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RAID

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Transcript

A random array of independent devices better known as raid has been the primary way that we provide security to our stored data on our systems. Now, raid is an old idea. It's been around for over 25 years. But basically the cornerstone of raid simply says this. Instead of just using one hard drive to do something, I can use multiple hard drives that will work together to act as one hard drive to do one of two things, either number one, they're going to provide some form of data integrity, if one drive dies, another one will take up for it. Or number two, it will improve access.

In some cases, we can actually do both at the same time. Now, when raid was developed way back in the day, the idea was there would be what were known as RAID levels, so it'd be raid zero, raid one, raid two like that. And each one of these RAID levels define a specific way to do this. So let's march through all the different versions of raid starting with raid z. raid zero, better known as striping is designed to do one thing, and that is to increase the speed that you can get data. Now it does this by dispersing a piece of data across multiple drives. So normally here I've got a Word document.

Normally, I would just go ahead and chop that up into individual clusters and each one of these clusters would be saved to one hard drive. But with striping, what we do is we could use two or three or however many drives you want. And in this case, what takes place is that when that file is saved, one cluster is saved on one drive another cluster on another and another on another. So you have to have a minimum of two drives to do this. striping really speeds things up because we're not waiting for one hard drive. However, the downside to striping is if I lose any drive, I've lost all my data.

Raid zero speeds things up, but it provides no data integrity whatsoever. If you want data integrity, one of the things we're going to do To is raid one better known as mirroring, raid one requires a even number of drives. So in this case, let's just use two hard drives. Now what we're going to do is we're going to save that word document again. However, this time, what we're going to do as we save the Word document, each individual cluster is copied or as we say, mirrored to the other drive. Now, raid zero provides speed without any data integrity, and raid one provides data integrity without any speed increase.

In fact, raid one slows things down because you got to do everything twice. So now we've got a challenge, we would like to speed things up. but on the same token, we'd like to have data integrity. So to do that, we have a number of different RAID levels that introduce something called a parity. So let's say I've got a mathematical formula. Let's say I got one plus two equals three.

Now, that formula is easy to do, but if I lost any one part of this formula, it would be trivial for someone mathematically to figure out which part isn't there. So if I lose the one, I know something plus two equals three, and mathematically, I can figure out what that is. That's kind of how parody works. So what we do in this situation is we will save one chunk of data, then we'll save another chunk of data, and then we'll do some magic math to it and create what we call a parody data piece. Now, the first three times they did this was with RAID levels, two through four, let me show you how they did it. So let's take that same word document and this time we're going to apply raid, we'll call it just raid two for the moment.

So I'm going to use a minimum of three drives to do this. So what I'm going to do is I'm going to go ahead and start saving that document. So I'm going to put one cluster on the first hard drive. Then I'm going to put the second cluster on the second hard drive. But on the third hard drive, I'm going to go through this parody calculation. So that way, if I lose any one of these three drives, I'll still be okay.

Now. If I keep saving, I'm only putting data on the first two drives. So that third drive is nothing more than what we call a dedicated parody drive. So raids, two, three and four pretty much did this all exactly the same, what you would have would be two or more data drives that would store the individual pieces of data, we call it stripe sometime to and then you would have a dedicated drive that did nothing more than handle parity. Nothing worked out. Okay.

And, you know, years ago, I used to see some raid three and raid four solutions. But what we settled on was a more interesting and more unique idea. And that is, instead of having one drive that is just for parity, go ahead and just distribute the parody data out among all the drives, and that's where raid five comes into play. raid five requires a minimum of three drives, but in this example, we're going to use four just because you can use more than three if you want to. So here's my Word document one more time. Now what I'm going to do is I'm going to save the front Jump to the first drive.

I'm going to save the second chunk to the second drive. And what I'm going to do now is I'm going to stop and I'm going to generate a parody value. So now I've got the third chunk to save, we'll go ahead and put that on the fourth drive. And then the fourth piece, we'll put on the first drive and then generate another parody. So you can see, it doesn't matter where the parody is, because it's distributed across all the drives. raid five was the most popular form of raid for a long, long time.

