Chapter 6. VM Migration with XenMotion and Storage XenMotion
This chapter discusses migrating running VMs using XenMotion and Storage XenMotion and how to move a VMs Virtual Disk Image (VDI) without any VM downtime.
6.1. XenMotion and Storage XenMotion
The following sections describe the compatibility requirements and limitations of XenMotion and Storage XenMotion.
6.1.1. XenMotion
XenMotion is available in all versions of XenServer and allows you to move a running VM from one host to another host, when the VMs disks are located on storage shared by both hosts. This allows for pool maintenance features such as High Availability (HA), and Rolling Pool Upgrade (RPU) to automatically move VMs. These features allow for workload levelling, infrastructure resilience, and the upgrade of server software, without any VM downtime.
Note:
Storage can only be shared between hosts in the same pool. As a result VMs can only be migrated to hosts in the same pool.
6.1.2. Storage XenMotion
Storage XenMotion must not be used in XenDesktop deployments.
Storage XenMotion additionally allows VMs to be moved from one host to another, where the VMs are not located on storage shared between the two hosts. As a result, VMs stored on local storage can be migrated without downtime and VMs can be moved from one pool to another. This enables system administrators to:
•rebalance VMs between XenServer pools (for example from a development environment to a production environment).
•upgrade and update standalone XenServer hosts without any VM downtime.
•upgrade XenServer host hardware.
Note:
Moving a VM from one host to another preserves the VM state. The state information includes information that defines and identifies the VM as well as the historical performance metrics, such as CPU and network usage.
6.1.3. Compatibility Requirements
When migrating a VM with XenMotion or Storage XenMotion, the new VM host must meet the following compatibility requirements in order for the migration to proceed:
•XenServer Tools must be installed on each VM that you wish to migrate.
•The target host must have the same or a more recent version of XenServer installed as the source host.
•For Storage XenMotion, if the CPUs on the source host and target host are different, the target host must provide at least the entire feature set as the source host’s CPU. Consequently, it is unlikely to be possible to move a VM between, for example, AMD and Intel processors.
•For Storage XenMotion, VMs with more than one snapshot cannot be migrated.
•For Storage XenMotion, VMs with more than six attached VDIs cannot be migrated.
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