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KVM : Storage Migration2023/06/20

 
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  ]  |10.0.0.21   10.0.0.22|  [  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/debian12.img

image: /var/kvm/images/debian12.img
file format: qcow2
virtual size: 20 GiB (21474836480 bytes)
disk size: 6.37 GiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    compression type: zlib
    lazy refcounts: true
    refcount bits: 16
    corrupt: false
    extended l2: false

### 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/debian12.img 21474836480

[3] That's OK, Run Storage Migration like follows.
root@kvm01:~#
virsh list

 Id   Name       State
--------------------------
 1    debian12   running

root@kvm01:~#
virsh migrate --live --copy-storage-all debian12 qemu+ssh://10.0.0.22/system

root@kvm01:~#
virsh list

 Id   Name       State
--------------------------
# VM migrated
### on another KVM host ###

root@kvm02:~#
virsh list

 Id   Name       State
--------------------------
 1    debian12   running
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