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 and another one will take up for it.
Or number two it will improve access and in some cases we can actually do both at the same time.
Now one raid was developed way back in the day.
The idea was there would be what were known as RAID levels so be RAID 0 RAID 1 Raid 2 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 raid started with RAID 0 0 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 in 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 year how
many drives you want.
And in this case what takes place is that that file has 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 that if I lose any drive I've lost all my data rate zero speeds
things up.
But it provides no data integrity whatsoever.
If you want data integrity one of the things you're going to turn to is RAID 1 that are known as mirroring.
RAID 1 requires a even number of drive.
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 0 provides speed without any data integrity and RAID 1 provides data integrity without any
speed increase in fact RAID 1 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 into do something called a parity.
So let's say I'm got a mathematical formula for say I got one plus two equals three.
Now that formulas 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 parity 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 they will do some magic math to it and create what we call a parity data piece.
Now the first three times they did this was with raid's 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 2 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 parity calculation.
So that way if I lose any one of these three drives I'll still be OK.
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 parity drive.
So raid's 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 Strypes some time too.
And then you would have a dedicated drive that did nothing more than handle parity.
Now they worked out OK in you know years ago I used to see some Raid 3 and raid for 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 and just distribute the parity data out almost all the drives.
And that's where range 5 comes into play.
Range five requires a minimum of three drives.
But in this example we're going to use for 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 say the first chunk 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 parity 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 will put on the first drive and then generate another parity so you can see
it doesn't matter where the parity is because it's distributed across all the drives.
Rain 5 was the most popular form of raid for a long long time.
The downside to RAID 5 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 5 array if you lose one that's fine.
But if you lose to you're in trouble.
So as hard drives get 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 RAID
6.
Now to make RAID 6 work you need a minimum of four drives so let's go and put four drives up here.
Now as we save stuff we're going to do the same thing where we saved 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 parity
but we're going to make two parity 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 raid's 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 0 plus 1 and RAID 1 0
or RAID 10.
Let me show you both of those RAID 0 plus 1 or sometimes just called RAID 0 1 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 that will be work it is the other side of the mirror.
So now when I save something what we're going to do is we're first going to go ahead and Mir that which
means we're going to send that data to both sides.
But then we Strype 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 onto the other side.
So this way what we're basically generating is a mirror of stripes RAID 10 or sometimes called RAID
1 plus 0 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 side 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 rate I want to talk about is what I'm going to call 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 sized
drives you can get real waste issues.
So if I'm doing RAID 5 for example when I have a two terabyte and a 2 terabyte in one terabyte drive
well you might as well just saw the one terabyte off the other two because RAID 5 in and of itself does
not 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 Scientology 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 by Saddam digibox 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 and 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 for Terabyte drives 3.6 Tibbits 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 we go to volume's.
So right now I have a primary array of six drives that are called Volume 1.
You can actually see the six drives right here.
But what I want to show you is right here.
So you see it says Chanology 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.
So knowledge is not the only game in town for this type of thing.
If you're using a more advanced version of Windows you had 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 do too.
Or a combination of two things.
Number one they in crease disk access or they improve fault tolerance slash data integrity.
Using race can be one of the more inexpensive ways for you to help secure data on your system.