Tired of the same old punditry and OS wars? Want to read something practical you can actually use and apply to your real job? Or perhaps you need some light reading material to help you get some sleep on the plane between consulting engagements – either way, welcome to the first in what I hope will be a series of technical HOWTO articles, entitled “Geek Sheets”.
One of my favorite Linux tools and live CD distributions is the System Rescue CD. It allows you to boot up on any x86-based, PowerPC and SPARC-based machine and perform any number of backup and recovery tasks on Linux, Mac, Solaris and Windows-based systems. The System Rescue CD can even be booted on completely diskless systems on a USB stick or PXE-booted over the network. In another publication, I went into depth on how to use some of System Rescue CD’s basic functions and how to bare-metal image a typical desktop and server Linux or Windows configuration.
However, that article was aimed at an end-user or utility computing scenario using fixed file system configurations using local storage and not on an enterprise server machine. For storage flexibility, many Linux server systems today now use LVM, or Logical Volume Manager, rather than use fixed file system partitioning that desktop distributions such as Ubuntu typically use. This adds a layer of abstraction on top of the bare metal partition layout and introduces some complexity as to how these systems can be imaged.
As a best practice, enterprises should look to do SAN-based replication and disaster recovery for a system imaging and snapshot solution. However, we all know that it isn’t always cost effective or practical to have a boot from SAN or SAN-replicated server infrastructure, and it may sometimes be desirable – such as during a data center move – to have a bare-metal “snapshot” backup of an entire system on a network file store or a portable storage device where everything can be quickly restored as it was without having to do some sort of complicated rebuild. I recently had to perform this for an engagement I was working on and it dawned on me that this procedure, while probably very useful, was not documented anywhere in one place.
The good news is that it can still all be done with standard Linux tools, System Rescue CD and without any expensive proprietary software. The bad news is that nobody has automated the process. I’m hoping that some enterprising college or high school kid looking for a summer project will take the information I am posting here and create a utility or script for inclusion in the next System Rescue CD build. Can you say “Google Summer of Code?”
I would like to give special thanks to Durham, NC-based Linux sysadmin Mike Brennan for helping me to develop this procedure.
