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Veeam Backup for Cloud Solutions Potential Data Loss

KB ID: 4471
Product: Veeam Backup for AWS
Veeam Backup for Microsoft Azure
Veeam Backup for Google Cloud
Published: 2023-07-03
Last Modified: 2023-07-06
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Challenge

If, between the runs of a backup policy for a VM, a virtual disk is removed and added back to that same VM, data blocks belonging to that disk may be deleted from the backups during the retention process. This can lead to a data loss scenario.

Impacted Product Versions:

  • Veeam Backup for AWS — 6.0.0.335 | 6.1.0.25
  • Veeam Backup for Microsoft Azure — 5.0.0.579 | 5.1.0.63
  • Veeam Backup for Google Cloud — 4.0.0.1072

Solution

To address this issue, Veeam has released updated appliances which are available via the Veeam Updater component.
It is advised to install this update immediately.

This issue was resolved starting with the following build numbers:

  • Veeam Backup for AWS — 6.0.2.3 | 6.1.2.3
  • Veeam Backup for Microsoft Azure — 5.0.0.607 | 5.1.0.75
  • Veeam Backup for Google Cloud — 4.0.0.1080

If the AWS Plug-In for Veeam Backup & Replication is installed on the Veeam Backup Server, please also install the latest version of the plug-in. The Plug-In build number associated with this resolution is:

  • AWS Plug-In for Veeam Backup & Replication 12.2.6.5

Update Procedure

To update the backup appliance, follow the Update Installation procedure documented in the product's user guide:

After the backup appliance has been updated, all newly created backup chains will be unaffected by the data loss issue.

Remediation

After updating Veeam Backup for AWS or Veeam Backup for Microsoft Azure, the following remediation process must be performed for any VM that may have been affected by the data-loss-causing scenario. This procedure will force the recapture of data that may be missing from the existing backups.

Note: 

  • As Veeam Backup for Google Cloud does not utilize CBT, no remediation action is required after updating its backup appliance.
  • When CBT/CTK is disabled, the backup policy will read all data blocks from the source, but only missing data blocks will be transferred to the backup repository. Therefore, even though only changed data blocks are transferred, the duration of the policy will be similar to a full policy run.
  • This procedure will create a new restore point to capture any missing data. It does not repair existing restore points.
Remediation Procedure for Veeam Backup for AWS

This procedure entails (1) turning CBT off, (2) creating new restore points, and then (3) turning CBT back on.

  1. Turn changed block tracking off.
    1. Log in to the Veeam Backup for AWS backup appliance via SSH. (from Windows or Linux)
    2. Modify the file: /etc/veeam/awsbackup/config.ini
    3. Create the following parameter under the [COptions] section:
UseBackupCtk = “false”
AWS Config.ini Example: /etc/veeam/awsbackup/config.ini
  1. Return to the backup appliance UI and run the backup policies for those potentially affected VMs.
    Alternatively, you may wait until the policies run at their scheduled time before proceeding to the next step.

    During the policy run, Veeam Backup for AWS will identify all blocks that are not present in the existing restore points and store them in a new restore point.

    After the backup policies have run and new restore points have been created, proceed to the next step.
  2. Turn changed block tracking back on.
    1. Log in to the Veeam Backup for AWS backup appliance via SSH.
    2. Modify the file: /etc/veeam/awsbackup/config.ini
    3. Change the UseBackupCtk value to "true"
Remediation Procedure for Veeam Backup for Microsoft Azure

This procedure entails (1) turning CBT off, (2) creating new restore points, and then (3) turning CBT back on.

  1. Turn changed block tracking off.
    1. Log in to the Veeam Backup for Microsoft Azure backup appliance via SSH. (from Windows or Linux)
    2. Modify the file: /etc/veeam/azurebackup/Config.ini
    3.  Change parameter DisableVMBackupCBT to “true”
Azure Config.ini Example:  /etc/veeam/azurebackup/Config.ini
  1. Return to the backup appliance UI and run the backup policies for those potentially affected VMs.
    Alternatively you may choose to wait until the policies run on their schedule, however note that because changed block tracking is disable the jobs may take longer to complete.

    During the policy run, Veeam Backup for Microsoft Azure will identify all blocks that are not present in the existing restore points and store then in a new restore point.

    After the backup policies have run and new restore points have been created, proceed to the next step.
  2. Turn changed block tracking back on.
    1. Log in to the Veeam Backup for Microsoft Azure backup appliance via SSH.
    2. Modify the file: /etc/veeam/azurebackup/Config.ini
    3. Change the DisableVMBackupCBT to “false”

If this KB article did not resolve your issue or you need further assistance with Veeam software, please create a Veeam Support Case.

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