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[V7] ISSUE: Fail to load CBT, will perform normal in-file delta (Hyper-V VM backup)

Article ID: 5221
Reviewed: 2017-10-06

Product Version:
AhsayOBM: - 7.13.x
OS: Windows

ATTENTION 1st January, 2022: v7 officially End-of-Life [details]

Problem Description

When performing a Hyper-V VM backup (Hyper-V 2008 R2 or newer releases) with a backup destination set to AhsayCBS, Cloud storage, or SFTP / FTP storage, the following warning message is displayed on the backup client interface, or in the backup report:

No. Type Timestamp Log
* ... ... ...
* info ... Start creating Shadow Copy Set...
* info ... Shadow Copy Set successfully created
* warn YYYY/MM/DD hh:mm:ss Fail to load CBT, will perform normal in-file delta
* ... ... ...


The CBT (Change Block Tracking) feature is only supported for Hyper-V 2008 R2 or new releases, with backup destination set to a local or network drive relative to the Hyper-V host.


To utilize the CBT (Change Block Tracking) feature for Hyper-V 2008 R2 or newer releases, re-configure the backup destination of the affected MS VM backup set to a local destination (local or network drive):

  1. Login to the AhsayOBM user interface.

  2. Select Backup Sets, then the corresponding MS Hyper-V backup set.

  3. Click on Add, then select Local / Mapped Drive / Removable Drive under the Destination storage drop down menu:

  4. Click Test to confirm if the destination is accessible, then OK and Save to confirm the changes.

    Note: Delete the previous backup destination (e.g. AhsayCBS, Cloud storage, or SFTP / FTP storage) afterward, and re-create a separate backup set that does not utilize the Hyper-V CBT feature if necessary.

    Refer to Chapter 1 in the Ahsay Online Backup Manager - Microsoft Hyper-V Guest Virtual Machine Backup & Restore Guide for details on MS Hyper-V backup set.


vm, virtual, machine, hyper-v, hyperv, hyper, cbt, block, tracking, track, infile, delta

public/5221_fail_to_load_cbt_will_perform_normal_in-file_delta_hyper_v_warning.txt · Last modified: 2021/12/16 04:39 by anna.olalia

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