An Overview of Storage Devices – CompTIA A+ 220-901 – 1.5

| November 29, 2015

There seems to be a different storage device type for nearly every application. In this video, you’ll learn about optical storage formats, hard disk drives, solid-state drives, hybrid drives, hot-swappable drives, flash memory drives, and tape drives.

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Our computers wouldn’t be much good to us if there wasn’t a place to store the documents that we use every day. In this video, we’ll look at some of the storage technologies that are used in today’s computers.

One common storage type that you’ll find is optical storage. There are so many different kinds of optical formats for saving information, but they all work basically the same. There are very tiny bumps on these optical devices, and we read these bumps using a laser beam. This is a very microscopic way of storing information, but we’re able to store a great deal of that on a very small area. For example, a CD-ROM, which stands for Compact Disc ROM, can store up to 700 megabytes of data.

It gets even bigger when we look at a DVD. The DVD read-only memory– and DVD stands for Digital Versatile Disk– can store up to 4.7 gigabytes on what we call a single layer DVD. And we double that for dual layer DVD to 8.5 gigabytes. One of the more recent optical formats is Blu-ray. And a Blu-ray disc can hold up to 25 gigabytes on a single layer Blu-ray. And a dual layer Blu-ray can hold up to 50 gigabytes of information.

Many of our computers can not only read from an optical device, that can also write to an optical device. When we’re writing to these devices, we use a little bit of a different format. Unlike the commercial devices that create bumps on the optical disk, these devices on our computers simply burn a small area of the disk, making it a little bit darker on the photosensitive dye that’s on these disks themselves. The types of formats you’ll see are compact disc rewritable. And you can see there is the CD-RW abbreviation, the RW standing for the ReWritable.

A DVD can also be burned with a DVD read and rewritable, and you’ll see that abbreviated as DVD-R/RW. There’s also a dual layer version of this, which is the DVD-R DL. Blu-ray discs can also be recorded to with the Blu-ray Disc Recordable, which is the BD-R. And you can even erase and record over that with the Blu-ray Disc Recordable Erasable.

Optical discs are a useful mobile type of storage. You can move it around very easily. But sometimes we need a lot of storage inside of our computer, something that will always be in that particular system. And in those particular cases, you may want to have a hard drive. A hard drive consists of some spinning platters that are inside of a device that is moving very quickly.

Here’s a good example of how quickly this is spinning inside of that hard drive case. I’ve taken the top off of this one, which is something you would never want to do. That should always have the cover on top of the hard drive. But those platters inside are spinning very fast. For example, the rotational speeds can range between 5,400 revolutions per minute up to 10,000 revolutions per minute, and even faster in larger data center environments. When you’re spinning the drive faster, you’re able to access the information faster. So generally, the faster drives tend to have the lower latency to be able to grab data off of that device.

Let’s look at more detail of these different components inside of the hard drive. We first have these spinning platters that are spinning around this spindle. And we have to have some way to pull information off of these platters. So we have an actuator here on the left side that is connected to an arm. And it is able to then actuate or move the arm back and forth across these spinning platters. At the very end of this arm is a read-write head. That is what’s used to read and write the magnetic information from these spinning platters.

Here’s a side view of what you might see. You can see the arm is coming off the actuator. The head is right here at the end. And these platters are normally spinning around very rapidly, and the head is moving back and forth. There are multiple heads. You can almost see them underneath here. So we’re able to read and write from all of these platters at the same time as this drive is spinning around inside of a hard drive enclosure.

A hard drive is a very large storage device, but it is limited by the speed at which we can receive and send information to that device. And it is a mechanical device that ultimately will break. The SSDs are designed to replace some of those shortcomings. An SSD is a Solid State Drive. These SSDs are all memory. It’s effectively flash memory in a component that connects to your computer for long-term storage. Because it’s memory there’s no moving parts, so you’re able to access information very quickly. And of course, there’s no moving parts to wear out.

If you were to combine a traditional hard drive and an SSD together, you would get a hybrid drive. A Solid State Hybrid Drive, or SSHD, has both a spinning drive inside of it, the traditional hard drive, and it also has SSD flash memory combined as well inside of a single device. The SSD on a hybrid drive is not necessarily there to store information over a long period of time. Instead, it is used to cache information as we are writing to the hard drive or reading from the hard drive.

