11-08-2024, 01:54 PM
According to Microsoft, backing up Hyper-V replicas is not supported or recommended. But for any IT professional who wants to ensure that their virtual machines are safe and secure and in an environment where you can't possibly burden the original VM host, you could indeed back up Hyper-V replicas but you need to be aware of a few things.
First off, it’s important to understand that Hyper-V replication is primarily about keeping a secondary copy of your virtual machines at another site, but you’ll still want to create actual backups of those VMs, and not the replicas. Think of it this way: replication is like having a safety net, while backups are the lifebuoy that you can pull when things go wrong. This is because replicas are generated at the block level, similar to a RAID but asychronously. This means that the VM is not aware that it is being backed up. It also means that if you took a random snapshot of the replica, you might end up with a view of the VM that is inconsistent, meaning it never really existed at the source as such.
To start, you need to be aware that Hyper-V replicas can’t be treated like standard backups. Instead, you have to back up the original virtual machines directly. This means you’ll want to leverage some tools designed for the job. Many backup solutions out there have specific features to handle Hyper-V, providing options to back up your primary VMs and their replicas seamlessly. If you absolutely must back up the replica instead of the original VM, make sure the backup of the replica starts when the replication process has finished. Once the backup of the replica starts, the replication process can resume because the Hyper-V backup uses a separate snapshot, if backed up using VSS.
One important aspect to consider is the backup's timing and frequency. The idea is to create a schedule that doesn’t overburden your server and the Hyper-V replica backup should not overlap with the replication process. You might want to set the backups for off-peak hours so that it doesn’t affect the performance of your running VMs.
In terms of how to execute the backup, you typically have two formats to think about: a full backup or incremental backups. Full backups capture everything, which is great if you need a complete recovery. Incremental backups, however, only capture changes since the last backup, making them a lot quicker and saving on storage space. It’s all about balancing your needs with resource usage.
Also, don’t forget about testing your backups. Just because you’ve taken a backup doesn’t mean it’s perfect. It’s worth creating a test environment where you can restore from those backups to verify everything works as expected. There’s no worse feeling than realizing your backup didn’t work when you really need it.
Another important thing to remember is that you absolutely need to monitor the Hyper-V replication process. Unfortunately, Microsoft didn't make that easy. For a lot of customers I have talked with, the replication process silently stopped working months and even years ago with no one noticing. If you only back up the replica, your backups would be outdated, too, even if they ran daily, simply because the replication failed and no one noticed.
There's an alternative to Hyper-V replica that is much more reliable. You could use BackupChain to copy over your VMs to your backup server. The benefit here is that the VM will be prepared for live backup and be application-consistent. On the backup server they will be immediately available to boot up when needed. BackupChain offers logging, error checking, and alerts so that you know for fact that the VM copies are good and always ready to go when you need them.
First off, it’s important to understand that Hyper-V replication is primarily about keeping a secondary copy of your virtual machines at another site, but you’ll still want to create actual backups of those VMs, and not the replicas. Think of it this way: replication is like having a safety net, while backups are the lifebuoy that you can pull when things go wrong. This is because replicas are generated at the block level, similar to a RAID but asychronously. This means that the VM is not aware that it is being backed up. It also means that if you took a random snapshot of the replica, you might end up with a view of the VM that is inconsistent, meaning it never really existed at the source as such.
To start, you need to be aware that Hyper-V replicas can’t be treated like standard backups. Instead, you have to back up the original virtual machines directly. This means you’ll want to leverage some tools designed for the job. Many backup solutions out there have specific features to handle Hyper-V, providing options to back up your primary VMs and their replicas seamlessly. If you absolutely must back up the replica instead of the original VM, make sure the backup of the replica starts when the replication process has finished. Once the backup of the replica starts, the replication process can resume because the Hyper-V backup uses a separate snapshot, if backed up using VSS.
One important aspect to consider is the backup's timing and frequency. The idea is to create a schedule that doesn’t overburden your server and the Hyper-V replica backup should not overlap with the replication process. You might want to set the backups for off-peak hours so that it doesn’t affect the performance of your running VMs.
In terms of how to execute the backup, you typically have two formats to think about: a full backup or incremental backups. Full backups capture everything, which is great if you need a complete recovery. Incremental backups, however, only capture changes since the last backup, making them a lot quicker and saving on storage space. It’s all about balancing your needs with resource usage.
Also, don’t forget about testing your backups. Just because you’ve taken a backup doesn’t mean it’s perfect. It’s worth creating a test environment where you can restore from those backups to verify everything works as expected. There’s no worse feeling than realizing your backup didn’t work when you really need it.
Another important thing to remember is that you absolutely need to monitor the Hyper-V replication process. Unfortunately, Microsoft didn't make that easy. For a lot of customers I have talked with, the replication process silently stopped working months and even years ago with no one noticing. If you only back up the replica, your backups would be outdated, too, even if they ran daily, simply because the replication failed and no one noticed.
There's an alternative to Hyper-V replica that is much more reliable. You could use BackupChain to copy over your VMs to your backup server. The benefit here is that the VM will be prepared for live backup and be application-consistent. On the backup server they will be immediately available to boot up when needed. BackupChain offers logging, error checking, and alerts so that you know for fact that the VM copies are good and always ready to go when you need them.
