KVM : Storage Migration2024/05/10

This is the example to use Storage Migration feature for Virtual Machines.

The different point of Storage Migration from the Common Live Migration is that Storage Migration does not need a Storage server that has Virtual Machine images, when executing Storage Migration, Virtual Machine image on a KVM host is migrated on another KVM host like follows.

                          Storage Migration
                        <------------------->
                        
+----------------------+                     +----------------------+
|  [   KVM Host #1  ]  |10.0.0.30   10.0.0.51|  [  KVM Host #2   ]  |
|                      +---------------------+                      |
|   kvm01.srv.world    |                     |    kvm02.srv.world   |
+----------------------+                     +----------------------+

[1]	Configure 2 KVM Host Server and Create a Virtual Machine on a KVM Host. Configure DNS or hosts to resolve names or IP addresses normally, first.
[2]	Confirm the file size of a Virtual Machine image like follows on a KVM host, and next, move to another KVM host to create an empty disk image like follows.

# show the size of Virtual machine

root@kvm01:~#

qemu-img info /var/kvm/images/ubuntu2404.img

image: /var/kvm/images/ubuntu2404.img
file format: qcow2
virtual size: 20 GiB (21474836480 bytes)
disk size: 7.65 GiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    compression type: zlib
    lazy refcounts: true
    refcount bits: 16
    corrupt: false
    extended l2: false
Child node '/file':
    filename: /var/kvm/images/ubuntu2404.img
    protocol type: file
    file length: 20 GiB (21478375424 bytes)
    disk size: 7.65 GiB

### on another KVM host ###
# create a disk which is the same size of a Virtual Machine

root@kvm02:~#

qemu-img create -f qcow2 -o preallocation=falloc /var/kvm/images/ubuntu2404.img 21474836480

[3]	That's OK, Run Storage Migration like follows.

root@kvm01:~#

virsh list

 Id   Name         State
----------------------------
 1    ubuntu2404   running

root@kvm01:~#

virsh migrate --live --copy-storage-all ubuntu2404 qemu+ssh://10.0.0.51/system

root@kvm01:~#

virsh list

 Id   Name       State
--------------------------

# VM migrated

### on another KVM host ###

root@kvm02:~#

virsh list

 Id   Name         State
----------------------------
 1    ubuntu2404   running

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