Why you should install Ubuntu 8.04 (Hardy Heron) Persistent on a USB stick

There are several reasons you should install Ubuntu on a USB flash drive. First of all, a USB memory stick is easier to bring around than a Live CD if you need to install Ubuntu on a computer. But more importantly, by installing the persistent version, not only can you use your USB as a Live CD, but in addition, you can save any changes to the system to disk! In effect, this means that you have your own portable system that you can bring anywhere. Forget the worry of bringing your valuable laptop on vacation. Instead, once you have booted your system onto somebody else's computer, you can install software, perform system upgrades, and do your work on your own customized system with your own software installed. Everything you do is saved onto your USB stick. And if you do need to access or save something on the underlying system, the computer hard drives will be automounted at startup.

Naturally, your system will be limited by the disk size of your USB. Most installations use about 700 MB (the size of a Live CD) for the Live portion of the system, leaving the rest of the disk as free space. With a dirt-cheap 4 or 8 GB USB stick, you have plenty of space to install software and files.

Running a system from a USB can also be convenient if you need dedicated servers to perform exactly what you want. Rather than going through a procedure of installing necessary software and making sure that everything works on the existing system, which likely is a Windows computer loaded with crap, you simply plug in your pre-prepared USB stick and boot from it. It is cheap and quick to buy 10 USB sticks, prepare the system and software on one of them, and then replicate the entire system onto the 9 others.

Another great usage is for removal of viruses on a Windows system. Viruses are often hard to get rid of, as they might get loaded during boot-up and refuse to be deleted by the Windows antivirus application. Booting Ubuntu from the USB and running a virus scanner such as Avast or Clam (Clam is also available from repositories) should enable you to remove the viruses. See my guide for further instructions.

So how do you make such a USB stick? I just followed this guide, which was a piece of cake. If you want the USB stick to also work as a normal flash drive when connected to a computer, you might want to add a third partition in addition to the two needed for the Ubuntu Persistent system. Format it as NTFS so it is readable on both Windows and Linux systems. You might need to have this partition as the first partition for Windows to discover it. I have not tried this myself, but believe it should work.

How to compact a VirtualBox virtual disk image (VDI)

After having used VirtualBox for a while, the actual size of your virtual disk image (VDI) may have grown to become very close to the virtual size. That is, even if your guest machine system reports that it only uses a small amount of disk space, its VDI image filesize is considerably larger. In general, the following three steps will compact your VDI file:

1. Defragment hard drive (in guest system)
   
2. Write zeros to hard drive blocks of free space (in guest system)
   
3. Compact the VDI virtual disk image (in host system)
   

After this process, your VDI file size should be approximately equal to what the guest system reports being in use.

Consider the following example: I run Ubuntu 8.04 as the host system and have Windows XP installed as a guest machine. The corresponding VDI file, winxp.vdi, has a virtual size of 20 GB and an actual size of ~18 GB. However, logging in to the virtual Windows XP system, it tells me that only 3 GB of disk space is in use, while 17 GB is free. How can I shrink, or compact, the VDI file to only use about 3 GB as needed?

1. Windows XP (guest): Run Start -> Accessories -> System Tools -> Disk Defragmenter
   
2. Windows XP (guest): Download and run nullfile-1.02.exe, or run

   sdelete -c

   
   
3. Ubuntu 8.04 (host): Run

   VBoxManage modifyvdi winxp.vdi compact

   
   

Afterwards, the actual size of winxp.vdi is only ~3GB, that is, about 15 GB of free space has become available to Ubuntu.