31591: Acronis Cyber Backup: Managing Throttling Policies When Working with Exchange

Last update: 23-12-2020

Microsoft Exchange Server uses throttling policies to manage the performance of an Exchange organization.

When an Exchange organization is created, a default throttling policy is automatically created that implicitly governs all users within that organization. An administrator may create custom policies that comply with the requirements of the Exchange organization. Then, they can be assigned to all users or specific users. An administrator may also modify the existing default policy. For more information about throttling policies, see the Microsoft TechNet article Understanding Client Throttling Policies.

If specific parameters of a throttling policy (default or custom) are set, the policy may impact Acronis software access to mailboxes. This leads to backup and recovery issues.

Unless it is restricted by a special registry value, Acronis software tries to automatically substitute this policy with the appropriate one during backup or recovery. The following information message is written to the product's log:

"Throttling policy 'PolicyName' preventing successful backup or recovery operation is set to mailbox 'MailboxName'. The policy will be temporarily overridden by policy 'NewPolicyName'."

Then, the product creates a new throttling policy and assigns it to the user under which this operation runs. After the backup or recovery finishes, the product rolls back the old policy automatically.

If the automatic substitution is restricted by the registry value, the "Throttling policy correction is disabled" message is written to the product's log. Then, one of the following happens (this is also true for situations when the policy substitution fails for some reason):

  • Mailbox backup or recovery often fails.
  • During database backup, metadata is collected to the least level of detail regardless of the Metadata collection option.


Setting a new throttling policy manually

You can manually set the appropriate throttling policy for the user under which backup or recovery operation runs to avoid the issues caused by the throttling policy that currently governs this user. This solution will ensure the backup succeeds and no policy-related messages are generated.

(!) The user under which backup or recovery operation runs is specified in What to back up > Access credentials (in a backup plan) or What to recover > Access credentials (in a recovery task).

Before setting a new policy, make sure that you have all of the appropriate permissions to work with the RPC Client Access settings (see the Client Access Server Permissions section in the Microsoft TechNet article Client Access Permissions).

To set the appropriate throttling policy:

  1. Run the Exchange Management Shell (PowerShell.exe).
  2. Run the Get-Mailbox cmdlet to find out what policy governs the user to whom you want to assign a new throttling policy:

    Get-Mailbox -Identity UserName | fl ThrottlingPolicy;

    If no policy name is shown, the user is governed by the default throttling policy and a new policy will always inherit all of its parameter values. (But the parameter values that you specify during policy creation will overwrite the inherited values.) Otherwise, the user is governed by a custom policy assigned by the administrator. In this case, you may change the existing policy rather than create a new one.

    (!) A custom policy may govern multiple users in an Exchange organization, so the final decision on whether to create a new policy or modify the existing one should be made by the administrator.

    ► To set a new throttling policy:

    1. Create a new throttling policy by running the New-ThrottlingPolicy cmdlet and setting the specified parameters:

    2. Assign the newly created policy to the user using the Set-Mailbox cmdlet, as follows:

      $policy = Get-ThrottlingPolicy <PolicyName>;
      Set-Mailbox -Identity <UserName> -ThrottlingPolicy $policy;

    ► To modify the existing custom throttling policy, use the Set-ThrottlingPolicy cmdlet, as follows:

    $policy = Get-ThrottlingPolicy <PolicyName>;
    $policy | Set-ThrottlingPolicy -RCAPercentTimeInAD $null -RCAPercentTimeInCAS $null -RCAPercentTimeInMailboxRPC $null -RCAMaxConcurrency $null;

  3. Restart the backup or recovery operation.

It is not necessary to manually roll back the old policy or revert the changed values of the custom policy since the configured policy will be used next time.

Acronis Backup 11.7/11.5: Setting the registry value

You can set a special registry value to disable the automatic policy substitution for the following reasons:

  • To avoid failures during the substitution.
  • The substitution is not recommended due to the peculiarities of the current infrastructure. For example, the infrastructure does not allow the Exchange organization settings to be changed without notifying the administrator. Or, the user is assigned a custom throttling policy that has parameter values which must always be kept.

To disable the policy substitution:

  1. Open the Windows Registry Editor (regedit.exe).
  2. Go to the HKEY_LOCAL_MACHINE\SOFTWARE\Acronis\BackupAndRecovery\ArxAgent\Settings key.
  3. Create the DisableMailboxThrottlingSetup DWORD value and set it to 1. Setting the value to 0 enables the automatic policy substitution.

More information

Overall this particular message can be safely ignored:

"Throttling policy 'PolicyName' preventing successful backup or recovery operation is set to mailbox 'MailboxName'. The policy will be temporarily overridden by policy 'NewPolicyName'."

Feel free to contact Acronis Support with the reference to this article if you have any questions or issues.