Step 5: Detach Local Storage and Attach New Volume

Detach the local storage disk.

Bash

openstack server stop <VM_ID>
openstack server volume detach <VM_ID> <OLD_VOLUME_ID>

Attach the newly created volume.

Bash

openstack server volume attach --device /dev/vda <VM_ID> <NEW_VOLUME_ID>

Step 6: Start the VM

Bash

openstack server start <VM_ID>

Verify that the VM is running and using the new volume:

Bash

openstack server show <VM_ID>

Verification

• Confirm that the VM boots from the new volume.

• Confirm the new volume shows in-use.

• Check that the local storage is no longer in use.

• Connect to the VM and verify disk configuration

Bash

ssh <USERNAME>@<VM_IP>
sudo lsblk
df -h