You can use vSphere vMotion to migrate virtual machines to a different compute resource and storage simultaneously. Unlike vSphere Storage vMotion, which requires a single host to have access to both the source and destination datastore, you can migrate virtual machines across storage accessibility boundaries.
vSphere vMotion does not require environments with shared storage. This is useful for performing cross-cluster migrations, when the target cluster machines might not have access to the storage of the source cluster. Processes that are working on the virtual machine continue to run during the migration with vSphere vMotion.
You can use vSphere vMotion to migrate virtual machines across vCenter Server instances.
You can place the virtual machine and all its disks in a single location or select separate locations for the virtual machine configuration file and each virtual disk. In addition, you can change virtual disks from thick-provisioned to thin-provisioned or from thin-provisioned to thick-provisioned. For virtual compatibility mode RDMs, you can migrate the mapping file or convert from RDM to VMDK.
vSphere vMotion without shared storage is useful for virtual infrastructure administration tasks similar to vSphere vMotion with shared storage or vSphere Storage vMotion tasks.
- Host maintenance. You can move virtual machines from a host to allow maintenance of the host.
- Storage maintenance and reconfiguration. You can move virtual machines from a storage device to allow maintenance or reconfiguration of the storage device without virtual machine downtime.
- Storage load redistribution. You can manually redistribute virtual machines or virtual disks to different storage volumes to balance capacity or improve performance.
Requirements and Limitations for vMotion Without Shared Storage
If you want to migrate a virtual machine with vMotion in the absence of shared storage, the virtual machine and its host must meet resource and configuration requirements for the virtual machine files and disks.
vMotion in an environment without shared storage is subject to the following requirements and limitations:
- The hosts must be licensed for vMotion.
- The hosts must be running ESXi 5.1 or later.
- The hosts must meet the networking requirement for vMotion. See What Are the vSphere vMotion Networking Requirements.
- The virtual machines must be properly configured for vMotion. See Virtual Machine Conditions and Limitations for vSphere vMotion
- Virtual machine disks must be in persistent mode or be raw device mappings (RDMs). See Storage vMotion Requirements and Limitations.
- The destination host must have access to the destination storage.
- When you move a virtual machine with RDMs and do not convert those RDMs to VMDKs, the destination host must have access to the RDM LUNs.
- Consider the limits for simultaneous migrations when you perform a vMotion migration without shared storage. This type of vMotion counts against the limits for both vMotion and Storage vMotion, so it consumes both a network resource and 16 datastore resources. See vCenter Server Limits on Simultaneous Migrations.
When you migrate a powered-on virtual machine with vMotion in the absence of shared storage, the migration goes over the network using the vMotion vmknic, and the data is transferred directly between the two ESXi hosts.
