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  • Troubleshooting
    • Cannot proceed – another task needs to finish using the Storage Vault first
    • Change of hardware causes registration dialog to appear
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    • Error “EFS-encrypted files may be unusable once restored”
    • Error “Media is write protected” backing up OneDrive with VSS
    • Error “operation not permitted” macOS
    • Error “The target path ‘X:\WindowsImageBackup’ already exists – please safely remove this direct...
    • Error backing up item exit status 3 Couldn’t create virtual device set: Unknown error 0x80770005
    • Found packs in index but not appearing on disk. Reindex needed
    • Inactive / Abandoned “Running” Jobs
    • Lost connection to local service
    • Lstat: CreateFile \\?\UNC\ backup: Access is denied.
    • Mount path conflict: Can’t mount path inside real directory
    • OneDrive error “The tag present in the reparse point buffer is invalid”
    • Out of memory
    • Shared Memory Provider: Could not open a connection to SQL Server
    • VSS Error: Device is not ready
    • VSS Error: Couldn’t take snapshot. The shadow copy provider had an unexpected error while trying ...
    • Windows Backup encountered an error when writing data to the backup target.
    • Error “Access is denied” when backing up files and folders on Windows
    • Error “local error: tls: record overflow”
    • Microsoft SQL Server backup encountered a VDI error
    • Network Connectivity Errors
    • How to Locate All EFS Encrypted Files for Windows 10 and Server
    • Couldn’t save folder details: fs.TempFile: Access is denied
    • Couldn’t save Office 365 data for account – The requested user is invalid
    • WARNING Data error (cyclic redundancy check) occurred inside byte range
    • Set-Disk : Access Denied During Disk Image Backup
    • The System State encountered a problem: exit status 0xfffffffc
    • Runtime: VirtualAlloc of xx bytes failed with errno=1455 fatal error: out of memory
    • Disk Image Backup – Checking if device is ready: DeviceIoControl: The request could not be performed
    • Checking if device xx is ready: DeviceIoControl: The request failed due to a fatal device hardware..
    • x509 Certificate has expired or is not yet valid
    • Couldn’t load tree/xyz for subdirectory: tree/xyz not present in any index
    • Optimizing snapshot: not present in any index
    • Reading subdirectories of – Open: /Files/Documents/ operation not permitted
    • file truncated (expected xxxx bytes, got 0)
    • WARNING: Node (xxxx) filename.ext’ collision at position xxxx
    • How to easily find disks with read / write errors in Windows
    • Multiple connections to a server or shared resource error
    • Application failed to start because no Qt platform plugin could be initialized
    • OneDrive The cloud operation is not supported on a read-only volume
    • Hyper-V Error: Backing up exit status 1 (skipping)
  • FAQs
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    • How to use Duplicati with eazyBackup e3 Object Storage
    • How to use rclone with eazyBackup e3 S3 Compatible Object Storage
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On this page
  • Consistency and guest additions
  • Replica VM
  • Pass-through disks

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  1. Documentation

“Microsoft Hyper-V” Backup

This Protected Item type backs up Microsoft Hyper-V virtual machines. The underlying technology is VSS and is compatible with all versions of Hyper-V running on Windows Server, including Windows Server 2016 (the latest version at the time of writing).

This backup type is only applicable when running on Windows Server. Hyper-V on Windows Desktop is not supported by this Protected item type.

eazyBackup integrates with the Hyper-V VSS writer to perform a Hyper-V backup snapshot, including support for in-VM quiescence on supported guest operating systems.

Backing up a Hyper-V virtual machine with eazyBackup includes, but is not limited to:

  • its configuration file

  • all attached virtual drives

  • the contents of memory (if the machine was running)

  • the full tree of saved checkpoints

You can select individual virtual machines for backup, or choose "All virtual machines".

Consistency and guest additions

The following information applies to all products that perform Hyper-V backup.

When backing up a guest VM, it's important to get a consistent state of the VM. There are some different ways this happens.

If the guest OS has all necessary Hyper-V integration services installed, then the host can request for the guest VM to take a VSS snapshot. The snapshot is then exposed to Hyper-V on the host for eazyBackup to back up. It shouldn't interrupt the guest OS. The VM backup is application-consistent. This is known as a "Production checkpoint".

If the host OS is running Server 2012 R2 or newer, but there are no integration services inside the guest OS, then Hyper-V will take a checkpoint of the VM; eazyBackup will back up the checkpoint; and then the checkpoint will be removed. This kind of checkpoint does not interrupt the guest OS. The VM backup is crash-consistent. This is known as a "Standard checkpoint".

  • You can also achieve this behaviour by disabling "Production checkpoints" in the Hyper-V settings for the VM.

If the host OS is older than Server 2012 R2, and there are no integration services inside the guest OS, then the VM will be paused; Windows will take a VSS snapshot of Hyper-V's files in paused state; the VM will be resumed and eazyBackup will back up from the VSS snapshot. It would cause a short interruption to the guest OS. The VM backup is crash-consistent.

  • You can also achieve this behaviour by disabling checkpoints in the Hyper-V settings for the VM.

Replica VM

The following information applies to all products that perform Hyper-V backup.

If you are using Hyper-V replication, you can back up your virtual machines from either the primary or replica host.

A backup taken on the primary VM host is application-consistent (if possible), by quiescing a VSS snapshot inside the VM guest; or crash-consistent otherwise. However, a backup taken on the secondary VM host is only ever crash-consistent, because the replica VM is not running in order for guest integration services to take a VSS snapshot.

Current versions of Hyper-V do not allow backing up a VM that is currently replicating. If a VM is found to be currently replicating at the time of backup, eazyBackup will retry the operation a few times. If you repeatedly see errors of the form The virtual machine '...' cannot start a backup operation because it is currently executing a conflicting operation. Try the backup again., and you are running backups from the replica VM host, you could consider

  • scheduling the backup job to run at a time when it's more likely that the VM replication is up-to-date; or

  • using Before / After commands in eazyBackup to temporarily stop VM replication while the backup job is running.

Pass-through disks

The following information applies to all products that perform Hyper-V backup.

Hyper-V supports passthrough disks, to attach a physical disk from the host directly into the guest VM. This unmounts it from the host OS.

Hyper-V itself does not support backing up passthrough disks (nor does it support replicating them). A Hyper-V backup of the guest machines can be taken from the host, but does not include any data from passthrough disks.

You can work around this issue by either

  • installing eazyBackup inside the guest VM, and backing up the extra data at a file level (this will use an extra Device license); or

  • changing your passthrough disks to be a real disk containing a large .vhd or .vhdx file. The "New Virtual Disk Wizard" in Hyper-V Manager has an option to convert an existing disk to a .vhd or .vhdx file.


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Last updated 11 months ago

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For more information about backing up a replica VM, see:

For more information about backing up passthrough disks in Hyper-V, see:

https://blogs.technet.microsoft.com/virtualization/2014/04/24/backup-of-a-replica-vm/
https://blogs.technet.microsoft.com/virtualization/2009/03/03/working-around-the-pass-through-limitations-of-the-hyper-v-vss-writer/
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