Boot CD must be created to restore the backup for doing bare metal restore, boot CD helps to restore the backup without having the operating system or software installed on the target machine. It also provides automatic recovery of data without user intervention. Automatic restoration can be done by creating the CD after executing the prepare to restore, otherwise you can do normal restore ( You need to select the configuration that you want to restore). Here i will be doing automatic restoration of machine, so prepare your machine for similar or dis-similar restore.
In any bare metal recovery utilities the devil is in details and relax-and-restore managed to account for most important details right. That's why despite it fragility it is a valuable backup solution:
Still despite all those warts ReaR can be used, as default configuration that create the rescue disk alone is worth some studing of this software. Moreover more complex configuration can be debugged using try and error process. As linux does not have any built-in bare metal recovery utility other then DD (but with it you face problemwriting zeros on unused parts of filesystem before making backup with it in order to save space) you actually do not have too many alternatives ;-).
While "added complexity" often kills such packages, the issues in bare metal recovery are complex and at least as a "poor man" bare metal backup this package is a good candidate. It allows you to understand what is involved and how to solve certain problems inherent in bare metal backup. And what is important is that in simple cases it works as expected. So if you do not need to deviate from typical operations too much, for example, just adding the exclusion of some filesystems from the backup, you are OK. But you need to test whether it is able to restore the system (which, of course, also is not given). but if you tarball is right, you can always restore it without rear scripts. That's huge advantage as stakes in such cases are very high.
When it works you have a bare metal recovery solution created using basic Linux components. Of course you can always install minimal OS on the USB drive and create tar manually. On systems where relax and recover blue screen on recovery this in the next option to try. But it requires shutting the server down and rebooting it from installation DVD or remotely mounted ISO to create the image. You can also do it on the fly by copying the OS manually and then installing grub and modifying grub menu to appropriate harddrive. But this requires some knowledge of grub.
Relax-and-Recover uses tar with the set of tar options and exclude files to created the tarball which later would be used to restore the system. If backup is not too large it can be put on permanently inserted FIT form factor USB drive. The current upper size for this low profile form factor is 256 GB (SanDisk 256GB Ultra Fit USB 3.1 ). The same upper limit has metal bar form factor (SanDisk Ultra Flair). Larger size "bar" form factor likePNY Pro Elite 512GB scale to 512GB, but that does not make much sense as the SSD drive of the same capacity costs less. That means that you can backup on 256GB flash drive filesystem with approximately 512GB of used space (assuming 50% compression). After that it is better to use USB 3.0 External hard drives such as Samsung T1 orSamsung T3, which are almost twice cheaper.
Relax-and-Recover (Rear) is a bare metal disaster recovery and system migration solution, similar to AIX mksysb or HP-UX ignite. It is composed of a modular framework and ready-to-go workflows for many common situations to produce a bootable image and restore from backup using this image. It can restore to different hardware, and can therefore be used as a migration tool as well. It supports various boot media (including tape, USB, or eSATA storage, ISO, PXE, etc.), a variety of network protocols (including SFTP, FTP, HTTP, NFS, and CIFS), as well as a multitude of backup strategies (including IBM TSM, HP DataProtector, Symantec NetBackup, Bacula, and rsync). It was designed to be easy to set up, requires no maintenance, and is there to assist when disaster strikes. Recovering from disaster is made very straight-forward by a 2-step recovery process so that it can be executed by operational teams when required. When used interactively (e.g. when used for migrating systems), menus help make decisions to restore to a new (hardware) environment. 2b1af7f3a8