Linux is a really stable and powerful operating system, just like its Unix cousins. It is also very secure if set up properly and maintained well. However, despite all this, accidents do happen, whether you accidentally type "rm -R /" or someone breaks into your machine from the internet. That's why you need a good backup plan. If you have a cd burner and some blank discs, then this tutorial is just for you. Do note however that a full backup may not work well after being restored to a machine with different hardware. If your hardware is damaged for some reason and you are forced to buy different hardware, your system may not run as well as it should after restoration. Chances are that you will encounter no problems though and it can't really hurt anything to try, so don't be afraid to try a complete restoration even if you do have new hardware.

The frequency at which you need to backup depends on how quickly the data on your hard drive changes and how important the data is. Obviously if you keep important documents on your hard drive that are worth a lot to you or your company, then you should probably keep several sets of discs and rotate through them backing up every day. That way if your computer had been compromised a few days ago but you just found out, you'll have a set of discs with an uncompromised backup to restore. It may be a lot of work but what's it worth to you? In my case, I have data on my computer that I don't want to lose but it's collected over a long period of time and doesn't change at a fast pace. Also I don't mind if I have to redo a few things to get my computer back to where it was. Therefore I only backup every few weeks. The choice is up to you.

Now there are two mediums that you can use to make backups. The first is called cd-r. These discs can only be written to once. They're cheap but for backup purposes, will leave you paying more in the long run. The second medium is called cd-rw. These discs are considerably more expensive than cd-r discs, perhaps even twice as much. However the extra cost is well worth it. These discs can be recorded on thousands of times. You're more likely to lose or break the discs than have them wear out from too much recording. They usually record a little slower too, but most people would prefer the extra time over extra money. I went out and bought a 25 pack of cd-rw discs and now I don't have to worry about buying anymore until I have more data than will fit on 25 discs.

First of all, what we want to do is put all of the information on your hard drive into a tarbell. This is a file that contains many other files which have been compressed. For Windows users, it's similar to a .zip file. To do this, it helps to be in single user mode. This way we don't have a lot of temporary files opened that don't need to be backed up. To do this, you simply log in as root at a terminal (type "su -" if you're already logged in as your normal user) and type "shutdown now". It will look like it's rebooting but will never actually reset. Next it will ask you for your root password. Go ahead and type it in. It should then bring you to a command prompt. At that point, you issue this command:

tar -cvzf /backup.tar.gz /

This will backup everything on your system into one tarbell file. This will take a while and isn't very interesting so go find something to eat or get some fresh air. When it finished, you can switch back to multiuser mode. Just type "telinit 2" replacing 2 with your default runlevel. If you don't know what it is, just do "shutdown -r now".

You should eventually get back to the login screen. Log back in as root. Now this file is probably far too large to fit on a single cd. Obviously you're going to have to break it up into several pieces. That's what the split command is for. You may think 650 megs is 650 million bytes, but this is not exactly true. It's actually a little over 681 million bytes. This is because there are 1024 bytes in a kilobyte, and 1024 kilobytes in a megabyte. But I recommend going a bit under the actual size of the cd because it has to make a table of contents and all that jazz. I think 675 million bytes is a good size for each of the split files. If you have 700 meg cd's, I'd go with 725 million bytes per split.

Well first, you have to be at the root directory where the backup is. Simply type "cd /". Now we'll use the split command. At the command line, type this:

split -b 675000000 backup.tar.gz

This will split our huge files into cd-sized fragments. It will leave a series of files called xaa, xab, xac, etc depending on how large your original file was. Run "ls" to see all the files.

Now that we have our fragmented files, it's safe to delete the monolithic file. This can be accomplished with "rm backup.tar.gz". It may take a few seconds since it's a big file. Next we want to make iso images of all of the fragmented files. Iso images are files that are an exact copy of what have been or should be on a cd. All burning software makes iso images before it starts burning, even if it isn't obvious. For this, Linux has a mkisofs command. There's not really much to the command. I'm going to give you a compound command that can take care of all the files in one command.

for i in `ls xa*`; do echo -e "$i"; mkisofs -o $i.iso $i; done

The echo part of the command will help you keep up with the progress. This could also take a while. When it's finally finished, you can finally burn the images to cd's. Make sure you label the discs. Your backup will be worthless if you don't remember which order they go in. There are several burning programs available for Linux like X-cd-roast. If you want to use one of these, that's fine, but they're beyond the scope of this document. I am sticking to the command line. Now to record cd's, you'll need to know where your burner is on the SCSI device(s). If you don't already know, you can execute "cdrecord -scanbus" to find out. It will display an array of numbers. On one of these lines, it should display the manufacturer and model of your burner. You'll need the preceding three numbers for using cdrecord. If your burner doesn't show up, then you probably have an IDE burner. You'll need to set up SCSI emulation into the kernel, but that also is beyond the scope of this tutorial. Now you hopefully know where your burner is on the SCSI chain. From xaa.iso to the final iso, run this command:

cdrecord -v blank=fast speed=2 dev=0,0,0 xaa.iso

Make sure you have a blank cd in the drive before each time you run this command. Each time you run it, change xaa.iso to the next file in line. I need to explain some of the options in this command. First of all, the "dev=0,0,0" specifies the logical location of your burner. Replace this with the number you got from earlier. The "speed=2" option specifies how fast your burner can burn cd's. As you can tell, I have an old slow burner. Do realize that most burners burn at a different speed for cd-r discs and cd-rw discs. Consult the manual or the box it came in for the speed of it. Last of all, the "blank=fast" option is used to erase a cd-rw disc if there is data on it. Even if the disc is new and hasn't yet been written to, it's safe to use this option. If you use cd-r discs, you can omit this option.

