The Multi-OS system
I remember in the old days, you installed one OS on a single computer, then later, you were able to dual boot 2 OSs on one machine. In my mind, that was as far integration could go. In recent year I seen changes in system integration that required an individual to master innovation. I give thinks to Virtual Machines for forging a new path into system interoperability ,and also, to the birth of Linux.
I have been using linux for a while and benefited much from its value. It has taught much about the inner-workings of an operating system which is invaluable for a system administrator. The best part is, there are more than one flavor of linux OSs that have their own defined functionality.
Most of these linux distros are custom made, adding more features and optimizing speed. This was done at someone's discretion for a more friendly like system. With time and efforts committed, they compiled a decent OS that lots of people find useful. Most linux distros come installed on a liveCD which is great for testing. Once you find the preferred OS, it's off to installation.
If you have a desktop or laptop, you could try out these custom made distros by simply dual booting using a boot loader like lilo or GRUB, or simply, install the distros on their own harddrive. Grub allows 2 OSs to co-exist. Lilo can be tweaked to boot multiple OSs detected on you machine. Lilo, unfortunately, has some glitches and is not something I would rely on. Choice in convenience, I wouldn't think anyone wants to constantly open their computer cases and keep installing different harddrives or have perform a re-installation.
Currently, a linux enthusiastic or administrator, wanting to tinker with multiple linux distros will install them on a virtual machine and try them out on their primary OSs: Windows, Mac OS and linux.. This I highly recommended. There is, however, another option if dual booting and virtual machines aren't enough. How about a multi-OS harddrive?
A multi-OS hard drive is simply, a hard drive with multiple partitions that will be used to install OSs. Similar to a dual boot setup, you section the hard drive into multiple partitions, or how many the particular partition manger will allow you to make, and choose a partition to install your preferred OS. Simple, It gets better.
Once you have all the OSs installed, simply toggle the boot-flag value to the partition with the OS to startup during system initialization. To toggle the boot-flag value, Open a terminal, type: # sudo fdisk /dev/<ID of harddrive> and use the option “a” to switch the boot-flag value to the required partition. Write the changes, and restart the system. When your linux system boots up, it will look for the partition with the boot-flag and load the OS within that partition.
There are some disadvantages to this unique setup. Because the system is not using the first partition on the drive, access time will be increased. I have noticed that when I open a program or window in my Slackware system, it would take a couple of seconds for the program to load or the window to open. The wait time is not excruciatingly slow, so it's not much of a big deal. For those, however, who like “fast”, this is something to think about. Most of these OSs I'm just testing, so I'm not too concerned about speed.
Another neat little thing you can do, if you have more than one harddrive installed, you can enter the system Bios, and select the harddrive to boot from. I find this useful with my windows Vista harddrive. One if the reasons, I was unable to re-size the partition to install Ubuntu. All I do is select the hard drive with vista installed from the boot order menu in Cmos, and make that drive the first drive to boot. How cool is that. Another option is to have a second CD-ROM installed on your system and insert a liveOS and use that to boot to a commad prompt and select the boot partition from there.
When you partition the harddrive using fdisk, you are only able to have a total of 4 partitions. Even if it is “extended”, you are still limited to 4 partitions. Remember you need one partition for swap. Other partition programs could allow more partitions to be created, so there are workarounds.
At the end of all the tweaking, hacking, installing and messing around, you have yourself a multi-OS system that will allow you to choice what OS to load by simply pressing a button or at the click of a mouse.