KVM : Live Migration2021/03/10 |
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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 ] |10.0.0.21 | 10.0.0.22| [ KVM Host #2 ] |
| +----------+----------+ |
| kvm01.srv.world | | kvm02.srv.world |
+----------------------+ +----------------------+
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| [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. |
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[root@kvm01 ~]# setsebool -P virt_use_nfs on
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| [4] | On KVM Hosts, if Firewalld is running, allow ports. |
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[root@kvm01 ~]# firewall-cmd --add-service={libvirt,libvirt-tls} --permanent [root@kvm01 ~]# firewall-cmd --add-port=49152-49215/tcp --permanent [root@kvm01 ~]# firewall-cmd --reload |
| [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. |
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# edit the setting of a VM you'd like to run live migration [root@kvm01 ~]# virsh edit centos-st8
<disk type='file' device='disk'>
# add : change cache mode to [none]
<driver name='qemu' type='qcow2' cache='none'/>
<source file='/var/kvm/images2/centos-st8.img'/>
[root@kvm01 ~]# virsh start centos-st8 [root@kvm01 ~]# virsh list Id Name State ---------------------------- 1 centos-st8 running
[root@kvm01 ~]#
[root@kvm01 ~]# virsh migrate --live centos-st8 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 centos-st8 running # back to the KVM Host again like follows [root@kvm02 ~]# virsh migrate --live centos-st8 qemu+ssh://kvm01.srv.world/system virsh list Id Name State -------------------- |
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