KVM : Live Migration2023/02/28 |
This is the example to use Live Migration feature for Virtual Machines.
It requires 2 KVM host server and also a storage server like follows.
Configure DNS or hosts to resolve names or IP addresses normally, first. +----------------------+ | [ NFS Servver ] | | nfs.srv.world | | | +-----------+----------+ |10.0.0.35 | +----------------------+ | +----------------------+ | [ KVM Host #1 ] |10.0.0.30 | 10.0.0.51| [ KVM Host #2 ] | | +----------+----------+ | | kvm01.srv.world | | kvm02.srv.world | +----------------------+ +----------------------+ |
[1] |
Configure Storage server that virtual machine images are placed.
For Storage server, it's OK to use NFS, iSCSI, GlusterFS and so on. It uses NFS on this example. |
[2] |
Configure 2 KVM host server and mount a directory provided from Storage server on the same mount point on both KVM server.
It uses [/var/kvm/images] for mount point on this example.
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[3] | On KVM Hosts, if SELinux is enabled and also uses NFS shared directory, change rules like follows. |
[root@kvm01 ~]# setsebool -P virt_use_nfs on
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[4] | On KVM Hosts, if Firewalld is running, allow ports. |
[root@kvm01 ~]# firewall-cmd --add-service={libvirt,libvirt-tls} [root@kvm01 ~]# firewall-cmd --add-port=49152-49215/tcp [root@kvm01 ~]# firewall-cmd --runtime-to-permanent |
[5] | Create and Start a Virtual Machine on a KVM Host and run Live Migration like follows. For connection between KVM Hosts, they connects to others with SSH, so it had better to set SSH key-pair with root account before running live migration. |
# edit the setting of a VM you'd like to run live migration [root@kvm01 ~]# virsh edit almalinux9 <disk type='file' device='disk'> # add : change cache mode to [none] <driver name='qemu' type='qcow2' cache='none'/> <source file='/var/kvm/images/almalinux9.img'/>[root@kvm01 ~]# virsh start almalinux9 [root@kvm01 ~]# virsh list Id Name State ---------------------------- 1 almalinux9 running
[root@kvm01 ~]#
[root@kvm01 ~]# virsh migrate --live almalinux9 qemu+ssh://kvm02.srv.world/system virsh list Id Name State -------------------- # just migrated
### on another KVM Host ### [root@kvm02 ~]# virsh list Id Name State ---------------------------- 1 almalinux9 running # back to the KVM Host again like follows [root@kvm02 ~]# virsh migrate --live almalinux9 qemu+ssh://kvm01.srv.world/system virsh list Id Name State -------------------- |
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