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1.9. Performing System Rescue and Creating System Backup with ReaR

When a software or hardware failure breaks the operating system, you need a mechanism to rescue the system. It is also useful to have the system backup saved. Red Hat recommends using the Relax-and-Recover (ReaR) tool to fulfil both these needs.

1.9.1. What is ReaR and Which Tasks it Can Be Used for

ReaR is a disaster recovery and system migration utility which enables you to create the complete rescue system. By default, this rescue system restores only the storage layout and the boot loader, but not the actual user and system files.
Additionally, certain backup software enables you to integrate ReaR for disaster recovery.
ReaR enables to perform the following tasks:
  • Booting a rescue system on the new hardware
  • Replicating the original storage layout
  • Restoring user and system files

1.9.2. Quickstart to Installation and Configuration of ReaR

To install ReaR, enter as the root user:
~]# yum install rear genisoimage syslinux
Use the settings in the /etc/rear/local.conf file to configure ReaR.
For further information see, Section 26.1, “Basic ReaR Usage”.

1.9.3. Quickstart to Creation of the Rescue System with ReaR

To create the rescue system, perform the following command as the root user::
~]# rear mkrescue
For further information on creating the rescue system with ReaR, see Section 26.1.3, “Creating a Rescue System”.

1.9.4. Quickstart to Configuration of ReaR with the Backup Software

ReaR contains a fully-integrated built-in, or internal, backup method called NETFS.
To make ReaR use its internal backup method, add these lines to the /etc/rear/local.conf file:
BACKUP=NETFS
BACKUP_URL=backup location
You can also configure ReaR to keep the previous backup archives when the new ones are created by adding the following line to /etc/rear/local.conf:
NETFS_KEEP_OLD_BACKUP_COPY=y
To make the backups incremental, meaning that only the changed files are backed up on each run, add this line to /etc/rear/local.conf:
BACKUP_TYPE=incremental
For detailed information about using the ReaR NETFS internal backup method, see Section 26.2.1, “The Built-in Backup Method”.
For information on supported external backup methods and unsupported backup methods, see Section 26.2.2, “Supported Backup Methods” and Section 26.2.3, “Unsupported Backup Methods”.