The downside to raid five is that you can lose one drive, but you can't lose more than one drive. So if you've got four drives that you're using as a raid five array, if you lose one, that's fine, but if you lose two, you're in trouble. So as hard drives got cheaper and cheaper and it became easier to use more and more drives, it started to be a good idea to go could we come up with a way to do this, where we could lose two drives and that's the beauty of rates. Now to make raid six work, you need a minimum of four drives. So let's go ahead and put four drives up here. Now as we save stuff, we're going to do the same thing where we save one piece, then we save another piece.

But here's the big difference. This time, what we're going to do is we're not going to make one parody, but we're going to make to parody so and we'll distribute each of those on separate drives. Now, what you're looking at is that you could lose any two of these drives, and you can still recover all the data. So raids zero through six are our basic RAID levels. However, you can do some interesting things with raid and what we call hybrid levels where you can combine two of these. So probably the two most common that we're going to combine are known as raid zero plus one and raid one plus zero or raid 10.

Let me show you both of those raid zero plus one or sometimes just called raid 01 is basically a mirror of stripes. So to do this We're going to need a minimum of four hard drives. So we're going to have these two hard drives that are going to be working as one side of the mirror. And these two hard drives will be working as the other side of the mirror. So now when I save something, what's we're going to do is we're first going to go ahead and mirror that, which means we're going to send that data to both sides, but then we stripe it within those drives. So if I've got this one chunk of data, I'm going to put two stripes on one drive.

And then I'm going to mirror those two stripes on to the other side. So this way, what we're basically generating is a mirror of stripes. raid 10, or sometimes called raid one plus zero is a stripe of mirrors as you might guess. So let's use the same setup we had before. And this time, what we're going to do is we're first going to go ahead and take our piece of data and we're going to stripe it however that stripe gets mirrored between each drive. So we get this one piece of data.

We go ahead and stripe it. So this is gets the first stripe. And then this side gets the other stripe However, it's mirrored between the pair drives. Now the last type of raid I want to talk about is what I'm going to call a proprietary raid. There are a lot of folks out there who say there are problems with the established RAID levels, and they can do it better. Well, they're absolutely right.

For example, one of the big problems with established RAID levels is that if you don't use the same size drives, you can get real waste issues. So if I'm doing raid five, for example, and I have a two terabyte and a two terabyte and one terabyte drive, well, you might as well just saw the one terabyte off the other two because raid five in and of itself doesn't know how to handle that. So that's where these proprietary protocols come into play. In fact, I use one here at total seminars. I use a very popular type of box called Synology boxes. Let me get a picture of it up here for you.

Aren't those pretty? And these boxes are just filled with drives. So the cool part to these is that you actually access them through a web page. And I've got that up here. Let's take a look at this. So this is my Synology box.

And he's just another computer on my network. So what I'm going to do is I'm going to head over to the Storage Manager. Give him a moment to do his thing looks like everybody's happy. Now, you could actually look here right now I have six physical drives stored in one of these. And then there's a backup device that I backup to. With another six here, there's room for six more.

So what I want to do is first off show you the hard drives. So you can see here's my six drives, and they're actually four terabyte drives. 3.6 Tibbets, but they're all looking good, everybody's happy right now. And these are the backups. Now, what's actually kind of interesting is when I go to volumes, so right now I have a primary array of six drives that are called Volume One. You can actually see the six drives right here.

But what I want to show you is right here. So you see it says Synology hybrid raid that's their type of raid with protection for two disks fault tolerance. So these types of proprietary raids are very popular, they work great Synology is not the only game in town for this type of thing. If you're using a more advanced version of Windows, you have the famous storage spaces, which is an amazing tool when it comes to proprietary raid technologies. The important thing, especially for the exam that I want you to keep in your mind is that different levels of raid due to or a combination of two things. Number one, they increase disk access, or they improve fault tolerance slash data integrity.

Using raid can be one of the more inexpensive ways for you to help secure data on your system.

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