From VMware KB-2045616

Symptoms

  • Unable to power on a virtual machine with a mounted sparse disks.
  • You see the error:
An error was received from the ESX host while powering on <vm_name>.
Cannot open the disk '/vmfs/volumes/datastore_path/vm_folder/vm_name-000001.vmdk' or one of the snapshot disks it depends on.
The system cannot find the file specified
VMware ESX cannot find the virtual disk "/vmfs/volumes/datastore_path/vm_folder/vm_name-000001.vmdk". Verify the path is valid and try again.
  • In the vmware.log file on the virtual machine, you see entries similar to:
Failed to open '/vmfs/volumes/datastore_path/vm_folder/vm_name-000001.vmdk' with flags 0xa The system cannot find the file specified (25).
Worker#1| I120: Msg_Post: Error
Worker#1| I120: [msg.disk.fileNotFound] VMware ESX cannot find the virtual disk "/vmfs/volumes/datastore_path/vm_folder/vm_name-000001.vmdk". Verify the path is valid and try again.
Worker#1| I120: [msg.disklib.FILENOTFOUND] The system cannot find the file specified

Worker#1| I120: [msg.disk.noBackEnd] Cannot open the disk '/vmfs/volumes/datastore_path/vm_folder/vm_name-000001.vmdk' or one of the snapshot disks it depends on.

Note: This article applies to twoGbMaxExtentSparse disks as created and used on ESX/ESXi 4.x and earlier hosts. Such disks are disallowed on all ESXi 5.x hosts.

Cause

This issue occurs because sparse disks are not a compatible disk format on ESXi hosts.

Resolution

To resolve this issue, convert the sparse disks to a supported format with vmkfstools and then add them to the virtual machine.

To convert sparse disks to a supported format:

  1. Log in to the ESXi/ESX host as the root user.For more information, see Using ESXi Shell in ESXi 5.0 and 5.1 (2004746) or Using Tech Support Mode in ESXi 4.1 and ESXi 5.x (1017910).
  2. Navigate to the virtual machine folder by running this command:
    cd /vmfs/volumes/datastore_name/ vm_name
  3. To verify if the virtual machine is associated with sparse disk(s), view the contents of the .vmdk file, run this command:
    cat vm_name.vmdk

    You see the output similar to:

    Disk DescriptorFile
     version=1
     CID=56ed7313
     parentCID=ffffffff
     isNativeSnapshot="no"
     createType="twoGbMaxExtentSparse"
    Extent description
     RW 4192256 SPARSE "xxxxxxxxx-s001.vmdk"
     RW 4192256 SPARSE "xxxxxxxxx-s002.vmdk"

    Note: twoGbMaxExtentSparse refers to a sparse disk with a maximum 2 GB extent size.

  4. Clone all the sparse disks to a compatible format with vmkfstools by running this command:vmkfstools -i source_file destination_file -d thin

    Note: Replace thin with thick as required. For more information, see Cloning and converting virtual machine disks with vmkfstools (1028042).

  5. When the clone process completes, remove the sparse hard disk(s) associated with the virtual machine.
  6. Add the new cloned virtual hard disks.Note: In vSphere Client, right-click the virtual machine and click Edit settings. Navigate to Hardware tab > Add > Hard Disk. Select Use an existing virtual disk. Browse to locate the new hard disk file and complete the wizard.