- In this video,
I would like to talk about storage options.
So, it's all about the server, right?
(pen squeaking)
That is where Linux typically is seen.
So here you have your nice, big server
and you want to make sure that storage is proficient.
You can do one thing,
you can work with internal storage.
Also quite common,
is that you work with the SAN.
SAN is the Storage Area Network.
It's basically external storage.
SAN is just a collection of drives,
and this collection of drives
is going to be represented to Linux in one way or another.
A typical protocol to do so is the iSCSI protocol.
Now the result is that you will have
storage devices on your Linux system,
and you can use a command like lsblk
to figure out which storage devices are being used.
And basically, all storage devices are the same
but on the storage device itself,
you can do stuff.
So what are we going to do on the storage device?
Well, let's zoom in a little bit on the storage device
and let's assume that this is the storage device.
In order to use your storage device,
or your hard disc,
you don't normally use an entire hard disc in Linux.
Like in other operating systems,
you would create partitions.
And in Linux,
it's very common to work with multiple partitions,
where every file system is getting a partition
for the purpose that you are using it for.
For instance,
you will often see that there's a small boot partition.
That's a partition that is mounted
on the slash boot directory.
You might also see that there is a root partition.
That's a partition that is mounted on slash,
the root directory,
but it's also possible to work with this thing
that we call LVM,
the Logical Volume Manager.
And you know what?
Logical Volume Manager is taking one or more partitions,
and it's going to put these partitions
in another level of abstraction.
And that is the Logical Volume Level.
So in the logical volume environment,
you would create a volume group.
In this volume group,
really is the abstraction of all the storage that you have
and you put your partitions in there.
And the nice thing is,
that if you run out of storage in your volume group,
you can even add more partitions.
And based on that in the volume group,
you can create your logical volumes.
Logical volumes take their storage from the volume group.
You give them a specific size,
you run out of disc space,
then you can increase size of your logical volume.
And that is really useful,
because that allows you
to be really flexible at the storage level.
But these LVM logical volume groups
are a little more complex to set up.
In this course,
we are not going to really talk about LVM,
but I wanted to mention LVM anyway
because you will see it a lot,
even in a default server
of anything in the Red Hat family and on Ubuntu server,
you will get LVM by default.
But we do need to focus on these partitions.
And I will show you how this is going to be sda1,
and this is going to be sda2,
and these things are numbered.
And I will tell you all about it
in the next couple of videos.
So let's summarize with the slides
to list the block devices that you will encounter on Linux.
So there's /dev/sda.
/dev/sda's what you will see most commonly.
It's the name of the first SCSI hard disc device.
There's /dev/sdb.
/dev/sdb's the second SCSI hard disc device.
So, SD stands for SCSI disk,
A is the first, B is second, and so on.
Now we have /dev/vda.
You will see that on a KVM virtual machine.
KVM is Linux-based virtualization
and you will see it in particular environments.
And if it is used, vda is what you get.
And if you have a new, fancy, fast SSD device
you might see nvme0n1,
which is the first NVME hard disc.
And last, /dev/sr0,
which is an optical drive.
In the next video,
I'll show you how to create partitions on an NBR device.