Using external HB for backup & OS testing

I am thinking of buying an external hard drive with the intent to use it for the purposes of backup of my data. As there will be sufficient spare space available I was considering using it to trial other OS.

My reason for using the external drive is that in the past I had to do a complete reinstall of Ubuntu as removing a beta that I was looking at from the system by deleting the partition that it was on rendered my system useless. I now have a laptop on which I dual boot windows 7 and Ubuntu 10.04 and is this is my only system I do not wish to corrupt it by my experimenting with other OS.

On perusing the forum I noted a post “External Hard Drive in October 2010” in which Mark Greaves suggested that the hard drive should be removed to ensure that Grub properly located on the external drive. This scares the life out of me as my technical level of competence is nil.

So far anything that I have seen on various forums and Ubuntu documentation is dated or confuses me. Can anyone please advise if there is an up to date set of instructions of on how I can load other OS on to an external hard drive suitable for a dummy?

Recently I attempted to try a new OS from a live DVD only to find that it would not effect a wireless connection. The magazine that issued the disk was singing the praises of KDE and I was interested to see what it looked like. As my previous efforts in removing an OS from the system caused so many problems there was no way that I was putting it near my HD.

Your kind assistance will be appreciated.

Have a look at this thread.
It might be just what you need.

Here is the problem you had… GRUB, (the main Linux bootloader) gets installed in 2 places…

  1. The MBR (Master boot record) of a drive… at the time you had a single drive, so GRUB stage 1 got installed to its MBR, overwriting the Windows bootloader… this was all well and good, and deleting any partitions would not affect the MBR.

  2. The ‘rest’ of GRUB (stage 2), including its configuration files were stored on your Linux partition… these configuration files contained the information GRUB needed to boot Windows as well as Linux.

There is not enough space available in the MBR for a full modern bootloader that is capable of booting multiple OS’s, as it requires helper applications such as os-prober, and the configuration files which tell it where the OS’s are located.

OK, with 2 hard drives, you have 2 options…

  1. Have GRUB stage 1 on the MBR of the primary hard drive (the one that’s set to boot first in the BIOS) and the rest of grub on any partition on either drive… second drive has nothing in its MBR

  2. Have a GRUB stage 1 in the MBR of both drives… making both hard drives FULLY bootable without the need for each other.

Think about this… you attach your new external drive, and run a default install of say Linux Mint installing it to your external drive… by default, GRUB stage 1 on your internal drive will be overwritten by another GRUB stage 1, the rest of GRUB will be installed to the EXTERNAL drive and the new GRUB stage 1 will point to it, so if you ever format that drive, or even just unplug it… NEITHER drive will be bootable.

Remember I did say a “DEFAULT” install… there are ways round this, but things start to become more complex…

  1. When installing the new OS to the external drive, make sure GRUB stage 1 on the internal drive doesn’t get overwritten… ie. tell the installer not to install GRUB, then get the existing GRUB to probe for the new OS. (external drive’s OS will ONLY be bootable when it is attached to this system)… but you will still not be able to delete the Linux installation on the internal drive as it contains GRUB stage 2

  2. Have a GRUB satge 1 and stage 2 on BOTH drives… easiest and safest way to achieve this, remove the internal drive whilst installing to the external drive, then just do a default install… this can be achieved without disconnecting the drive, but if you get it wrong… (in this configuration BOTH drives/OS’s are FULLY bootable, you just select the drive you want to boot from as the first boot device in the BIOS, and removing the external drive will not stop you booting from the internal drive… you will also be able to boot the external drives OS on any PC you attach the drive to)

  3. Create a separate /boot partition on the internal drive for GRUB stage 2… so you have GRUB stage 1 on the internal drives MBR, and GRUB stage 2 on its own partition… as long as you don’t delete THIS partition, removing other partitions and OS’s will NOT affect booting… you will also be able to remove the external drive and replug it without issues, but it will not be bootable on another PC.

So really I was just giving the safest and most flexible way when I said to remove the internal drive during installation to the external drive :wink:

And you had not lost Windows when you deleted the Linux partition(s)… it was still there just not bootable… reinstalling GRUB or the Windows bootloader would have fixed it.

There’s no way round the fact that if you want to install multiple OS’s for experimentation, you are going to have to…

  1. Get up to speed on how bootloaders work, and where they store their files… GRUB in particular.

  2. Learn how to reinstall GRUB and the Windows bootloaders, for if/when things go wrong.

My thanks to you both for your replies.

galaxytdm

Your link looks good except Google does not give any help on where I can buy it. Posted on link and hope that the info can be provided.

Mark

What I an looking for is to keep anything that may cause problems with my working system totally away. Buying an external HD looked the best option both for the lack of space taken up and cost against purchasing a new system. I had hoped that by doing this I could safely test / experiment with other OS and software.

If I get lucky with finding the source of the preloaded drive then I shall go down that road. Failing that from what you say I will have a lot to study before I get much older.

Wish me luck

Again my thanks to you both