Dell NetWorker 19.9 Administration Guide

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Overview of Windows Bare Metal Recovery (BMR)

Bare Metal Recovery (BMR) is data recovery and restoration where the backed up data is available in a form that allows you to restore a system from bare metal, that is, without any requirements as to previously installed software or operating system. Typically, the backed up data includes the necessary operating system, applications, and data components to rebuild or restore the backed up system to an entirely separate piece of hardware. The hardware receiving the restore should have a similar configuration as that of the hardware that was the source of the backup. The basic BMR is the process of bringing up a server after a disaster and ensuring that the system recovers with the operating system, the applications, and the data as they were at the time of the failure.

NetWorker Windows BMR is an automated recovery solution that uses the Windows ASR writer and other Microsoft VSS writers to identify critical volumes and perform a full recovery on a target host.

NetWorker Windows BMR supports file system backup and recovery of critical volumes. NetWorker Module for Microsoft (NMM) supports application data backup and recovery. Additional backup and recovery procedures are required to backup and restore application data. The NMM documentation provides specific instructions on how to backup and recover applications.

You can use Windows BMR to recover a backup from a physical host. You can also use Windows BMR to recover a VMware virtual machine or VMware CD to a physical host, VMware virtual machine, or a VMware CD.

NetWorker uses a special save set called DISASTER_RECOVERY:\, a subset of the ALL save set, to backup all the data that is required to perform a Windows BMR. NetWorker performs the BMR backup while the Windows operating system is active. You can recover an offline BMR backup without first reinstalling the Windows operating system. This action prevents problems that can occur when you restore operating system files to a running version of Windows.

To support a NetWorker Windows BMR recovery, download the Windows BMR image from Online Support website. This image enables you to create a bootable Windows BMR ISO that contains NetWorker binaries and a wizard, which controls the recovery process.

NOTE:The NetWorker E-LAB Navigator provides more information about operating systems support for Windows BMR.

Components of the DISASTER_RECOVERY:\ save set

The DISASTER_RECOVERY:\ save set contains a group of component save sets that are required to perform a Windows BMR recovery. A full backup of the DISASTER_RECOVERY:\ save set contains the following components:

All critical volumes.
WINDOWS ROLES AND FEATURES:\ (a subset of the DISASTER RECOVERY:\ and ALL save sets).
System Reserved partition.
UEFI partition (if available).

NetWorker supports full and incremental backup levels of the DISASTER_RECOVERY:\ save set. Also, when the Windows BMR recovery operation recovers data from an incremental backup, the recovery operation recovers all incremental backups.

The first time NetWorker performs a backup of the DISASTER_RECOVERY:\ save set, NetWorker performs a level Full backup, regardless of the level that is defined for the backup.

When you configure a level Incremental backup of the DISASTER_RECOVERY:\ save set, NetWorker backs up some components of the save set at a level Full, and other components at an Incremental level.

The following table summarizes the backup level of each save set component of the DISASTER_RECOVERY:\ save set, when you perform an incremental backup:

Table 1. DISASTER_RECOVERY:\ components in an incremental backup
Save set	Backup level
Critical volumes	Incremental
WINDOWS ROLES AND FEATURES:\	Incremental
UEFI partitions	Full
System reserved partition	Full

During an incremental backup, the backup operation checks both the modification time and the archive bit to determine if a file must be backed up. The backup operation ignores the archive bit when you assign the nsr_avoid_archive variable a value of Yes on the client host. As a result, NetWorker only uses the modification time to determine which files to back up.

Use the environment variable nsr_avoid_archive with caution. If you use the environment variable nsr_avoid_archive, test the BMR backup image to ensure that you can recover the Windows system state correctly. Performing a BMR recovery to a physical computer provides more information on validating the BMR backup image.

A Windows BMR recovery requires a successful backup of each component save set in the DISASTER_RECOVERY:\ save set. If one component of the save set fails, then the backup operation fails. For a scheduled backup, NetWorker retries the DISASTER_RECOVERY:\ backup. The number of retries that NetWorker performs is based on the value that is defined in the client retries attribute of the protection group that the Client resource is assigned to.

NOTE:In NMC Administration GUI, the Log tab of the Monitoring window, or the Save Set tab of the Media window displays each component save set of a DISASTER_RECOVERY:\ backup.