You are a young go-getter who wants to be in the business of IT. Looking at the market you see that enterprise class storage companies are growing both in sales and product offerings, and you decide to pursue storage technologies as your area of expertise. You dedicate yourself to the pursuit of knowledge on all matters of Storage Area Networks (SANs), Network Attached Storage (NAS), and Storage Virtualization.

That is an awful lot of technical material to digest! Where should you begin in your pursuit of enterprise class storage mastery?

The answer? Learn how a hard drive works.

I know that it is not sexy. It is the exact opposite of sexy. It is not innovative nor cool to say “I know how a hard drive works!”

But if you do not understand how a hard drive works you do not understand the fundamentals of data storage. You have to crawl before you can walk, walk before you can run, and run a lot of miles before you can attempt the marathon known as enterprise class storage.

So I’ll cover the sexy bits later in future articles. Right now, let’s focus on the lowest common denominator for enterprise class storage solutions: the hard drive.

First Things First – What is a Hard Drive?

Technically I should be starting this series of articles with “what is the binary system”, but I believe that the hard drive is the better place from which to start learning about storage. The hard drive is a physical component where data is written too and read from when that data is not already available via the computer’s Random Access Memory (RAM) modules (memory will be covered in a future article on computer basics). Unlike RAM the hard drive is capable of providing for the long term storage of data.

In most cases the hard drive is a series of metallic platters that are stacked on top each other and mounted to a spindle. Recently Solid State Drives (SSDs) have emerged that use forms of Non-Volatile RAM (NVRAM) with which to store data, but there is data that suggests SSDs to be a limited technology. That is why I am going to focus on the good old platter based hard drive as it is a very common storage device that is still likely to be used for quite awhile (but you never know what the next technological breakthrough will bring us).

How Does a Hard Drive Store Data?

Essentially a hard drive records magnetic patterns onto a metal spinning disk. Understanding the underlying physical operations of a hard drive though is essential to properly sizing and designing enterprise class storage solutions. A small mechanical arm moves above the metal platter, and a small read/write head is held slightly above the spinning platter by this arm. Typical hard drive designs use several

platters and they read/write data to both sides of those platters. The speed of the arm’s motion from the edge of the platter to its center and back, the maximum number of Revolutions Per Minute (RPMs) that the platters can spin at, and the number of tracks and sectors that each platter holds all influence the capacity, reliability, and performance of a hard drive.

When a hard drive spins the heads on the arm move slightly above the surface at an incredibly high speed. The heads use magnetic pulses to leave a magnetic signature on the individual sectors and tracks. Although there are different standards for writing the data to the hard drive all of these methods are built upon the binary system. So the head is essentially writing and reading just two things from the disk: a zero or a one.

But How Does This Help Me Understand Enterprise Class Storage Solutions?

Whether you use a SAN or NAS your hard drives are the building blocks for the rest of your storage solution. For instance, if your objective is to improve the speed at which your system performs then upgrading the network used to attach to the storage and the controllers that interface between the system and the storage may not improve your performance at all. If the storage system has slow hard drives or not enough hard drives to meet the performance needs of your environment you cannot expect improvements from upgrading other components of the storage system first.

This is not to say that the answer is always “More faster and bigger hard drives.” The point is that you need to think through your storage design from the highest level down to the lowest components in order to make the best design decisions that will maximize the return on your storage investment.

This Is Just the Tip of the Iceberg

What I have provided you with here is a very basic overview of how a hard drive works. This is nothing more than a glimpse at the many components that comprise a hard drive, and keep in mind that hard drives keep getting larger and faster. The physical components as well as the protocols and methodologies used to store data keep changing.

This is a good problem to have though, because it is much better to have to keep up with rapidly evolving technologies than to find yourself an expert in a stagnant technology. I suggest that if this article piqued your interest that you keep researching how hard drives work on your own. All you need is a good search engine and the tenacity to keep asking questions until you find the experts who can answer them for you.

Thanks for visiting my site and reading this article. If you have any questions please ask by leaving a comment below. Meanwhile I will be working on more articles, including a follow-up article to this one that focuses on Redundant Array of Independent Disks (RAID) technologies.