Relax-and-Recover use cases

This chapter will describe some use cases in more detail.

Internal backup method using rsync and USB device

Suppose you want to use an USB device to store and boot the rescue image from. The very first time you want to use the USB device you need to format it (only required once of course). Therefore, connect the USB device and verify which block device name, e.g. /dev/sdb. To actual format the USB device type:

# rear -v format /dev/sdb
Relax-and-Recover 1.17.1 / Git
Using log file: /var/log/rear/rear-ubuntu-15-04.log
USB device /dev/sdb must be formatted with ext2/3/4 or btrfs file system
Please type Yes to format /dev/sdb in ext3 format: Yes
Repartition /dev/sdb
Creating new ext3 filesystem on /dev/sdb1

Now, you need to edit the /etc/rear/site.conf configuration file (be aware, treat the configuration file as a bash script file) and add the following lines:


The last line (BACKUP_URL=usb:///dev/disk/by-label/REAR-000) references the USB device with its label (created by the format command). You could also use BACKUP_URL=usb:///dev/sdb1 in our case, but a label makes it much clearer what the purpose is of the USB device, no?

To create a full backup of this system just type:

# rear -v mkbackup
Relax-and-Recover 1.17.1 / Git
Using log file: /var/log/rear/rear-ubuntu-15-04.log
Creating disk layout
Creating root filesystem layout
TIP: To login as root via ssh you need to set up /root/.ssh/authorized_keys or SSH_ROOT_PASSWORD in your configuration file
Copying files and directories
Copying binaries and libraries
Copying kernel modules
Creating initramfs
Writing MBR to /dev/sdb
Copying resulting files to usb location
Encrypting disabled
Creating rsync archive '/tmp/rear.ByJY9oowW7EG2wQ/outputfs/rear/ubuntu-15-04/20150825.0930/backup'
Archived 1829 MiB [avg 3081 KiB/sec]OK
Archived 1829 MiB in 609 seconds [avg 3075 KiB/sec]

When you do not specify a specific OUTPUT_URL definition then OUTPUT_URL=BACKUP_URL

The backup can be found on the USB device under /<usb-mountpoint>/rear/$(hostname)/YYYYMMDD.HHMM/backup directory. Be aware, these files are not encrypted so keep the USB devices in a fault to safe guard it from unauthorized people.

Integration of EMC NetWorker with Relax-and-Recover

The EMC NetWorker (or also known as Legato) versions tested with Rear were v8.0.0.1 (and higher?) For brief sake from now on we will use the abbreviation NSR for EMC NetWorker. Rear can work with NSR since rear-1.15 and higher. We assuming the Linux system is a NSR client that is capable of making a full backup towards the NSR server. Be aware, if you rely on an external backup solution to make full backups of your system make sure you have a full backup before trying out a recover via rear. That said, when using an external backup solution as NSR rear will not make any backup of the internal disks!

To use NSR as backup solution with rear just add the following in the /etc/rear/site.conf or /etc/rear/local.conf file:


To verify that the basic requirements are met just run now:

rear mkrescue

If rear is able to communicate with the NSR server it will create an ISO image named /var/lib/rear/output/rear-$(hostname).iso and you are done from the rear side. The ISO image will automatically being backed up to the NSR server by rear, so, in case of emergency you can always restore the ISO image to another computer to use it to recover this Linux system.

Just in case you are curious, you could have a look in the /var/lib/rear/recovery/ directory. You will find there two files starting with nsr_

nsr_server (contains the NSR server hostname)
nsr_paths  (lists the mount points of file systems to restore via NSR)

To recover via NSR, then first of all boot from the ISO file created during the mkrescue phase and at the root prompt just type

rear -v recover

That should be it, after a full restoration via NSR of all internal file systems, rear will make the disk bootable and keeps everything mount under /mnt/local for further inspection before rebooting.

Integration of FDR/Upstream with Relax-and-Recover

Beginning with version 1.18, ReaR has support for FDR/Upstream. To enable this support, add the following line to either /etc/rear/local.conf or /etc/rear/site.conf


If your FDR/Upstream software is installed somewhere other than the default location of /opt/fdrupstream, that should be specified as well:


ReaR does not perform FDR/Upstream backups. ReaR is used to provide a working system to which an FDR/Upstream restore can be performed. A sample workflow follows.


On the target system (the system being backed up), edit /etc/rear/local.conf or /etc/rear/site.conf to include:


On the target system, create a bootable ISO image with this command:

/usr/sbin/rear -v mkrescue

Find the ISO image in /var/lib/rear/output/ and put it someplace safe! Store it offsite, or include it in your regular FDR/Upstream backups.

Disaster Recovery Time

On your disaster recovery hardware, boot the ISO image and follow the on-screen instructions.

The disaster recovery hardware will start FDR/Upstream and register to your storage server with the same name as the original target system.

When prompted, use FDR/Upstream Director to initiate a restore of the entire / filesystem to the /mnt/local/ directory on the target system.

When the restore is complete, return to your disaster recovery hardware and hit Enter.

Wait for ReaR to complete, and then reboot into your restored system.