Openstack VM live migration

• Openstack VM live migration can have 3 categories:

• Block live migration without shared storage

• Shared storage based live migration

• Volume backed VM live migration

Block live migration

• Block live migration does not require shared storage among nova-compute nodes

• it uses network(TCP) to copy VM disk from source host to destination host,

• it takes longer time to complete than shared storage based live migration.

• it takes longer time to complete than shared storage based live migration.

Shared storage based live migration

• GlusterFS as shared storage for nova-compute nodes

• Since VM disk is stored on shared storage, hence live migration much much more faster than block live migration.

Volume backed VM live migration

• VMs booted from volume can be also easily and quickly migrated just like shared storage based live migration since both cases VM disks are on top of shared storages.