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I'm an azure newbie and just trying to understand Azure better. My questions are specific to backing up Linux VMs in Azure. Please help me in understanding it better.

I read that Azure backup takes snapshots and then uploads them to the vault. I'm trying to understand how using 'Azure backup' to backup a VM is different from taking the snapshots of OS Disk and data disk of azure VM via "az vm" cli commands?

What exactly is the vault here? Is it internally implemented as a storage account with blob container or is it something similar to the Glacier in AWS?

Which is better cost wise, azure backup or osdisk snapshots?

If both the options are similar, i.e using azure backup or taking a snapshot of OS disk/Data disks. Is there an advantage of using one over the other?

Are the Snapshots of OS disk taken in Azure global in nature? Can they be accessed from any other geos?

In the azure portal, snapshots, what is "snapshot state"? Why is the snapshot state "Unattached" for me even after spinning off a VM from the snapshot disk?

Gudda Bhoota
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1 Answers1

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I'm trying to understand how using 'Azure backup' to backup a VM is different from taking the snapshots of OS Disk and data disk of azure VM via "az vm" cli commands?

Azure backup works as disaster recovery service(DRaaS). It is a managed service and more easier to use. You don't need to worried where and how the backup files are stored. If the VM is running, Azure Backup service uses the VMSnapshotLinux extension to take a point-in-time snapshot in Linux. Otherwise, the Backup service takes a snapshot of the underlying storage.

What exactly is the vault here?

A backup vault is an managed storage service that stores all the backups that have been created over time. It also contains the backup policy applied to the protected VMs.

Is it internally implemented as a storage account with blob container or is it something similar to the Glacier in AWS?

It is a managed service, it hasn't been announced how it is worked.

Which is better cost wise, azure backup or osdisk snapshots?

Azure backup has extra charge than the storage consumed charge. For more information, link below is for your reference.

Backup Pricing

Is there an advantage of using one over the other?

If you want to take a snapshot and the VM is running, we suggest you shutdown the VM first to take a clean and consistent snapshot. Azure backup service will use a extension to do it, we don't need to shutdown the VM.

Are the Snapshots of OS disk taken in Azure global in nature? Can they be accessed from any other geos?

A snapshot is a read-only blob, it can be accessed from any other geos.

In the azure portal, snapshots, what is "snapshot state"?

The 'Unattached' is the state of image/disk. It means that the disk haven't attached to any VM.

Amor
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  • Nice answer. Can we also say that the Snapshot can only be used for vms but Backup can be used for both vms and discs? – CageE Dec 07 '18 at 15:13
  • When you create a VM from the snapshot and you're done with the VM can you preserve the snapshot for future VMs? How would you "Unattach" it from the VM? – Rod Mar 08 '20 at 15:11