External Storage Device Connection Types – CompTIA A+ 220-801: 1.5

| October 3, 2012


External storage devices can connect to our computers through many different interfaces. In this video, you’ll learn about the technologies commonly used to connect our external hard drives and storage devices.

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Review Quiz: External Storage Device Connection Types

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If you’re connecting an external storage device to your computer or your mobile device, you’ll find one of the most common connectors out there is a universal serial bus or USB. The universal serial bus standard has been around for quite some time. And it’s gone through many iterations. So you find USB has a lot of different types of connectors at the end of the cable.

Here’s an example of some of these. One that you’ll find relatively common these days is one called the micro USB connection. This is a plug for a micro USB and it’s relatively standardized, especially on mobile devices because the connection is so small compared to some of these other USB connections.

Now, don’t be fooled because there are a lot of different kinds of very small connectors out there. Sometimes you’ll run into a proprietary connector that looks a lot like USB, but it’s not really. You need to really understand the differences between the micro USB, the mini USB, and maybe something that is in between, that’s not quite a USB standard. Make sure you look very carefully at those plugs.

The mini USB is a little bit larger than the micro, just as the name implies, but not quite as large as something like the Type A. The Type A is that big, rectangular connection that we’re so accustomed to seeing on the back of our computers because it’s such a standardized interface. So you may see a Type A plug or receptacle on your computer and the other end of the cable might be a mini USB or might be a micro USB plug. So you can see these things mix and match along the different cable types,

You’re usually plugging in with this type of plug. This is called a Type A plug. There’s also these larger, squarish looking plugs. You’ll notice that it is curved on one side so it has to go in a particular way. These are Type B plugs.

It’s very common to see a Type A or a Type B on a piece of equipment. These days, if it’s a more modern piece of equipment, it tends to connect to that device through the smaller mini USB Type B plug or micro USB Type B plug.

Another interface on storage devices that you’ll often see is one called FireWire. FireWire is actually an Apple term for this interface. The actual term is IEEE 1394.

You might hear it referred to as i.LINK if it’s a Sony device. Texas Instruments calls this a links connector. They tried to give it a better name than IEEE 1394. So you’ll see a lot of different interface names for exactly the same thing. All of those names, all refer back to the same standardized interface called IEEE 1394.

There’s a lot of flexibility with FireWire. You can actually connect together 63 different devices. They can all be connected together in a daisy-chain mode, a tree format, a peer to peer. You can connect them in any type of way on that FireWire bus. And that bus can reference 63 different devices.

So probably impractical to have that many devices all connected at the same time. But the standard does allow it. The initial FireWire standard that we first saw was FireWire 400. These days we call this Alpha mode FireWire. This refers to IEEE 1394a. So one of the original FireWire configurations.

It ran with speeds that were 100, 200, 400 megabit half-duplex. And that’s an important consideration when looking at the speeds is that initial FireWire 400 was a half-duplex connection. And you can see a couple of the connector types, the larger 6-pin Alpha connector and the 4-pin Alpha connector.

The 6-pin had additional pins so that you could actually power a FireWire device that was connected. The 4-pin Alpha connector does not have power. So that device would have to be powered in some other way, not through the FireWire bus.

The next generation of FireWire was FireWire 800. This is what we now call a Beta mode FireWire. We call that IEEE 1394b. 1894 It ran at speeds up to 800 megabits of full duplex. So we got an increased performance by adding full duplex capability and effectively doubling the speed of that.

And you can see some of the other connectors that you will see in the Beta are things like this 9-pin connection, which also provides power. And that speed is what people really liked about FireWire. You could connect an external storage device and really send a lot of information back and forth between those storage devices.

There are standards in FireWire that can give you even additional speeds, 800, 1,600, even 3,200 megabits per second of full duplex. But due to the declining popularity of FireWire, we never really saw these types of devices ever come to market. These days you will generally see the FireWire 400 or FireWire 800 devices in practical use.

In a previous video, we talked about common ways to connect your storage devices on the inside of a computer. And one of those storage connections was SATA, the serial AT attachment interface. There is also a standard of SATA that was designed to be used for external storage devices called eSATA. And that’s where the “e” comes from, the external serial AT attachment interface.

You’ll see the connections for SATA and eSATA are different. You can’t use the same cable to connect the SATA connection on the inside of your computer and a SATA connection on the outside of your computer. So make sure if you’re using an eSATA connection, that you have the proper eSATA cable.

The protocols that are used between SATA and eSATA are identical. So it makes it very simple for manufacturers of storage devices to be able to create and be able to manage these devices, whether they’re an external SATA connection or an internal SATA connection.

Here’s an external storage device that can connect to our computer either through this USB connection on the back or we can choose eSATA. So if our computer happens to have an eSATA connection, that may be the one to use. Obviously, the speeds that have increased through the years with USB, the USB 3.0 can go at speeds of up to 5 gigabits per second. eSATA, the newest eSATA, goes at speeds up to 6 gigabites per second. So if you have the highest speed of USB or the highest speed of eSATA, you can probably get a little more performance with an eSATA connection.

The ubiquity of USB, it’s see on so many devices, gives us another option however. If we don’t have eSATA, we can at least use this particular hard drive cradle to connect to our computer via USB.

Some storage devices simply use existing ethernet connections to communicate back to our computer. This is an example of a storage device that has hard drives inside of it. It’s a network-attached storage device.

And you can see there are no USB connections. There’s no FireWire. There’s no eSATA on the front of this device. Just a power connection, you’ve got a power switch right here and a couple of ethernet connections.

So you would take your existing ethernet that you’re using in your environment and simply plug it in. You don’t have to have additional ports on the back of your computer. You don’t have to run additional cables. You simply use the existing ethernet infrastructure and communicate to this storage device over the network.

When you’re using external storage devices, one of the options you have is to be able to connect and disconnect those storage devices while your computer is running. That hot, swappable capability gives you an advantage. Because if this was an internal device, you would have to power up your computer, swap out a hard drive on the inside of your computer, and turn everything back on.

If this is externally connected, you have an option within your software to disconnect from your operating system. Then you can unplug it and perhaps plug in another storage device. USB drives provide a very common capability to be able to do this. USB certainly allows you to turn off that connection in your operating system and simply unplug it and plug in another device if you’d like to.

FireWire is another way to do this. While you’re running with your computer, it’s very common to connect and disconnect FireWire storage as well. And of course SATA and eSATA are additional standards that allow you for some hot plugability, some hot connections.

Whether it is a storage device like this with an internal SATA connection, you’re able to unplug that connection in a SATA environment, because SATA was built with the capability to do that a hot plug and hot unplug capability for swapping that drive out. And eSATA of course, being external, you’ve got access to your connection right there. You can unplug your connection on the fly and plug in to other storage devices as well.

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Category: CompTIA A+ 220-801

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