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Application-aware image processing/guest processing

When configuring backup and replication jobs, you can specify how to create the transactionally-consistent backup images of VMs. Two methods are available for bringing VM file system and applications into consistent state: VMware Tools/Hyper-V Integration Services quiescence or Veeam’s proprietary application-aware image processing (using Microsoft VSS or Linux scripts).

Key features of both methods are illustrated by the following table:

Feature VMware tools quiescence Hyper-V quiescence application-aware image processing
Support for consistent backup on Windows guest Yes Yes Yes
Sync driver for Linux guest Yes No No
Support for application-aware backup Limited Yes Yes
Pre-VSS preparation for specific applications (e.g. Oracle) No No Yes
Support for application log truncation (Microsoft SQL Server and Exchange Server) No No Yes
Support for scripts Yes (placed on VM guest) Yes (placed on guest) Yes (can be centrally distributed)
Error reporting Within VM guest OS Within VM guest OS Centralized, on Veeam backup server

Selecting guest processing options

When on the guest processing step of the job wizard, you are presented with the variety of options (as described in detail in the User Guide for vSphere and Hyper-V).

Note that you can use pre- and post-job scripting to automate job global settings from the Veeam Backup & Replication server itself. It is recommended to use the VM guest processing options for interaction with VMs.

To select the necessary options, refer to the table below.

VM guest OS type Linux with applications (without known user for Guest OS processing) Windows with applications (without known user for Guest OS processing) Windows with VSS-aware applications Windows (no VSS-aware applications) Linux with applications Windows / Linux (no applications)
Guest OS processing is applicable Y Y Y Y Y N
Use Hypervisor quiescence Y Y N N N N
Enable Veeam Application-Aware Image Processing N N Y N N N
Enable Veeam Application-Aware Image Processing and InGuest Scripts N N N Y Y N
Disable Veeam Application-Aware Image Processing Y Y N N N Y

For more details on the interaction check out Support - Guest Interaction.

Guest Access Credentials

Depending on the VM guest OS processing options selected (enabled or disabled application-aware image processing) and on the guest access method, you may need to supply access credentials for the guest OS, as described in the tables below.

Windows OS

Application-aware image processing (AAIP) Hypervisor quiescence Veeam via VIX/PSDirect Veeam via RPC Disabled (crash-consistent)
Membership in the local administrators group User account not needed No Yes User account not needed
Enter username as _\ Administrator_ 1(Local) or _\Administrator_ No Yes2(Only) No No
UAC can be enabled Yes Yes3(When) Yes Yes
Guest tools must be installed and up to date Yes Yes Yes No

Linux OS

Linux guest OS processing Hypervisor quiescence Veeam via SSH Disabled (crash-consistent)
Root user account No Yes No
User requires sudo rights No Yes No
Certificate-based authentication available No Yes No
Guest tools must be installed and up to date Yes Yes No


Since guest processing produces very low impact on VM performance, no special considerations on sizing are required. If you use VSS processing with hypervisor quiescence or Veeam in-guest processing, you need free space on each drive of the VM for the software VSS snapshot. Please check Microsoft requirements for more information.

File exclusions

Another operation Veeam Backup can do on guest OS level (NTFS only) is excluding certain files or folders from the backup. Alternatively, the job can be configured to include only specified files or folders in the backup. This functionality operates very similarly and shares a lot of characteristics with excluding Windows page file and deleted file blocks. It may help reduce size of the backup files or implement additional data protection strategies for specific data. Backups for which this option was enabled remain image-level and hypervisor APIs are used to retrieve VM data.

File exclusion feature uses a combination of NTFS MFT data and guest file system indexes collected by in-guest coordination process to determine which virtual disk blocks belong to the excluded files and thus should not be included in the backup.

Full file/folder paths, environment variables or file masks can be used to define exclusions. For more details on configuring exclusions and its limitations refer to the corresponding User Guide section.

Note: Generic file exclusions (defined for high level folders) are most effective. File masks exclusions require guest file system indexes, and generating indexes may put additional stress on guest VM and will increase backup time. For this reason it is recommended to avoid using file system masks, especially on fileservers with large number (thousands) of small files and use high level folder exclusions instead. When using include filters, file exclusions are created for everything else and can take significant time.


  1. Local administrator accounts other than the built-in Administrator account may not have rights to manage a server remotely, even if remote management is enabled. The remote User Account Control (UAC) LocalAccountTokenFilterPolicy registry setting must be configured on the VM guest to allow local accounts of the Administrators group other than the built-in administrator account to remotely manage the server:

    Path HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    Key LocalAccountTokenFilterPolicy
    Type REG_DWORD (32-bit)
    Value 1 = disable token filter and allow remote management by local administrative accounts
      0 (default) = enable token filter and do not allow remote management by local accounts

  2. Only this account is able to bypass the UAC prompt for launching processes with administrative privileges. If not applicable, see 3

  3. When performing application-aware image processing on Windows via VIX, UAC must be entirely disabled, unless the user account is the local administrator account (SID S-…-500). (CMD: WMIC useraccount get name, sid)  2

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