USB disks and other external disks can be used with Hyper-V in many different ways; some relate to Hyper-V backup to USB disk, some don’t:
- mounted directly as a disk inside the VM
- shared between host and guest VMs
- as host storage to hold Hyper-V VMs
- as a target Hyper-V backup drive
Mounting USB Disk to Hyper-V VMs
Often you may want to mount a USB disk directly to the VM; however, this strategy has a couple of disadvantages you need to be aware of:
- mounting a USB partition or disk into a Hyper-V VM results in the VM having complete and exclusive access; i.e., the host can no longer access the drive
- Hyper-V backups needs to be done from inside the virtual machine because the host can no longer control the disk
- In a cluster shared volume set up where one fail-over node has physical access to the disk, the VM can no longer migrate without losing access to the disk (the VM now depends on being attached to a physical node)
USB drives may be attached to the VM directly in the hopes of gaining a speed advantage; however, the speed advantage is generally low, about 5% or less compared to a fixed-sized VHDX created on the same disk instead.
Instructions: In order to mount the USB disk to the VM, first open Disk Management on the host and take the disk drive offline by right-clicking on the disk and selecting “offline”. Then go to Hyper-V Manager, edit the VM’s settings and add a new disk. Instead of adding a new VHD, select the option ‘physical drive’ and select the USB disk you took offline.
Shared Access to USB Drive Between Host and VMs
The easiest way to share access to USB drives between VMs and the host server is to simply attach the drive to the host and then create a network share, as you would do to share the drive with other computers on the network. That way the host has full access to the disk and the VM has full file access, too. The only disadvantage here is that the VM has no full disk access, since it’s using a network share and this may be an issue for programs that require physical disk access.
Using USB as a Storage for Hyper-V VMs
Smaller businesses find it extremely useful to store their VMs on USB drives. Often the server may lack disk space or the IT admin may want to be able to plug in and move virtual machines to another server if need be. USB 3 drives are perfect for this purpose because of their super-fast interface. Some higher-end USB enclosures offer RAID functionality so that you would lose out on these features either.
Another way to get RAID using USB drives is to buy two drives of the same size and create fixed VHDs on them. Then mount these VHDs in Disk Management and create a software mirror RAID or stripe RAID.
Using USB drives as Hyper-V Backup Drives
Probably the most popular choice for SMBs is to use USB drives for backups and specifically for Hyper-V backups. External disks are low-cost and very fast devices, offering transfer speeds up to 150MB/sec at a cost of just 3 cents per GB.
Alternative to Running Backups inside VMs
Some older technology relies on installing backup software inside Hyper-V VMs; however, technically this is no longer necessary. Using Hyper-V granular backup you can access the VM’s file system from the host and pull files and folders as needed.
BackupChain: The All-in-One Backup Solution
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Backup Features and Typical Scenarios
NetDrive Alternative: Map FTP site to drive letter
Granular file recovery
SQL Server backup
Granular backup: File backup for VMs done by the host
Microsoft Exchange Server backup
Online backup over the internet
Hyper-V live backup: how it works
Hyper-V USB backup: pros and cons
Cluster Shared Volume considerations
Cluster Shared Volume backup
Automatic Hyper-V backup
File backup of Hyper-V VMs