-: In this lesson, we're going to discuss the use of RAIDS
to ensure your data redundancy.
You first learned about RAIDS
all the way back in your A plus studies.
If you remember a RAID is a redundant array
of independent disks
which is essentially going to allow you
to combine multiple physical hard disks
into a single logical hard disk drive
inside of the operating system.
Now, for the security plus exam
you need to know about a couple of RAID types
including; RAID 0, RAID 1, RAID 5, RAID 6 and RAID 10.
A RAID 0 provides data striping across multiple disks
and is used to increase your performance.
The key word here is striping.
For example, you might use a RAID 0
when you need performance, but you don't care about
fault tolerance, so a good example of this is
I do a lot of video editing and so I really care about
performance there as I'm editing these raw videos
and so by having these two drives working together,
I can do things much quicker
than I could with a single drive.
Now to do a RAID 0, you do need at least two disks
to work in tandem with each other.
The next one we have is a RAID 1
and this is going to provide redundancy
by mirroring the data identically to two hard drives.
So if one drive fails,
the other can continue to operate
because it has a full copy of everything that was on there.
This provides the least amount of downtime
because there is always that complete copy of data
ready at a moment's notice to take over.
This provides wonderful fault tolerance,
but it can it can only be used with two physical hard disks
and that provide you with one single logical hard disk
inside the operating system.
A good example of this is once I'm finished
editing all my videos
and I have the final the final product,
I want to make sure I don't lose it,
so I can actually move that over to a RAID 1
where I get two identical copies of that file
one on each of those drives.
Now, the next one we're going to talk about is a RAID 5.
A RAID 5 is known as a striping disk with parity.
It requires at least three physical disk drives to work,
and it provides fault tolerance
by striping the data across multiple disks
and writing parity data to the multiple disks too.
If one disk fails, the other two can reconstruct the data
based on the parity and they continue to operate.
This means that if one of those drives fails,
I can pull it out,
put in a new drive
and it will rebuild itself inside the RAID
as it keeps moving and operating for the rest of the system.
Next, we have a RAID 6
and a RAID 6 is a modified form of a RAID 5.
In fact, it's one better than a RAID 5
that's why we call it a RAID 6.
Now, it's going to use data striping across multiple disks
just like a RAID 5 did,
but instead of having one stripe for parity data,
it's actually going to have two stripes for parity data.
This requires another disk in the array to work
so you need at least four physical disks,
but that does provide you additional fault tolerance
because you can lose up to two of these four disks
and the RAID will still continue to function.
The last RAID we have is known as a RAID 1 0
which is written as RAID 10.
This combines the advantages of a RAID 1 and a RAID 0
because one plus zero equals 10.
This requires four physical disks just like a RAID 6
and it's going to provide you with a redundant mirror
of striped drives and its fully fault tolerant.
This gives us all the speed of a RAID 0
by splitting up the load across two sets of RAIDs,
but it also gives us the full redundancy of a RAID 1
by having those two RAID 1 in there.
Now, this all works as one combined logical drive
even though it uses those four drives
split up into two pairs of two.
So, when we think of RAIDs, they can be categorized as;
failure resistant, fault-tolerant and disaster-tolerant.
These are our three categories for RAIDs.
Now, if you have a failure-resistant RAID,
that's going to be something like a RAID 1 or a RAID 5 because
it's going to protect against the loss of the array's data
if a single disk fails inside of it.
Now, we talk about fault-tolerant disk systems,
this will be something like a RAID 1 or a RAID 5 again,
or even RAID 6, because even if a single component fails
one of those drives or even one of the cards inside of it,
then that RAID can continue to function properly.
Now, our final category is known as disaster-tolerant,
and so if we call a RAID disaster-tolerant,
this means that the RAIDs has two independent zones
with full access to the data at all times.
A RAID 10 is a good example of a disaster-tolerant RAID,
but so is a RAID 01.
A RAID 01? What's that?
Well, if I create this RAID 01,
I'm going to have a striped array
made up of two mirrored RAID 1, and by doing this,
I could lose either half of the array
and one of those RAID 1 are going to still function,
and that means the system is still going to keep functioning
and is going to make it disaster-tolerant
because I have a full copy of that data
ready to go at all times.
Now RAIDs are a great thing to use
when you're trying to ensure you good redundancy
of your data, online and available at all times.
This helps increase our availability portion
of the CIA triad, and it helps us when we're designing
a high availability system.
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