Windows System Backup
Comet Backup integrates with Windows System Backup to support backing up entire system volumes as
.vhdx files using the
Choose volumes to back up, and/or choose "all critical volumes".
- You can choose a volume by its drive letter (e.g.
C:\), or by a qualified Windows volume reference for volumes without a drive letter (see the output of
fsutil volume list).
A local path must be used for spooling temporary data. Spooled temporary data will be removed once the backup job completes. The selected spool path
- must be a bare root drive, and
- must not be included as one of the selected volumes, and
- must appear to Windows as fixed, not removable - regardless of whether it is physically an internal or external drive
- You can work around this issue for a removable drive by sharing a folder on the drive, and setting its UNC path as the spool directory.
Restoring (Data drive)
Once you restore the
.vhd file with Comet, it can be mounted in Windows, or it can be browsed (e.g. in 7-Zip), or it can be attached to a virtual machine, or it can be written out to a physical volume. This will allow you to access and extract individual files and folders within the backup.
Restoring (Bootable Operating System)
If you included the OS drive in the backup, it is possible to restore the OS to a bootable state, provided some additional conditions are met:
The following method of restoring the OS requires that you included the "System Reserved" partition in the backup job; either by manually including the volume, or by choosing "All Critical Volumes" in the volume selection.
If you do not include the "System Reserved" partition in the backup job, the resulting
.vhdx is a data-only file. In that situation you may need to manually recreate an NTLDR bootloader (using the
bcdedit commands) before the machine can be booted.
If you are backing up a machine that booted via EFI, you may also need to backup and restore the EFI System Partition (ESP).
Note that Windows OS installations do specialize themselves for the current hardware, and backup images are not automatically pre-prepared for hardware independence. An operating system image may only boot on identical- or highly-similar hardware. This issue originates from the
wbadmin "Windows System Backup" technology and is not specific to Comet's implementation. You may find more information online.
Using Windows Recovery
Once you restore the
.vhdx file(s) with Comet, you can boot into either Windows Recovery or the Windows install media, and choose the "System Image Recovery" option.
It may be mandatory to keep the files in the
WindowsImageBackup subdirectory on the root drive, in order for the "System Image Recovery" GUI to find the files. "System Image Recovery" is only able to restore a system image if the backup included the "System Reserved" partition.
In this dialog, you can click the "Select a system image" option to find the
.vhdxfile, so that Windows can write it back to your physical disk.
More information is available online, including a visual walkthrough:
- Windows 10 / Server 2016: via answers.microsoft.com
- Windows Vista / Server 2008: via dell.com
Later versions of the Windows install media are able to recover vhd files of older versions of Windows, and may have better driver support. For instance, if you experience problems recovering a
.vhdfile using the Server 2008 install media, consider trying with install media from a newer version of windows.
You can use the
wbadmin start recovery or
wbadmin start sysrecovery commands to restore the OS without using the Windows "System Image Recovery" GUI.
.vhd file can be manually written out to a physical volume using
qemu-img convert -f vpc image.vhd /dev/sda) or any similar tool.
Using the hypervisor
.vhd file can be attached to a virtual machine and booted as-is.
Alternative ways of backing up Windows System Backup
Note that because
wbadmin is used, spool space is required. It may be preferable to use the "Files and Folders" backup type instead, that does not require spool space. Backing up a Windows OS installation in this way does not result in a bootable image.