Because SSDs tend to be much more expensive than a spinning hard drive, we’re able to get some increased performance by including a smaller SSD in a hybrid package, thereby getting better performance but not having the overall cost of an SSD. If you were to look at a hybrid drive, it looks very similar to a traditional hard drive. There are spinning platters inside, and the SSD memory simply attached onto the same form factor you would have as a normal hard drive.

If you’ve worked with hard drive arrays before, you’re probably familiar with hot swappable drives. A hot swappable drive is one that you can remove or insert into a computer without having to power down anything. It’s a hot connection, so you’re able to plug and unplug whenever you would like. There are many different ways to do this. One common type of hot swappable drive is a USB drive. We can have an external USB drive that is connecting to our computer with a normal USB connection. And when we’re finished using that drive, we can simply disconnect it with the USB cable.

Another common hot swappable drive type is a FireWIre drive, where we’re able to connect and disconnect using a FireWire cable that’s external to our computer. And part of the SATA standard provides for a hot-swappability. You often can see that if you’re working with hard drive arrays and you’re using SATA drives for that. You can simply slide them into the array or disconnect them from the array in real time as the entire system is running. The SATA standard also includes eSATA. That stands for external drives where you have an external cable connecting to an external drive array, and that also is a hot swappable drive type.

One very popular storage type is the USB flash drive where we’re able to store a large amount of information in a very small portable package. This consists of flash memory, which is EEPROM memory, Electrically Erasable Programmable Read-Only Memory. A flash drive is non-volatile memory. That means that you don’t have to constantly provide power for it to store information. So you can plug in your USB drive, copy information to the drive, unplug it, and you don’t have to keep it powered as you’re moving it from one system to another.

One challenge that we have with flash memory is that it only supports a certain number of rights to these storage devices. At some point, we would not be able to make any more rights to this flash memory. We would still be able to read the information. We would just not be able to change anything on that drive.

Although these USB flash drives are very small and very mobile and they store a lot of information, they’re not very good to use for archival purposes. They’re very easy to damage and certainly easy to lose, so you want to always be sure to have a backup of everything you’re storing on that flash drive.

There are many different kinds of flash drive formats, so I put them all together and made a picture simultaneously so you could really get an idea of the scale between the different flash formats. You’re of course probably familiar with the USB flash drive format. One format that’s been around for a number of years is the CompactFlash format, the CF format. You can see it’s relatively large, especially when compared to the other formats that are here.

The Secure Digital is a popular format today, the SD card. And there are different types of SD. You can see the mini SD and the micro SD that you might find in some very small mobile phone devices these days. Some of the older digital cameras use an xD-Picture Card format like the kind you see here. And if you have a mobile phone or another mobile device, the flash memory type inside of that device is probably going to be eMMC memory.

It’s important to have storage types that allow us instant access to the data. But what if you need to archive data over a very long period of time, and you’d like to do that for a lower cost? One good way to do that is with a tape drive. These tape drives store information on these magnetic tapes. These tapes are used to store information sequentially, which means we’re going to write information to the tape, then the next file will be written to the tape, and then the next file will be written to the tape, and so on. If you need to access a file that is somewhere down the tape, you would have to fast forward through the tape to find the exact point you need to be able to read that information off. And then, of course, rewind to another area to read it from a different file.

There are many different kinds of magnetic tapes and tape drives. They can range from 100 gigabytes in size to multiple terabytes on a single tape cartridge. These tapes make for a very inexpensive way to store large amounts of information over a very long period of time. They are relatively inexpensive to purchase. You can store them and ship them very easily. And if you ever need to get that information, you simply put the tape into your tape drive, go to the exact place on the tape, and restore that file.

One very common open standard that is used for these tapes is something called LTO. That stands for Linear Tape Open. You may also see this referred to as the Ultrium form-factor. And if you’re working with tapes and tape drives, you’re probably going to use an LTO tape format to store some of your information.

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Category: CompTIA A+ 220-901

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