VM power on fails with "Cannot open the disk" "one of the snapshot disks it depends on" due to incompatible disk type
search cancel

VM power on fails with "Cannot open the disk" "one of the snapshot disks it depends on" due to incompatible disk type

book

Article ID: 401235

calendar_today

Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

This issue can arise in environments where virtual disks are created or manipulated on platforms other than ESXi—such as Microsoft Hyper-V (VHD format), VMware Workstation, VMware Fusion, or when using third-party image conversion tools that produce an unsupported disk type for ESXi. When these disks are attached to a virtual machine on an ESXi host, the VM power-on operation may fail, sometimes due to incompatibilities with the disk’s internal format or type.

  • Virtual machine power on operation fails with error "Object type requires hosted I/O" 
  • In /vmfs/volume/datastore/vmfolder/vmware.log, you see entries similar to:

File system specific implementation of LookupAndopen[file]failed
Object type requires hosted I/O
Cannot open disk "/vmfs/volumes/639c1cf9-393906e5-####-0050560129d5/test-vm/test-vm.vmdk'" or one of the snapshot disks it depends on 
Module 'Disk' power on failed
failed to open (The specified virtual disk needs repair)

  • /var/run/log/hostd.log on ESXi host: 

YYYY-MM-DD verbose hostd[527630] [Originator@6876 sub=Vigor.Vmsvc.vm:/vmfs/volumes/639c1cf9-393906e5-####-0050560129d5/test-vm/test-vm.vmx opID=mb9s1gox-#####-auto-utl-h5:#####-78-01-01-a7-e7e2] Power On message: Object type requires hosted I/O
--> Cannot open the disk '/vmfs/volumes/639c1cf9-393906e5-####-0050560129d5/test-vm/test-vm.vmdk' or one of the snapshot disks it depends on.
--> Module 'Disk' power on failed.
--> Failed to start the virtual machine.
-->
YYYY-MM-DD info hostd[527638] [Originator@6876 sub=Vigor.Vmsvc.vm:/vmfs/volumes/639c1cf9-393906e5-94b8-0050560129d5/win/win.vmx opID=mb9s1gox-#####-auto-utl-h5:######-78-01-01-a7-e7e2] Bootstrap online state is not available (expected if VM just started or exited): Fault cause: vim.fault.GenericVmConfigFault

Cause

This issue occurs when a virtual disk (VMDK) is created or converted by VMware hosted products or third-party tools into a format unsupported by ESXi, such as `createType` parameters like `monolithicSparse`, `twoGbMaxExtentSparse`, or `hosted_multi_flat`. 

ESXi requires disk types like `thin` or `zeroedthick`, and unsupported types like `monolithicSparse` cause the VM power-on failure.

Resolution

  • Identify the problematic VMDK: From the log, the problematic disk is /vmfs/volumes/639c1cf9-393906e5-####-0050560129d5/test-vm/test-vm.vmdk.
  • Verify the disk type: SSH to your ESXi host and inspect the VMDK descriptor file
    • cat  "/vmfs/volumes/639c1cf9-393906e5-####-0050560129d5/test-vm/test-vm.vmdk" or use hexdump -C  "/vmfs/volumes/639c1cf9-393906e5-####-0050560129d5/test-vm/test-vm.vmdk"
    • Look for the createType entry. If it shows monolithicSparse, twoGbMaxExtentSparse, or hosted_multi_flat, it confirms the incompatibility. Refer Types of supported Virtual Disks on ESXi hosts
  • Convert the VMDK: Using vmkfstools: Cloning and converting virtual machine disks with vmkfstools

Additional Information

Powered by Wolken Software