Congratulations! You should now have a cd backup of your system. If you would like to combine all of that into a script file, it's quite simple. I won't go into how to make a script file since it involves many steps, but I will give you the contents of my script file. The first step of creating the tarbell needs to be done in single-user mode, so I have left that part out of the script.

cd /
echo -e "splitting tar"
split -b 675000000 backup.tar.gz
echo -e "removing original tar"
rm backup.tar.gz
echo -e "making iso images"
for i in `ls xa*`
do echo -e "$i"
mkisofs -o $i.iso $i
done
echo -e "removing broken tars"
rm xa[a-z]
echo -e "start recording to cd"
for i in `ls xa[a-z].iso`
do echo -e "insert blank disc and press ctrl+d"
cat >> /dev/null
cdrecord -v blank=fast speed=2 dev=0,0 $i
done
echo -e "removing iso images"
rm xa[a-z].iso

Now that you have backups, you need to know how to restore them. Well luckily it's a bit less complicated than backing them up. However, you will need a partly functioning Linux system in order to restore. As long as you can get to the command line as root, you're probably good to go. Otherwise you may have to reinstall Linux before you can proceed with restoration. I'll assume you have Linux working already and proceed with the tutorial.
First of all, you have to get those split files off of the cd's and put them onto your hard drive. You can either copy them all from your cd's and then join them together, or you can join them as you copy them. The latter choice requires less free hard drive space so I'll explain that method.

First, you must mount your cd-rom. For me, it is done like this:

mount /cdrom

On many Linux distros, you would replace /cdrom with /mnt/cdrom. If neither of these will mount, then your cd-rom is probably not set up and you'll need to take care of that. But again, that's not directly related to this tutorial so I won't go into that.

Next, you need to copy the files one by one into a massive zip file on your hard drive. We named the file backup.tar.gz before it was split, so why not name it the same thing again? It really doesn't matter what you name it though as long as it ends with .tar.gz. Moving right along, to copy the first fragment to the file, type this:

cp /cdrom/xaa /backup.tar.gz

Again, depending on your distro, you may need to change /cdrom to whereever your cd-rom gets mounted to. It could take a few minutes because this file is huge. This is where it's nice to have something else to do (like watch television) while the file is copying, especially if you have a lot of cd's to go through.

After the first file is finished, you will need to unmount your cd-rom drive. You cannot remove the cd until you unmount it. Simply use the umount command like so:

umount /cdrom

Note that umount does not have an 'n' in it. Don't ask me why. I can only guess that some programmer wasn't all that great at spelling. If your backup is on only one cd, you can skip the next few steps and continue to extracting the file.

Otherwise, next you'll need to put the second cd in and mount it just like before. What is different though is that you won't be copying the file to the hard drive, you'll be appending it to the one that's already there. You go about that like this:

cat /cdrom/xab >> backup.tar.gz

Just like before, this can take a few minutes. Continue swapping cd's and concatenating (joining) the files until you've ran out of cd's. Now you have your original zip file.

To extract that baby, type:

tar -xvpzf backup.tar.gz

This will extract the monolithic zip file to your hard drive, returning your system to roughly the way it was before the backup. This also could take a little while, but not as long as all the cd's did. Note that if there's currently a file on your hard drive that wasn't in the backup, that file will continue to remain like it is. However, if there's a file both on the hard drive and the backup, it will be overwritten. If you do not want this, you can add the k flag somewhere among those crazy letters after the hyphen. I do not recommend it when doing a full restoration though because if there are corrupt files on the disk, they will remain corrupt and if you've reinstalled, it may add programs and files without notifying other programs of their existance. (For instance, in Debian, it could install a program but since it doesn't overwrite dpkg's database file, dpkg wouldn't know it was installed and that could have serious consequences.) So unless you're just restoring /home or something that won't affect how the system works, or you really know what you're doing, don't use the k option.

Also, if you've reinstalled Linux since the backup or you've compiled another kernel, you'll need to run lilo to avoid crashes during reboot. Even if you haven't done either of these, it still wouldn't be a bad idea. Simply type "/sbin/lilo" at the command line as root and hopefully all will go well. I can't think of any reason it wouldn't unless the configuration was misconfigured before backup.

That's it! If you follow this tutorial, you should be safe should disaster hit. If you want more information on specific commands, type "man" followed by a space and the command name. If you have questions or problems that the man pages couldn't help, contact me at snailboy1@yahoo.com. I usually respond within a day. Enjoy the power and versatility of Linux.