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Backup and Replication jobs fail with the following error: "CDeviceBase: resize is not supported. Failed to download disk"


Backup and Replication jobs fail with the following error: "CDeviceBase: resize is not supported. Failed to download disk".

The following conditions must be met:
  1. Veeam 8 Update 2 [] or later
  2. Backed up VM is running on ESXi 5.5 or later
  3. Hot Add transport mode is used
  4. VM has virtual disks with the same names attached to different SCSI controllers at the same device number, e.g. SCSI(0:0)=myVM.vmdk and SCSI(1:0)=myVM.vmdk
Important! In certain circumstances, such as when provisioned virtual disk sizes of all disks are the same, or depending on hot add sequence of attaching virtual disks, this VDDK bug can cause the job reporting success while creating an unrecoverable backup, where each backed up virtual disk includes data from the last virtual disk that was hot added.


Bug in VMware VDDK 6.0 results in VDDK attaching all virtual disks matching the description above to the same physical disk device, and then reading the data from the “winning” VMDK (the one that was attached last)


- Rename virtual disk files so that all disks belonging to the same VM have unique names.
- Change virtual device node on the disks with the same name to different SCSI device numbers, e.g. SCSI(0:0)=myVM.vmdk and SCSI(1:1)=myVM.vmdk
- Use network transport mode.

More information

Veeam Backup & Replication 8.0 Update 2b (Build version bypasses this issue.

To obtain Veeam Backup & Replication 8.0 Update 2b, please follow this link
KB ID: 2042
Product: Veeam Backup & Replication
Version: or higher
Published: 2015-06-09
Last Modified: 2020-08-13
Languages: ES
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