About instant recovery of a Hyper-V virtual machine

Last published : Apr 02, 2026
Backup Exec lets you recover a virtual machine instantly from a backup set without waiting to transfer the virtual machine's data. Backup Exec starts the instantly recovered virtual machine directly from the backup set and users can access it on the Hyper-V host immediately. The startup time depends on the network speed and storage speed and not on the size of the virtual machine. You can use an instantly recovered virtual machine to perform the same operations as a virtual machine.
An instantly recovered virtual machine can be used to do the following:
  • Access and restore individual files and folders from a virtual machine.
  • Test a patch on an instantly recovered virtual machine before you apply the patch to production systems.
  • Verify the backup image of the virtual machine and the applications.
  • Verify an application within the instantly recovered virtual machine.
  • Recover the instantly recovered virtual machine permanently by using Hyper-V Live migration or Storage migration. In a disaster recovery scenario, you can instantly recover a virtual machine in minutes and then schedule a migration to move it to a permanent storage on a Hyper-V host. The instantly recovered virtual machine remains available even during the migration process, which decreases the amount of downtime.
    Note: You cannot back up instantly recovered virtual machines with the Agent for Hyper-V until you migrate the virtual machine from Backup Exec server storage and also remove from the virtual machine from Backup Exec server storage.
If you remove an instantly recovered virtual machine, any changes that you made are lost. Migrate the virtual machine from the Backup Exec server storage and remove it from Backup Exec to retain the changes or back up the instantly recovered virtual machine with the Agent for Hyper-V.
When you run an instant recovery job, the selected backup set is exposed to the Hyper-V host through an SMB share that is created on the Backup Exec server. The instantly recovered virtual machine disks are on the Backup Exec storage but they use the CPU of the Hyper-V host for their functions. All read operations are redirected to the Backup Exec server and the write operations are saved in a differencing disk at the location that is mentioned in the Destination for VM registration and checkpoint field when you create an instant recovery job. This path is on the Hyper-V host on which you want to recover the virtual machine.
Note: Backup Exec alerts you every week about the number of instantly recovered virtual machines running on the server. By default, the alert is triggered every Friday at 2.00 PM.
The following table describes the instant recovery process for a virtual machine.

Table: Instant recovery process for a Hyper-V virtual machine

Step Description
Step 1 You run an instant recovery job from a backup of a Hyper-V virtual machine.
Step 2 The Backup Exec server virtualizes the backup set.
Step 3 Backup Exec creates an SMB share.
Step 4 Backup Exec creates a virtual machine on the Hyper-V host.
Step 5 Backup Exec creates a snapshot of the virtual machine so that the writes can be made to the local disk.
Step 6 Backup Exec starts up the virtual machine automatically if you select the option to power on the virtual machine after it is recovered.
Step 7 (optional) You use Live Migration or Storage Migration to migrate the virtual machine from Backup Exec server storage if you want to save any changes that
were made to the virtual machine.
Step 8 You run a job to do one of the following\:
- Remove an instantly recovered virtual machine that you no longer need to use.
- Remove the instantly recovered virtual machine from Backup Exec server storage after you migrate the virtual machine.
Warning: You cannot upgrade Backup Exec until you remove all of the instantly recovered virtual machines.
Instant Recovery Resiliency
As Backup Exec has enhanced the resiliency for instantly recovered virtual machines, if you restart the Backup Exec server, restart the Hyper-V server, or if there is a network connectivity issue, any changes that you made to the virtual machine are no longer lost. After either of these servers restart, the Backup Exec services start up and the virtualization process continues.
There are four scenarios for resiliency when the instantly recovered virtual machine is running on the Hyper-V host:
  • Backup Exec server restarts and the Hyper-V server is running.
  • Hyper-V server restarts and the Backup Exec server is running.
  • Backup Exec and the Hyper-V servers restart.
  • Network connectivity issues result in connection loss between the Backup Exec server and Hyper-V host.
In all these scenarios, the virtual machine starts automatically when the server restart is complete or network connectivity is restored. If the virtual machine does not start, you may require to restart it on the Hyper-V host.
Note: The virtual machine cannot be used until the server restart is complete or network connectivity is restored.
Instant Recovery Resiliency for Hyper-V uses the CORBA communication method. A configuration change may be required if you require to change the CORBA communication port on the Backup Exec server. The Backup Exec server and the Hyper-V server hosting the instantly recovered virtual machine must have the same CORBA port setting.
To change the CORBA port setting on the Backup Exec server
  1. Click the Backup Exec button, select Configuration and Settings, and then selectBackup Exec Settings.
  2. In the left pane, select Network and Security.
  3. Under Custom port Number (Oracle only), select theUse a custom port to receive operation requests from the Oracle server check box and enter the same port number as entered on the Hyper-V server.
  4. Stop and restart all Backup Exec services and rerun the backup.
To change the CORBA port setting on the Hyper-V host
  1. On the computer on which the Agent for Windows is installed, on the taskbar, click Start > All Programs > Veritas Backup Exec > Backup Exec Agent Utility.
  2. Click the Database Access tab.
  3. Select the Use a custom port to connect to the Backup Exec server during Oracle operations check box.
  4. Enter a port number that is not in use and can be used by Backup Exec and then click OK.
    Note: This port number must match with what is configured on the Backup Exec server.
  5. Restart the Backup Exec Remote Agent Service on the Hyper-V server.
Difference between an instantly recovered virtual machine and a restored virtual machine
Instant recovery of a virtual machine is different from a virtual machine restore in some aspects.

Table: Differences between an instantly recovered virtual machine and a restored virtual machine

Item Instant recovery of a virtual machine Restore of a virtual machine
Data transfer Does not transfer the virtual machine data to the instantly recovered virtual machine. Transfers all data from the backup set to the restored virtual machine.
Job time Instant recovery job runs instantly and no backup data is transferred. Therefore, the job time depends on the time taken to share the backup set and register the virtual machine. Restore time depends on the size of the virtual machine and the network speed and storage speed.
Read/write operations Uses the backup set image for all read operations. It uses a snapshot on the Hyper-V server for all write operations. All data is already moved to the Hyper-V server. Therefore, there is no dependency on the Backup Exec server.
Data storage Uses the Backup Exec server storage until you migrate the instantly recovered virtual machine. Already uses the Hyper-V server storage.
Server restart As the Instant Recovery resiliency is enhanced, if the Backup Exec server or the Hyper-V server restarts, the instantly recovered virtual machines remains accessible. Restarting the Backup Exec server or the Hyper-V server has no effect on the restored virtual machine.
In case of network connectivity issues the instantly recovered virtual machines are accessible after the connectivity is restored.
If the virtual machine does not start, you may require to restart it on the Hyper-V host.
See Requirements for instant recovery of a Hyper-V virtual machine.
See Creating an instant recovery job for a Hyper-V virtual machine.
See About removing an instantly recovered Hyper-V virtual machine.
See Notes about instant recovery of a Hyper-V virtual machine.