I have been in the computer industry for over 15 years now. I have been to almost every Comdex and CES that you could go to. I have been spending many hours over the last decade thinking about technology and studying it. This will be the first of many blog entries with the name Computer Entry in front, in these entries I will talk about the world of the computer. It may be interesting or very boring depending on where you sit. My target audience is the business owner, not the techie. I will share what I have told hundreds of clients, in an easy to understand format. It will start basic and get more complex as the blog goes along.
THE HARD DRIVE
The hard drive is a small disk that is inside your computer, it is used to hold data for long term storage. (Contrary to what many customers think the hard drive is NOT the tower that you see.) The hard drive is also not your RAM even thought it has random access. Your computer has two main types of memory. First is your RAM, RAM is fairly fast, directly connected to the motherboard, and requires power at all times, even it is the working, short term memory. Your hard drive is about 1% the speed of RAM, it only uses power to read or write data and is MUCH larger than your RAM. You hard drive is where all of your files and programs are stored. The hard drive stores data on metal disks called platters. These work much like you would imagine a record player working with a read/write head on the end of an arm that swings back and forth, it is moved by changing a magnetic field at its other end. On each disk there are thousands of tracks, these are not viable but only magnetic. Along each track the metal is charged by a small magnet on the tip of the write head, the charge will stand for either a 1 or 0.
The first hard drive I used in my first computer was 4 inches tall and 6 inches wide, it was about 10 inches deep. It had 4 platters, each side of each platter was used and contained a whole 4MB of data, for a total of 32MB. The year was 1988. There were a hand full of companies that constantly worked to make the drives smaller, faster, cheaper, quieter, more robust, and most importantly contain more data. Every month a new drive was released that would set a new standard, a trend that is still true today. By 1995 I purchased a drive that was only 3.5 inches wide and 1 inch tall, the same size standard for most of todays drives. It was much faster than my old drive and held 540MB of data. It also used the new IDE interface. Every few years a new standard would come out for communicating the data from the hard drive to the motherboard, but by far IDE was the longest serving, most widely used standard. Not until 2006 was it surpassed in usage by SATA. Sata2 is now the main standard, it is faster, uses less power and has a very small wire which is nice for airflow. We put this type in all of the computers we build.
When it comes to hard drives people really like to focus on speed. Unfortunately the total speed of a hard drive is a complex formula that is very hard for most people to understand, so many people look at just part of the formula and often get misled. The interface used to matter for speed but for now SATA2 is so fast that it is faster than all drives that exist so the interface no longer matters. Lets think about it in easy to understand terms. It is made up of three basic things. First you need to know how fast the arm can move the read/write head. Because you are always moving to and from different locations they take the average and give you that rateing. Usually it is from 3-10ms. The faster the better. Once you have moved the head to the right location you need to wait for the disk to spin and the data you need to move under the head. It could be 1% away or 99% away or anything in between, so most people use the number for the disk to spin half a rotation. The faster the disk spins the shorter this time will be, and also the faster the data will go under the head.
Many people stop here when they shop. They only look at RPM and Random Access Time and think that will tell them how fast their hard drive is BUT they are VERY VERY mistaken. Even high level tech people are fooled by the most important part of a hard drive. That is how dense the data is that is on each track. If you are dealing with very small bits of data it does not matter much, but today most people deal with very large files, you may have to spend a second or two reading one file. There is a drive out there called a Raptor, it has a very fast arm and it spins at 15,000 RPM BUT it only holds 74GB of data on two sides of two platters, the data density is very small by todays standards at 18GB per side of a platter. Now we can take the standard 320GB hard drive that our company uses on our basic computers, it has a slower random access time and spins at only 7200RPM, BUT it uses only one platter, with 160MB on each side. So the Raptor will find the data much faster but the “Slower” hard drive I use reads it 5 times faster once it is found, it only takes a few 100k of data and my drive is now faster. For a large file, or files that are stored in the same order they are accessed my drive smokes the Raptor every time. For many small files the Raptor wins. The Raptor is much louder, much hotter and for 1/4th the space it costs 3 times the price, not a good deal for anyone I know, but their marketing sure sells hard drives.
Another thing you need to think about is gyroscopic forces. You have a metal platter spinning at a rate over 140 times per SECOND. Anyone that has played with a gyroscope will tell you that when you move a spinning object in one direction it will push in another. If the head is over the part that bends the platter could crash into the head and scratch the platter, this what they mean when a drive crashes. To avoid you need to avoid moving a spinning hard drive. Now this is harder than it sounds when you consider many people have a laptop as their main computer. Because of this laptop platters are smaller and spin much slower and they also have a lot of shock absorbing. Some even have features that sense a fall or too much movement and quickly move the head off of the drive to prevent a crash. Even with all of this I am still very careful with moving a laptop too much, and I always back up data from a laptop.
Now everyone has heard about defragmenting your hard drive. What is this all about? Well sometimes, in order to fit the data on the drive the hard drive spits up the file into separate pieces. It is still one file to your os but it is stored in many different fragments, this really hurts speed because for you to read that file you have to read ever piece. If there are 100 fragments it could take a few seconds. Back in the days of DOS and Windows 3.1 it would write the data in the first open slot and was always fragmenting the drive. Each newer OS puts more and more safeguards in place to try to keep this from happening. Now with Vista this problem is almost gone.
I will leave you with the info on the my newest hard drive. It is the first Terrabyte hard drive to only use 3 platters, each with 160MB per side, the highest you can buy. It is 7200 RPM, very quiet and HUGE. Samsung really did a great job on this drive. This drive cost only half the price of that drive I told you about from back in 1995. Impressive how far we have come.
Thanks for reading. For more tech stuff on hard drives go here.