Adding a virtual disk to the virtual machine fails with the error: possible extent truncation

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Cannot add an existing virtual disk to the virtual machine
• Adding an existing virtual disk to the virtual machine fails
• Unable to power on the virtual machine
• You see the error:

Failed to add disk scsi0:*


• In the vmware.log file of the virtual machine, you see the error:
  
  vmx| DISK: OPEN scsi0:2 '/vmfs/volumes/uuid/VMName/VMName.vmdk' persistent R[]
vmx| DISKLIB-VMFS : VmfsExtentCommonOpen: possible extent truncation (?) realSize is 58720256, size in descriptor 83886080.
vmx| DISKLIB-VMFS : "/vmfs/volumes/uuid/VMName/VMName- flat.vmdk" : failed to open (The file specified is not a virtual disk): Size of extent in descriptor file larger than real size. Type 3

Environment

VMware ESXi 4.1.x Embedded
VMware ESX 4.1.x
VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.1
VMware ESXi 4.0.x Installable
VMware ESX 4.0.x
VMware ESXi 4.0.x Embedded
VMware ESXi 4.1.x Installable

Resolution

This issue occurs when the disk sector count in the VMDK virtual disk descriptor file is incorrect.

To correct the disk sector count:

1. Open a console session to the ESX/ESXi host. For more information, see:
   
   • Unable to connect to an ESX host using Secure Shell (SSH) (1003807)
   • Using Tech Support Mode in ESXi 4.1 and ESXi 5.x (1017910)
     
     
2. Locate the VMDK descriptor file specified in the error log. For example, /vmfs/volumes/uuid/VMName/VMName.vmdk is the vmdk file specified in the log entry:
   
   vmx| DISK: OPEN scsi0:2 '/vmfs/volumes/uuid/VMName/VMName.vmdk' persistent R[]



3. Open the VMDK descriptor file using a text editor. For more information, see Editing configuration files in VMware ESXi and ESX (1017022).
   
   
4. Locate the RW disk sector count specified in the error log. For example, 83886080 is the disk sector count identified from the following log entry:
   
   vmx| DISKLIB-VMFS : VmfsExtentCommonOpen: possible extent truncation (?) realSize is 58720256, size in descriptor 83886080.

# Extent description
RW 83886080 VMFS "VMName.vmdk"
   
   
5. Change the RW disk sector count to the real size specified in the error log. For example, 58720256 is the real size identified in the following log entry:
   
   vmx| DISKLIB-VMFS : VmfsExtentCommonOpen: possible extent truncation (?) realSize is 58720256, size in descriptor 83886080.

# Extent description
RW 58720256 VMFS "VMName.vmdk"


6. Save the changes.

Additional Information

Unable to connect to an ESX host using Secure Shell (SSH)
Editing configuration files in VMware ESXi and ESX
Using Tech Support Mode in ESXi 4.1, ESXi 5.x, and ESXi 6.x