Greetings,

I had the idea of installing a Linux (or BSD) distro to an external, portable, USB hard-drive and then plug it into a pc and use the external hard-drive with OS as the pc's OS. Will this work? I have never tried this before. If it does work, is there any special way I would have to set this all up, configure everything and then use it, or would it pretty much be a simple and easy "plug-and-play" affair?

Thanks

Putting an OS on an external hard-drive is easy. Just be careful where you put the boot-loader.

Install should be the same as if it were going on an internal drive. If you want to boot your distro on any machine, make sure to put the bootloader on that external drive also, and use UUID instead of /dev/sdxX.

To most modern linux/bsd a usb drive is the same as an internal drive. While I'll agree that usually a live to usb app creates a slightly faster install I prefer to use a real install. The live to usb tend to save a compressed filesystem. A new fast usb is plenty good for most uses. A fast usb 3.0 with supported OS is really nice.

In a odd twist, the newest linux tried to add in some features and got complex in respect to video drivers. It is possible to disable those features but you may not get full video ability.

If you were to just use this usb on a single machine you could fine tune it for it's hardware.

Look up 'pen-drive linux'.

a few caveats would be that USB is inherently slower than even IDE let alone SATA, though not necessarily a problem with simply booting an OS, it can be really apparent when doing something more intensive such as swapping onto a USB drive.
secondly, if this is a hard drive, than it shouldn't be any different than an internal hard drive (assuming the BIOS supports booting from a USB device, though this is pretty much standard in modern units), if it is a flash device though, you have to remember that flash devices wear out faster than hard drives with heavy use

either way you may want to use a bootloader/filesystem better suited for USB drives rather than the standard, but the standard should work just fine, albeit perhaps not as optimally as it could.

USB 2.0 is reasonably fast; FireWire is much faster. Many computers have the ability to run FW800 or better, and disk enclosures can support both. (Some enclosures also provide ESATA.)

I use external drives for a variety of things, including the system-volumes of virtual Linux machines. And, to my way of thinking, "virtual is the only sensible way to go" these days. Leave the host, whatever it is, entirely alone, and run VMs. Intel microprocessors now have very sophisticated support for virtualization in hardware. When you point a VM at a fast external drive, you don't have to do anything to the host ... which is usually a good thing.

USB 2.0? Firewire? What is this, 2008? Firewire is long since dead and USB 3.0 has been integrated into the motherboard of basically every system sold in the last 2-3 years. USB 3.0 is significantly faster than Firewire, IDE, SATA I, and SATA II, the only thing faster is SATA III, and SSDs are the only devices capable of saturating that bus.

I dare you to find a practical difference in usage speed between a drive (even an SSD in anything other than sequential benchmarks) on SATA vs USB 3.0.

reasonably fast for normal operation such as web browsing, watching videos etc.. though the boot process will be noticibly slower (though not unreasonably so). the real bottle neck is putting swap space on the USB drive, since swapping is slow even with a SATA drive, you'd have to be a massochist to use swap space on a USB2 drive.

you should look into live-usb.

if you are planning on using this on one (and only one) machine you could just install the os to the usb drive (and install the wifi/sound card/graphics adapter/... drivers for that particular system). it should be the exact same process as installing to any other harddrive.

Look here:
http://64.124.13.3/hacks/USB_Boot_using_GRUB.html

I've done this a couple times with my laptop. Loading the ramdisk always seems to take the longest during the boot process.

Having a fast USB drive helps. I have a PNY Mini Attache 16GB, and it's not horrible. I also have a PNY Micro Attache 32GB, and it's horribly slow.