Today, Hard Drives!
Hard Drives, Hard Disk Drives, what ever you call it, it's an important part of any desktop or laptop computer. Firstly it holds the Computer's operating system, a User Interface that is required for people to operate their PC. There are things that people should know about Hard Drives, here are a few questions I get a lot at work.
- "Why does this External Hard Drive need to use a power supply, and this one just uses a USB cable?"
Well, it depends on what kind of hard drive is inside. There's 3 major standard physical sizes for Hard Drives. 3.5 Inches, 2.5 Inches and 1.8 Inches. Now, if the drive inside is a 2.5 or 1.8 inch hard drive, it can run on 5 volts, the power that can travel down a USB cable. However if it's a 3.5 inch, because of it's larger physical size, it needs 12 volts, and since USB can only pass 5 volts, it'll require a 12 volt transformer/power supply to make it work. At the moment the largest size you can get on a 2.5 inch drive is one terrabyte, and the largest size on a 3.5 inch drive is 3 Terrabyte, though this is soon going to change to 18 terrabytes. When it comes to picking an external drive, you need to think of if you want portability over capacity. - "I bought this Hard Drive at <some date> and it says 1 Terrabyte on the box! but I've only getting about 930 Gigabytes!"
OK, this is more to do with, 1: A confusion in numbers and 2: Something that marketing has created and 3: Capacity used in formatting. Firstly, when it comes to numbers, people have a common perception that 1 terrabyte is 1000 Gigabytes. This is actually wrong, since inside a computer with binary mathematics, a terrabyte is actually 1024 Gigabytes. This is to do with the fact that in binary, you can't get 1000 in a whole binary number, the closest is 1024, so each step in memory, Kilo, Mega, Gigabyte, it's stepped up in 1024s, not 1000s. As for Marketing, You are getting a Terrabyte, but only in the decimal sense, You're actually getting 1000GB rather than the 1024GB. Your Computer sees this and says 930GB because it's calculating 1000GB(decimal) in binary. However, since 1TB in decimal is only 24GB less than 1TB in binary, how does the customer still have an even lower number? This is due to formatting, a hard drive needs a format in order for the computer's operating system to read and write to the disk, it's kinda like having a black board, but some has been nice to give you some chalk and a duster with it too, and that opportunity needs to use up space of the hard drive to work. For Example, remember 3.5 inch floppy disks? Well, a floppy holds 1.4 megabytes of data, but before the floppy is formatted it can hold 2 megabytes, but it need 0.6 megabytes for the formatting in order for the computer to know where the start, middle, and end of the drive is, plus details about how to put information onto the floppy, without it, a computer wouldn't be able to write to it. The same thing happens with Hard drives, it needs this formatting in order for the computer to read and write to the disk, and it WILL use memory to do that. - "What's the difference between SATA and IDE?"
Well, to start off, SATA and IDE are two different connecting cables for hard drives to attach it to the motherboard of the computer. IDE is an older connection, using a broad 40 pin ribbon cable. The highest speed you can get on an IDE cable is 133 Megabits per second; the word "Megabit" and "Gigabit" is used here because that's the measure of travelling data, not capacity, a megabit compared to a megabyte is an eighth of the size of a MegaByte. IDE sends it's data in parallel, think of this as in multiple lanes on a road.
SATA on the other hand is the latest connection. It uses a cable that is a lot smaller than an IDE ribbon cable, and resembles a USB cable in certain ways. There are 3 SATA standards, SATA 1, 2, and 3. The difference between these are to do with speed: SATA 1 reaches speeds of 1.5 gigabits per second, SATA 2 reaches 3 gigabits per second, and SATA 3 reaches reaches 6 gigabits per second. A typical hard drive bought from a computer store will use SATA 2, SATA 1 isn't really used any more, you can find SATA 1 sockets on very cheap motherboards, SATA 2 can work on a SATA 1 socket, but can only reach half the speed due to the limitations of SATA 1. SATA 3 is often used for newer "SSD" drives, which I talk about in the next question. SATA sends data through a cable in "serial", meaning there's only one Input "lane", and one "Output" lane, this may sound like IDE would be faster, but SATA is faster than IDE because it's able to send data very, VERY fast down a single "lane", faster than IDE's multiple "lanes". - "What are these Solid State Hard drives I hear about?"
A Solid State Drive, or an "SSD", is a hard drive is doesn't use a spinning disk inside. Rather it uses a bank of high capacity, high speed chips that hold data the same way that an ordinary Hard drive would. But the advantage to a SSD over a HDD is that because there's nothing mechcanic inside, it's a lot faster, and uses a lot less power than a HDD. However a SSD do not have the same capacities you get on a HDD, a 256GB SSD can set you back over £280! They're not cheap! But they are reducing in price. The current Mac Book Air uses a 64GB SSD, the advantage in this is that since a SSD uses less power than a conventional HDD, you get a better battery time without the need of using a bigger, more expensive battery. As for me, I'm using an SSD in my desktop computer so that I can take advantage of it's blinding speed to load up Windows very quickly, but still use a conventional HDD for everything else such as my music, work and games.
Ok, think I've smeared my brain enough on this blog about hard drives, if you want to know anything else about hard drives, be it internal or external drives. Leave a comment below!
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