Chapter 17. Recovering and restoring a system To recover and restore a system using an existing backup, Red Hat Enterprise Linux provides the Relax-and-Recover (ReaR) utility. You can use the utility as a disaster recovery solution and also for system migration. The utility enables you to perform the following tasks: Produce a bootable image and restore the system from an existing backup, using the image. Replicate the original storage layout. Restore user and system files. Restore the system to a different hardware. Additionally, for disaster recovery, you can also integrate certain backup software with ReaR. 17.1. Setting up ReaR and manually creating a backup Use the following steps to install the package for using the Relax-and-Recover (ReaR) utility, create a rescue system, configure and generate a backup. Prerequisites Necessary configurations as per the backup restore plan are ready. Note that you can use the NETFS backup method, a fully-integrated and built-in method with ReaR. Procedure Install the ReaR utility: Modify the ReaR configuration file in an editor of your choice, for example: Add the backup setting details to /etc/rear/local.conf . For example, in the case of the NETFS backup method, add the following lines: Replace backup.location by the URL of your backup location. To configure ReaR to keep the backup archive when the new one is created, also add the following line to the configuration file: To make the backups incremental, meaning that only the changed files are backed up on each run, add the following line: Create a rescue system: Create a backup as per the restore plan. For example, in the case of the NETFS backup method, run the following command: Alternatively, you can create the rescue system and the backup in a single step by running the following command: This command combines the functionality of the rear mkrescue and rear mkbackuponly commands. 17.2. Scheduling ReaR The /etc/cron.d/rear crontab file in the rear package runs the rear mkrescue command automatically at 1:30 AM everyday to schedule the Relax-and-Recover (ReaR) utility for regularly creating a rescue system. The command only creates a rescue system and not the backup of the data. You still need to schedule a periodic backup of data by yourself. For example: Procedure You can add another crontab that will schedule the rear mkbackuponly command. You can also change the existing crontab to run the rear mkbackup command instead of the default /usr/sbin/rear checklayout || /usr/sbin/rear mkrescure command. You can schedule an external backup, if an external backup method is in use. The details depend on the backup method that you are using in ReaR. Note The /etc/cron.d/rear crontab file provided in the rear package is considered deprecated, see Deprecated functionality shell and command line , because it is not sufficient by default to perform a backup. 17.3. Using a ReaR rescue image on the 64-bit IBM Z architecture Basic Relax and Recover (ReaR) functionality is now available on the 64-bit IBM Z architecture and is fully supported since RHEL 8.8. You can create a ReaR rescue image on IBM Z only in the z/VM environment. Backing up and recovering logical partitions (LPARs) has not been tested. Important ReaR on the 64-bit IBM Z architecture is supported only with the rear package version 2.6-9.el8 or later. Earlier versions are available as a Technology Preview feature only. For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview . The only output method currently available is Initial Program Load (IPL). IPL produces a kernel and an initial RAM disk (initrd) that can be used with the zIPL boot loader. Prerequisites ReaR is installed. To install ReaR, run the yum install rear command Procedure Add the following variables to the /etc/rear/local.conf to configure ReaR for producing a rescue image on the 64-bit IBM Z architecture: To configure the IPL output method, add OUTPUT=IPL . To configure the backup method and destination, add BACKUP and BACKUP_URL variables. For example: Important The local backup storage is currently not supported on the 64-bit IBM Z architecture. Optional: You can also configure the OUTPUT_URL variable to save the kernel and initrd files. By default, the OUTPUT_URL is aligned with BACKUP_URL . To perform backup and rescue image creation: This creates the kernel and initrd files at the location specified by the BACKUP_URL or OUTPUT_URL (if set) variable, and a backup using the specified backup method. To recover the system, use the ReaR kernel and initrd files created in step 3, and boot from a Direct Attached Storage Device (DASD) or a Fibre Channel Protocol (FCP)-attached SCSI device prepared with the zipl boot loader, kernel, and initrd . For more information, see Using a Prepared DASD . When the rescue kernel and initrd get booted, it starts the ReaR rescue environment. Proceed with system recovery. Warning Currently, the rescue process reformats all the DASDs (Direct Attached Storage Devices) connected to the system. Do not attempt a system recovery if there is any valuable data present on the system storage devices. This also includes the device prepared with the zipl boot loader, ReaR kernel, and initrd that were used to boot into the rescue environment. Ensure to keep a copy. Additional resources Installing under z/VM Using a Prepared DASD .

Commands:
yum install rear
vi /etc/rear/local.conf
BACKUP=NETFS BACKUP_URL= backup.location
NETFS_KEEP_OLD_BACKUP_COPY=y
BACKUP_TYPE=incremental
rear mkrescue
rear mkbackuponly
rear mkbackup
BACKUP=NETFS BACKUP_URL=nfs:// <nfsserver name> / <share path>
rear mkbackup