Avamar: Image Backup completes, but fails with avvcbimage Error <14621>: Invalid Chunk-Mode HTTP content was returned from datacenter

 avvcbimage Error <14621>: Invalid Chunk-Mode HTTP content was returned from datacenter

Image Backup and Proxy Usage

During the process of image backup, the proxy leverages vCenter’s HTTP access (accessible using url https://<vcenter.example.com/folder>) to perform several critical tasks:

1. Inspection of Datacenter, Datastore, and Virtual Machine Folders:

   • The proxy interacts with the vCenter server to examine the structure of the data center, available datastores, and virtual machine (VM) folders. This inspection helps identify the relevant VMs and their associated files.
   • By analyzing the folder hierarchy, the proxy ensures that it captures the necessary data for successful backups.

2. Downloading VMX and NVRAM Files:

   • The VMX file contains essential configuration details for a virtual machine, including hardware settings, resource allocations, and virtual hardware configuration.
   • The NVRAM file stores the VM’s BIOS or UEFI settings.
   • The proxy retrieves these files using the vCenter’s HTTP access to ensure accurate backup and restoration.

Chunked Transfer Encoding in HTTP

In the context of HTTP, chunked transfer encoding is a mechanism used for transmitting data in a series of smaller chunks. Instead of sending the entire payload at once, the server breaks it down into manageable pieces. Each chunk includes both the data and its size. However, if an error is encountered stating "Invalid Chunk-Mode HTTP content," it indicates that the data was not transmitted in the expected format. Possible reasons for this issue include incorrect chunk sizes, missing or malformed chunks, or other irregularities in the data stream.

Option 1: Disable Datastore Information Download:

• Open the file /usr/local/avamarclient/var/avvcbimageAll.cmd on the proxy server.
• Locate the following entry:

  # If true, proxy will download datastore information by curl or gSoap from vCenter, if false, only VMX and NVRAM files are download.
  # Default is true
  # --download_datastore_info=true
  

• Modify it as follows:

  --download_datastore_info=false
  

• This change ensures that the backup excludes datastore information from vCenter, focusing only on VMX and NVRAM files.

Option 2: Downgrade the Error Message:

• Edit the file, /usr/local/avamarclient/var/avvcbimageAll.cmd, on the proxy server.
• Add the following flag:

  --downgrade-error-codes=14621
  

• By doing this, the specific error with code <14621> related to "Invalid Chunk-Mode HTTP content" is converted from an Error to a Warning.

Remember to save all changes to the /usr/local/avamarclient/var/avvcbimageAll.cmd after finalizing the selected modifications.