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How do I migrate a running 2.5.x virtual machine to ESX 3.x?


Production virtual machines on ESX 2.5.x need to be VMotioned to ESX 3.x. What steps are required?


Virtual machines running on ESX 2.5.x can use DMotion to VMotion and upgrade to ESX 3.0.1. The following information describes steps to perform this.
Note: This article applies to VMDK disks as well as RDM.
Note: As of ESX 3.0.1, cold migration of an RDM results in creation of a virtual disk flat file, not an RDM. For cold migrations create a new RDM on the destination 3.0.1 host pointing to the raw LUN.

DMotion: Live migration of a running virtual machine from ESX 2.5.x to ESX 3.0.1.


This requires ESX 3.0.1 and VirtualCenter 2.0.1. Both the ESX 2.5.x and the ESX 3.0.1 hosts need access to the same LUNs, the VMFS2 volume with the original RDM, the VMFS3 volume for the destination and the raw LUN.


  1. While the ESX 2.5.x virtual machine is powered on, use the VI Client (VIC) logged in to the VirtualCenter 2.0.1 server managing both the ESX 2 and ESX 3 hosts.
  2. Select the original virtual machine in the inventory. 
  3. Click Migrate to New Host in the Commands window or right-click the virtual machine and choose Migrate.
  4. Follow the Migrate Virtual Machine Wizard to select the ESX 3.0.1 host and VMFS3 datastore destination. The Wizard validates the destination and moves the configuration files of the virtual machine and virtual disks to the new VMFS3 datastore.
  5. Click Finish to start the migration. 
  6. After the virtual machine is migrated to the new host the original the ESX 2 configuration files no longer exist on the source host but the source RDM may still exist on the source VMFS2 volume. Remove the RDM by deleting the RDM from the VMFS2 datastore. The LUN continues to show as a formatted volume when viewed in the Storage Management view of the ESX 2.5.x MUI. 

    Do not remove the volume using the MUI or the data on the LUN is destroyed and the LUN returns to available Free Space. The LUN is then be available on ESX 2.5.x to be used as a new volume or RDM. After the migration the raw LUN must be unpresented to the original source host to prevent destruction from the ESX 2 host. After migration to ESX 3.0.1 this virtual machine can not be powered up on an ESX 2 host.


The destination RDM files use the following naming conventions:

  • DMotion-scsi0:00_<vmname>.vmdk  = the RDM / virtual disk descriptor file
  • DMotion-scsi0:00_<vmname>-rdm.vmdk = the RDM if the original used Virtual Compatibility mode
  • DMotion-scsi0:00_<vmname>-rdmp.vmdk = the RDM if the original used Physical Compatibility mode


To take advantage of new features in VI3:
  1. After the virtual machine is migrated it upgrade the virtual hardware while the virtual machine is powered off.
  2. VMware Tools also needs to be upgraded to the VI3 version. The tools installer requires rebooting the virtual machine to complete the upgrade. It is possible the virtual machine may fail to automatically reboot after the install so it may be necessary to manually power on the first time. During the tools install there may be a warning about previous generation hardware that is no longer used. This is normal. These steps are not required immediately after the migration but must performed as soon as possible.


  • Make sure the source virtual machine's virtual CD or floppy are not connected to physical media or image files. Use the MUI or Remote Console to switch the virtual devices to the service console device /dev/cdrom or/dev/fd0 and configure as disconnected. Also configure the virtual machine using the VI Client to make sure VirtualCenter 2.0.1 does not perceive the media to be connected.

  • Close all ESX 2 Remote Console window connections to the virtual machine. The Console tab in the VI Client may be open while the virtual machine is migrated. It momentarily goes black at the end of the migration but resumes on the new host. RC connections cause the migration to not show the status as Completed.

  • A Compatibility warning may be presented by the Wizard indicating a difference in the VMotion interface. This is safe to ignore.

    Based on VMware KB 2874895

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