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Understanding and troubleshooting vMotion (1003734)

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Symptoms

  • vMotion fails at 10%
  • vMotion times out
  • In VirtualCenter/vCenter Server, you see errors:

    • Migration will cause the virtual machine's configuration to be modified to preserve the CPU feature requirements for it's guest operating system.
      Operation timed out
    • A general system error occurred:

      Failed waiting for data. Error 16. Invalid argument

    • A general system error occurred: failed to look up vMotion destination resource pool object

Purpose

This article provides information on troubleshooting the vMotion process.

Resolution

Introduction

When performing a live migration of a virtual machine from one ESXi host to another, vMotion consist of these steps:

vMotion request is sent to the vCenter Server

During this stage, a call is sent to vCenter Server requesting the live migration of a virtual machine to another host. This call may be issued through the VMware vSphere Web Client, VMware vSphere Client or through an API call.

vCenter Server sends the vMotion request to the destination ESXi host

During this stage, a request is sent to the destination ESXi host by vCenter Server to notify the host for an incoming vMotion. This step also validates if the host can receive a vMotion. If a vMotion is allowed on the host, the host replies to the request allowing the vMotion to continue. If the host is not configured for vMotion, the host replies to the request disallowing the vMotion, resulting in a vMotion failure.

Common issues:

vCenter Server computes the specifications of the virtual machine to migrate

During this stage, details of the virtual machine are queried to notify the source and destination hosts of the vMotion task details. This may include any Fault Tolerance settings, disk size, vMotion IP address streams, and the source and destination virtual machine configuration file locations.

Common issues during this stage are:

vCenter Server sends the vMotion request to the source ESXi host to prepare the virtual machine for migration

During this stage, a request is made to the source ESXi host by vCenter Server to notify the host for an incoming vMotion. This step validates if the host can send a vMotion. If a vMotion is allowed on the host, the host replies to the request allowing the vMotion to continue. If the host is not configured for vMotion, the host will reply to the request disallowing the vMotion, resulting in a vMotion failure.

Once the vMotion task has been validated, the configuration file for the virtual machine is placed into read-only mode and closed with a 90 second protection timer. This prevents changes to the virtual machine while the vMotion task is in progress.

Common issue during this stage are:

vCenter Server initiates the destination host virtual machine

During this stage, the destination host creates, registers and powers on a new virtual machine. The virtual machine is powered on to a state that allows the virtual machine to consume resources and prepares it to receive the virtual machine state from the source host. During this time a world ID is generated that is sent to the source host as the target virtual machine for the vMotion.

Common issues:

vCenter Server initiates the source host virtual machine

During this stage, the source host begins to migrate the memory and running state of the source virtual machine to the destination virtual machine. This information is transferred using VMkernel  ports configured for vMotion. Additional resources are allocated for the destination virtual machine and additional helper worlds are created. The memory of the source virtual machine is transferred using checkpoints.

After the memory and virtual machine state is completed, a stun of the source virtual machine occurs to copy any remaining changes that occurred during the last checkpoint copy. Once this is complete the destination virtual machine resume as the primary machine for the virtual machine that is being migrated.

Common issues:

vCenter Server switches the virtual machine's ESXi host from the source to destination

During this stage, the virtual machine is running on the destination ESXi host. vCenter Server will update to reflect this change by changing the virtual machines host and pool to the destination host. The source virtual machine is powered down and unregistered from the source host. Any resources that were in use are released back to the host.

vCenter Server completes the vMotion task

During this stage, the vMotion task is marked as complete.

Common issues during this stage are:
Note: If the issue still exists after trying the steps in this article:

Additional Information

As per ftPerl consumes 100% CPU after enabling VMware High Availability (1012871), an issue with ftPerl may cause vMotion failures at 10%. This issue is resolved in VirtualCenter 2.5 Update 5 and vCenter Server 4.0, available at VMware Downloads.

Tags

cannot-vmotion no-network-vmotion vmotion-fails-at-10%, vMotion Mechanism, Storage vMotion mechanism

See Also

Update History

06/18/2012 - Updated for 5.x. 03/13/2013 - Added additional symptom. 02/04/2014 - Added ESXi and vCenter Server 5.5 to Product Versions.

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