Windows 7 - Hard drives

This is a hypothetical question.

How do you make two independent hard drives of the same make, model and volume act as one hard drive?

By having them in an array (RAID/JBOD).

Thanks. Next question; do we have a tutorial on this?

Have a look at this: How to Create a Software RAID Array in Windows 7 - How-To Geek

Thanks for that link. What it is the difference between spanned and Raid 0. I've done some googleing but can't find anything definitive. Are they one and the same?

Here is one definition I found:
That implies that it is not the same as Raid0 (striped) or Raid 5 (mirrored)

Let's imagine that you have a 2 drawer filing cabinet and are writing a series of letters which will be filed in various ways in this cabinet. The drawers represent the drives, and the letters the data files.

Initially, the drawers are completely separate and are independant of one another. Letters may be stored in either one without complications.

Now, let's link the drawers together to form one big drawer. There are 3 main ways that this can be done: RAID0, RAID1, and JBOD.
Let's look at these in order.

Firstly, RAID0. This combines the capacity of the drawers giving an overall capacity of twice that of the smallest drawer. Letters are stored here by being split - odd pages going in the first drawer and even pages in the second. Loss of one of the drawers here results in the effective loss of all of the letters.

Secondly, RAID1. With this analogy, a complete copy of the letter is stored in both drawers, the total effective capacity of which is that of the smallest drawer. Loss of one of the drawers has no detrimental effect on the letters, as both contained a complete copy.

Thirdly, JBOD. Here the drawers can be of different sizes, and the capacity is the sum of that of the individual drawers. Letters are stored in a sequential format, beginning with the first drawer. When that drawer is full, letters are then stored in the second drawer. There are several outcomes here following the loss of a drawer. Obviously, letters stored in that drawer will be lost, but the fate of the others can vary. Depending on circumstances, you may or may not be able to retrieve letters from the remaining drawer.

Color me jaded, but there's very little reason to ever consider RAID0. You won't see the performance benefits that are present in theory, and most often, those who claim to see the performance boost are using synthetic benchmarks, or "just feel like it's faster". It was a fad, and it was debunked and put to bed a few years ago. SSDs may be a little different, but at the same time, the same rules apply...if one SSD is unreliable and fails...you lose your data on both.

Point noted and taken. However, I should point out that I have and still am using RAID0 on my system and was doing so on my previous system without any issues whatsoever. It all depends on your hardware.

It depends little on hardware and mostly on your luck, and how much risk you are willing to take for percieved (not actual) performance gains. My main point is...it was debunked and put to bed years ago, with Anandtech's article still being considered the final word, aka the nail in the coffin. If anyone wants to still run RAID0 on their own, so be it, but I truly think people need to stop short of suggesting or recommending it.