Backing up Hyper-V VMs that use pass-through disks can be a bit tricky. While it’s definitely doable with the right approach, the real question is: why are you really using a pass-through disk? First, it's important to remember that when a VM is using a pass-through disk, direct access to a physical disk is involved, and it means that some of the conventional backup strategies won't work as smoothly as with VMs that operate with virtual hard disks.
The most straightforward way to back up VMs utilizing pass-through disks is to do it at the VM level. You can use a snapshot of the physical disks attached to the VM. This means you'll need to ensure your storage supports this feature. Many enterprise-level storage solutions, like SANs, allow for snapshots, which essentially "capture" the current state of the disk without taking the VM offline. Once you have the snapshot, you can copy that to a secure location for your backup. However this is not the good way of doing it because the VM itself must prepare its file systems (part of which is on the pass-through disk). Hence, the safest way to back these VMs up is to install backup software inside the VM.
Now, there’s also the option of shutting down the VM for the backup process, basically an offline backup solution. I know, stopping the VM can be a hassle, especially in a production environment, but it’s one of the safest ways. When the VM is powered off, you can ensure data consistency on the pass-through disks, making it easier to create a backup. You’d simply make a copy of the physical disk(s) that were connected to your VM. Just be sure to document the state of the VM and the disks so that everything remains in check.
Another thing to consider is using backup software that specifically supports Hyper-V environments. Some software solutions can back up VMs with pass-through disks by interacting with the storage hardware directly. This typically involves integrating with your storage system’s APIs. If you choose this route, make sure to check that your backup tool is compatible with the Hyper-V version you're using and supports pass-through disks.
Before starting any backup, you'll want to assess the critical data you need to secure. For instance, if your VM is part of a cluster or relies on other services, think about the implications of your backup plan. It might help to have a clear understanding of the relationships and dependencies within your environment.
Once your backups are configured, regular testing is essential. You want to ensure you can easily restore from those backups when necessary. Spin up a test environment and run through the restore process. This spares you from any unpleasant surprises when you're in a real recovery situation.
Lastly, keep in mind the overall strategy. Having backups is crucial, but knowing how they fit into your wider disaster recovery plan is just as important. Whether it’s offsite storage, cloud backups, or even a separate physical location, diversifying your backup strategy can provide better resilience against data loss.
Perhaps the best thing to do is not to use pass-through disks in the first place as they block many of the benefits of virtualization, such as portability. Many users believe that using pass-through disks will lead to a performance gain, but in reality the gain is negligible. You could use a pre-allocated VHDX, for example, without sacrificing any VM features, or simply use NVMe or SSD drives with classic, dynamically growing VHDs.
The most straightforward way to back up VMs utilizing pass-through disks is to do it at the VM level. You can use a snapshot of the physical disks attached to the VM. This means you'll need to ensure your storage supports this feature. Many enterprise-level storage solutions, like SANs, allow for snapshots, which essentially "capture" the current state of the disk without taking the VM offline. Once you have the snapshot, you can copy that to a secure location for your backup. However this is not the good way of doing it because the VM itself must prepare its file systems (part of which is on the pass-through disk). Hence, the safest way to back these VMs up is to install backup software inside the VM.
Now, there’s also the option of shutting down the VM for the backup process, basically an offline backup solution. I know, stopping the VM can be a hassle, especially in a production environment, but it’s one of the safest ways. When the VM is powered off, you can ensure data consistency on the pass-through disks, making it easier to create a backup. You’d simply make a copy of the physical disk(s) that were connected to your VM. Just be sure to document the state of the VM and the disks so that everything remains in check.
Another thing to consider is using backup software that specifically supports Hyper-V environments. Some software solutions can back up VMs with pass-through disks by interacting with the storage hardware directly. This typically involves integrating with your storage system’s APIs. If you choose this route, make sure to check that your backup tool is compatible with the Hyper-V version you're using and supports pass-through disks.
Before starting any backup, you'll want to assess the critical data you need to secure. For instance, if your VM is part of a cluster or relies on other services, think about the implications of your backup plan. It might help to have a clear understanding of the relationships and dependencies within your environment.
Once your backups are configured, regular testing is essential. You want to ensure you can easily restore from those backups when necessary. Spin up a test environment and run through the restore process. This spares you from any unpleasant surprises when you're in a real recovery situation.
Lastly, keep in mind the overall strategy. Having backups is crucial, but knowing how they fit into your wider disaster recovery plan is just as important. Whether it’s offsite storage, cloud backups, or even a separate physical location, diversifying your backup strategy can provide better resilience against data loss.
Perhaps the best thing to do is not to use pass-through disks in the first place as they block many of the benefits of virtualization, such as portability. Many users believe that using pass-through disks will lead to a performance gain, but in reality the gain is negligible. You could use a pre-allocated VHDX, for example, without sacrificing any VM features, or simply use NVMe or SSD drives with classic, dynamically growing VHDs.
