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Druva Documentation

About UEFI firmware support for Failover and Failback

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Earlier, during the initial implementation of Disaster Recovery, AWS was not supporting the booting of an EC2 instance with the UEFI firmware. So, if you had configured a UEFI VM, during failover it was converted into BIOS; and during failback, it was recovered in BIOS mode only.

Now, with AWS supporting the booting of an EC2 instance with Unified Extensible Firmware Interface (UEFI) firmware, draas also extends its support to the UEFI firmware during failover and failback of VMs. If you have configured a UEFI VM, during failover, you get a copy of the source machine in AWS in the form of an EC2 instance that boot with UEFI firmware, and during failback, it is recovered in UEFI mode only.

 For UEFI to UEFI failover and failback, you must upgrade both, your VMware and DR proxy to version 6.3.1 or later. 

The following diagram depicts how failover and failback work for UEFI and BIOS firmware when you have upgraded both, the VMware and DR proxies to the latest version:


The UEFI VMs are identified by the UEFI_VM_icon.jpg icon on the VM listing page of the Management Console:


You can see the firmware of the VM selected for failover or failback on the jobs logs page:


Key considerations

  1. For UEFI to UEFI failover and failback, you must upgrade both, your VMware and DR proxy to version 6.3.1 or later. 

  2. We recommend running backup of the VM with the latest VMware proxy version.

  3. Disaster Recovery supports backward compatibility for failover or failback of VMs. See the following table for backward compatibility scenarios:



Source VM

Failover EC2 instance

Failback VM

VMware and DR proxies older than version 6.3.1







As shown in the table, if the configured VM is of UEFI firmware, but you have not upgraded the proxies to version 6.3.1 or later, during failover, it is converted to a BIOS EC2 instance, and during failback, it is recovered in the BIOS mode only.

If the configured VM is of BIOS firmware, failover and failback happens in BIOS mode only.

  1. For VMs with UEFI firmware, we recommend using the nitro instances only (c5 and m5).

  2. If your proxy is older than version 6.3.1, failover might fail if the selected VM for failover if it is of UEFI firmware, and the source VM has a boot disk that is more than 2 TB in size or has more than 4 partitions in the boot disk.

  3. During failback of UEFI VMs, the Backup proxy pool will be disabled if none of the VMware proxies in the pool is of version 6.3.1 or later.

  4. AWS supports booting of the EC2 instance in BIOS mode only for the following operating systems even if the source VM might be of UEFI firmware in the vCenter. Druva does not support the failover conversion of such VMs.

    1. RHEL 6.3 to 7.3

    2. Centos 6.3 to 7.3

    3. Oracle Linux 6.1 to 7.4

    4. Suse Linux 11 SP1 to 12 SP1

    5. Ubuntu version below 14.04 

    6. Windows version below 2008 R2

For more information, see Disaster recovery support matrix, prerequisites, and limitations.