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- In this video,

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I would like to talk
about storage options.

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So, it's all about the server, right?

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(pen squeaking)

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That is where Linux typically is seen.

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So here you have your nice, big server

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and you want to make sure
that storage is proficient.

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You can do one thing,

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you can work with internal storage.

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Also quite common,

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is that you work with the SAN.

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SAN is the Storage Area Network.

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It's basically external storage.

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SAN is just a collection of drives,

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and this collection of drives

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is going to be represented to
Linux in one way or another.

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A typical protocol to do
so is the iSCSI protocol.

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Now the result is that you will have

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storage devices on your Linux system,

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and you can use a command like lsblk

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to figure out which storage
devices are being used.

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And basically, all storage
devices are the same

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but on the storage device itself,

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you can do stuff.

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So what are we going to
do on the storage device?

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Well, let's zoom in a little
bit on the storage device

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and let's assume that this
is the storage device.

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In order to use your storage device,

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or your hard disc,

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you don't normally use an
entire hard disc in Linux.

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Like in other operating systems,

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you would create partitions.

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And in Linux,

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it's very common to work
with multiple partitions,

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where every file system
is getting a partition

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for the purpose that you are using it for.

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For instance,

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you will often see that
there's a small boot partition.

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That's a partition that is mounted

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on the slash boot directory.

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You might also see that
there is a root partition.

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That's a partition that
is mounted on slash,

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the root directory,

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but it's also possible
to work with this thing

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that we call LVM,

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the Logical Volume Manager.

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And you know what?

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Logical Volume Manager is
taking one or more partitions,

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and it's going to put these partitions

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in another level of abstraction.

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And that is the Logical Volume Level.

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So in the logical volume environment,

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you would create a volume group.

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In this volume group,

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really is the abstraction of
all the storage that you have

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and you put your partitions in there.

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And the nice thing is,

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that if you run out of
storage in your volume group,

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you can even add more partitions.

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And based on that in the volume group,

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you can create your logical volumes.

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Logical volumes take their
storage from the volume group.

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You give them a specific size,

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you run out of disc space,

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then you can increase size
of your logical volume.

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And that is really useful,

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because that allows you

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to be really flexible
at the storage level.

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But these LVM logical volume groups

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are a little more complex to set up.

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In this course,

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we are not going to really talk about LVM,

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but I wanted to mention LVM anyway

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because you will see it a lot,

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even in a default server

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of anything in the Red Hat
family and on Ubuntu server,

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you will get LVM by default.

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But we do need to focus
on these partitions.

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And I will show you how
this is going to be sda1,

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and this is going to be sda2,

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and these things are numbered.

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And I will tell you all about it

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in the next couple of videos.

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So let's summarize with the slides

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to list the block devices that
you will encounter on Linux.

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So there's /dev/sda.

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/dev/sda's what you
will see most commonly.

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It's the name of the first
SCSI hard disc device.

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There's /dev/sdb.

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/dev/sdb's the second
SCSI hard disc device.

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So, SD stands for SCSI disk,

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A is the first, B is second, and so on.

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Now we have /dev/vda.

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You will see that on
a KVM virtual machine.

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KVM is Linux-based virtualization

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and you will see it in
particular environments.

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And if it is used, vda is what you get.

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And if you have a new,
fancy, fast SSD device

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you might see nvme0n1,

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which is the first NVME hard disc.

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And last, /dev/sr0,

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which is an optical drive.

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In the next video,

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I'll show you how to create
partitions on an NBR device.