Expanding a shared named disk fails, and the disk cannot be attached to virtual machines in VMware Cloud Director.

Products

• VMware Cloud Director

Issue/Introduction

Expanding a shared named disk fails with an error similar to the following:

The /var/run/log/hostd.log file shows the following entry:

YYYY-mm-ddTHH:MM:SS.xxxZ error hostd[264407] [Originator@6876 sub=Vmsvc.vm:<path to vmx> opID=vcd-<opID> user=<user>] ValidateDiskFileBacking: Virtual disks in multiwriter mode cannot be lazy zeroed.

The disk type of the shared named disk changed to lazy zeroed thick.

After the expansion failure, attaching the shared named disk to virtual machines failed with an error message similar to the following:

The operation could not be performed because the device spec is invalid. Incompatible device backing specified for device '0'.

 

 

 

Cause

In ESXi 7.0 or earlier versions, expanding an eager zeroed thick VMDK results in it being converted to lazy zeroed thick.

For more details, please refer to the following KB article:
https://knowledge.broadcom.com/external/article/324312

Since a shared VMDK requires the eager zeroed thick format, attaching the shared named disk to virtual machines fails.

Resolution

Run the vmkfstools --eagerzero command to convert the disk back to the eager zeroed thick format.

For details on the vmkfstools command, please refer to the following document:
Converting a Zeroedthick Virtual Disk to an Eagerzeroedthick Disk