Quick Rollback in Veeam Backup & Replication: A New Mode for Quick Recovery of Virtual Machine Disks

  • Tutorial
Are you familiar with a situation where you needed to recover a virtual disk as quickly as possible after a virtual machine failed? In this case, you can start the standard full recovery of the virtual machine and wait until it is completely restored - in the new version of Veeam Backup & Replication v8 this can be done much faster by using the new incremental recovery mode - Quick Rollback .

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So, what can you do when you need to completely restore the disk of a virtual machine (VM): first of all, you can use instant recovery ( Instant VM Recovery), and then copy the VM data to the production. It should be noted that in this scenario, backup storage is used, which in technical specifications is usually inferior to storage located in the production network. Suppose that the main priority is the recovery speed, for which you are ready to restore the machine directly to its original state, bypassing intermediate testing. In this scenario, the new Veeam Backup & Replication v8.0 functionality may come in handy - this is the Quick Rollback option for the Full VM Restore script, which can be used when restoring a VM to its original location . This option indicates that only incremental changes on the VM disk (and not the entire disk, as in the usual case) should be rolled back.

What does this checkmark do?


Instead of restoring the entire disk, Veeam Backup & Replication will only restore the blocks that are necessary in order to return the VM to the state of the selected recovery point. The recovery time is significantly reduced, since only data blocks that have changed since the creation of the specified recovery point are copied. To identify the changed blocks, Veeam Backup uses the same Change Block Tracking (CBT) tracking technology as when creating incremental backups:
  • for VMware platform - a request is made to vSphere API
  • for the Hyper-V platform - similar information comes from a proprietary component (Veeam CBT engine)

Obtaining a list of changed blocks of a virtual disk from the moment the recovery point was created to the current state of the VM, Veeam Backup accurately determines which blocks at which point were changed and which of them should be restored to disk in order to roll back to the desired state.

It seems to be a simple functionality, but very useful in different situations. For example, one of the users said that when his virtual machine fell victim to a trojan, he decided not to waste time trying to plague the malware, but tried to recover from Quick Rollback - and it took only a few seconds to recover.

So, in the console, launch the Full VM Restore Wizard, we reach the step of choosing the Restore Mode .
By default, restoration occurs to the original location (the option Restore to the original location is selected ). In this case, the Quick Rollback option is available for selection - turn it on and proceed to the next step.

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What Veeam Backup does: turns off the original VM, if it still works, and starts to restore only the changed blocks.

Let's see how the performance changes in relation to the usual full VM recovery:

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Of the 20 GB of VMDK, 2.2 GB are effectively used. In a normal scenario with full VM recovery (example on the left), all 2.2 GB had to be restored (1 minute 8 seconds was spent). When the same machine began to be restored using Quick Rollback(example on the right), it took only 29 MB to recover (it took 12 seconds).
It can be assumed that the effect of using this option for machines with terabyte disks will be even more obvious.

I note that Quick Rollback can also be used when restoring VMs “in 1 click” from the Veeam Backup Enterprise Manager web console (since this is just the built-in script to completely restore the VM to its original location):

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Are there any pitfalls?


Let's talk about this. As mentioned above, Quick Rollback uses Modified Block Information (CBT). However, this information in a number of emergency situations cannot be considered 100% reliable. That is why this option is disabled by default, and users are strongly recommended to use it only in cases where the problem at the guest OS level led to the need for recovery.
If the cause was a hardware-level problem (for example, with a host or storage system) or a sudden voltage drop, then using Quick Rollback is not safe
- in such situations there is a high probability of distortion of the SVT data, and there is a risk of ruining the VM disk by starting the recovery of the wrong blocks.

Do not forget about a number of restrictions on useQuick Rollback in acceptable cases:
  1. Check that the backup copy from which you are going to restore the machine was created with the CBT tracker turned on. This can be done by clicking the Advanced button in the Storage step of the backup job wizard and going to the tab of the corresponding platform (more for VMware and for Hyper-V ).
  2. You cannot perform two incremental restorations one after another - because after the first such recovery has taken place, the CBT tracker on the source VM will be “reset” and at least one incremental backup pass will be needed so that an incremental recovery can be performed again.
  3. Incremental recovery for VMware uses only two modes of data transfer - Network or Virtual Appliance. Direct SAN Access mode cannot be enabled for this scenario.

I hope that the simple recommendations given here will allow you to successfully use Quick Rollback for efficient recovery of virtual machines.

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