Could not attach...


How to resolve error: Could not attach to VBA


When attempting to backup a VM that is on local storage with a PHD Virtual Backup Appliance on a different host, the appliance can not attach the VM's virtual disks to create a snapshot for backup. For example, when backing up VM1 which was deployed to local storage on Host1 with a PHD Virtual Backup Appliance that is located on Host2, you would see an error similar to:

VM1: Could not attach 1728279c-025a-4472-0987-0ca0f376839c to VBA

The message contains the name of the virtual machine (VM1) the error occurred on and the UUID of the virtual disk that could not be attached.


Additional causes of this error include:

  1. Block size — The phdvba is on a vmfs that has a smaller block size than the block size of the volume where the VM is that it is backing up. Please look into this to confirm that this isn’t the case. Let us know the block sizes of the volume where the PHDVBA is, and where the VM is that it is trying to backup.
  2. The disk is either an RDM or is set to in “Independent Mode.” Please confirm that neither of these reasons is the case.
  3. The VM disk does not have a uuid, or the disk has a duplicate uuid. To check this, follow these steps:
    1. Open a web browser and enter the IP Address of the ESX Host.
    2. Click Browse objects managed by this host and enter the root credentials.
    3. Click Content, look for the name rootFolder and click its value (could be ha-folder-root or folder-root).
    4. Look for the name childType and select its value (ha-datacenter or datacenter).
    5. Look for the name vmFolder and click its value (ha-folder-vm or folder-vm).
    6. Look for the name childEntity and the value will be a list of numbers, these are the VMs. Sometimes there are names in next to the numbers sometimes there isn't. If you click a number it will list values for that VM including the VM name. You want to look for and select the VM in question.
    7. Look for config and click on its value (config).
    8. Look for the name hardware and click its value (hardware).
    9. Look for the name device and select the value that you are looking for (hard disks are in the 2000s).
    10. Look for the name backing and select the value (backing).
      m. Look for the name uuid and take note of their is a value present.
  4. Is the disk on storage that the PHDVBA can access? Appliances must be able to access the storage where virtual machine disks are located in order to perform the backup. If you have some VMs on local storage and others on shared, you will need to deploy at least one appliance that can access the local storage on the individual host. Each appliance can perform backups and restores for the VMs with the same shared resources. If you have configured your environment with multiple clusters or pools or other containers using different shared resources, you will need to deploy an appliance within each container to allow the VMs within to be backed up. Depending on the number of VMs and available resources within each pool, cluster, folder, or Datacenter, you may choose to deploy multiple appliances within each.


If these do not apply or you need assistance please open a ticket with support at

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