Virtual machine backup fails with Veeam at hot-add mdk

Products

• VMware vCenter Server

Issue/Introduction

• Veeam backup virtual machine with the backup mode of hot-add
• Backup fails at task of hot-add vmdk in Veeam backup proxy server which is a virtual machine too with the error messages:
  
  Preparing backup proxy <veeam-backup-proxy-server> for disk Hard disk × [hotadd]


• Virtual machine backup may be successful if run backup again

Environment

VMware vCenter Server

Cause

Veeam backup proxy server does not send request to vCenter Server to attach vmdk of virtual machine to it that causes the backup operations failed.

Resolution

1. Verify if any request to attach vmdk to Veeam backup proxy server virtual machine from it's vmware.log.
   
   For example, a successful backup operation about hot-add vmdk:
   
   In(05) vmx - HotAdd: Adding scsi-hardDisk with mode 'independent-nonpersistent' to scsi0:1
In(05) vmx - DISK: OPEN scsi0:1 '/vmfs/volumes/<datastore-uuid>/<backuped-vm-name>/<backuped-vm-name>-01. vmdk' independent-nonpersistent R[]
   
   
2. If there is no such log evidence, no APl of hot-add request from Veeam backup server is sent to vCenter Server. Engage Veeam to check this issue why no hot-add API sent to vCenter Server.