Partitioning: Part 1 (Demo)
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>> Hello, Cybrarians and welcome back to
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the Linux plus course here at Cybrary.
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I'm your instructor Rob Goelz, and in today's lesson,
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we'll be covering the first part of
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our two parter on partitioning.
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Upon completion of today's lesson,
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you are going to understand MBR and GPT partitioning.
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We're also going to cover fdisk and gdisk commands
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to create partitions.
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What is the MBR? Well, MBR partitioning;
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the master boot record partitioning,
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was designed to hold
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four primary partition table entries.
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Please, keep this in mind and remember
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these four primary partitions,
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this will come up in other exams
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>> that you might get into,
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>> and it probably will come up on the Linux plus exam.
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This limitation was bypassed down
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the road by allowing extended partitions,
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but you can still only have four primary partitions.
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Another limitation, a disk using MBR partitions
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is only allowed to be 2.2 terabytes in size,
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and that's due to a 32-bit
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>> memory addressing limitation.
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>> Now, MBR partitions are closely
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related with BIOS and legacy boot,
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so when you think BIOS and legacy boot,
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you're going to think MBR.
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Now GPT; the GUID partition table was created
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to overcome some of
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these limitations that we found in the BIOS.
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A GPT partition is one partition
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that extends across an entire disk and
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the portions that are
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partitioned are logical block addresses, LBAs.
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GPT uses 64-bit LBA addressing,
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which means that this can go up to
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eight zettabytes in size.
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I don't know about any of you,
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but I've never seen a zettabyte in my entire life,
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so I think we're probably pretty good for the future,
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future proofing there with eight zettabytes.
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GPT partitions are closely related with UEFI, EFI boot.
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The EFI system partition we talked about in
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Module 1 is actually a GPT partition.
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Let's go ahead and get on to
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some demo time and take a look at this.
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We're over here in our CentOS environment again today.
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The first thing we'll look at is the fdisk command.
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When we think about fdisk,
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think about MBR and legacy and BIOS.
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What we can do is first take a
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>> look at our disk devices,
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>> and we can do this by doing an ls on
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the device, the dev partition.
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We're just going to look for things that start with
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sd, so sd star.
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What we can see is dev sda and then sda 1,
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2, 3, 4, 5 and dev sdb.
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Well, this is a disk,
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dev sda and the partitions are 1,
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2, 3, 4, 5.
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We can see that dev sdb is
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just a disk with no partitions.
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That's what we're going to use.
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What we're going to do to run the fdisk command is
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we need to elevate our privileges first of all.
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We're going to do dev, let's see,
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sudo fdisk and let's
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go ahead and print out some information.
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Let's list with the l option.
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Let's list some information on the sdb partition.
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We're going to type in the password here to elevate
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the privileges and we can
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see the information about this disk.
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This disk, dev sdb is eight gigs in size.
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Now, if we want to add
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a partition to this disk using fdisk,
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we can just take off the l and what will happen
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is we'll get into an interactive shell,
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an fdisk command shell where we can do things.
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The first thing that we're going to want to do
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is type m right here for help.
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What we can see is that in order to
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>> add a new partition,
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>> we actually have to use the character n,
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n for new partition.
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We're going to hit "N" and that's going
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to prompt us for what we want the
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>> partition number to be.
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>> I don't particularly care,
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so we'll accept the default as one and we'll also
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accept the default for the first available sector,
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there's 2048 and just hit "Enter."
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Now the last sector we can actually
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>> just specify a size.
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>> Instead of having to do the math
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and determine what sector it would be,
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we can just say, "Hey, we want the scene
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to be one gig in size."
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We can use plus size number and then the type.
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We're going to create a plus 1
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gig partition and we hit "Enter."
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We're off to the races, we created
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a new partition of type
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Linux file system and size one gig.
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Now if we hit P, because remember right up
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here it says P for print the partition table,
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we can print the partition table.
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That's what we need to do.
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Now if we wanted to commit
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this change and create the partition,
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we could type the W command to write this out and exit.
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But because this isn't the only
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command we're going to be playing with today,
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we're just going to hit, "Q" for quit
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and now nothing is done.
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No changes have been committed.
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We haven't created a partition and in fact,
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we can do an ls on dev sdbs,
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dev sd star again.
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We can see that we have
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dev sda with all these partitions,
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but dev sdb has been left alone.
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There's no sdb1 and we're good to go.
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Let's go ahead and clear our screen.
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I'm going to hit, "Control L" to do that.
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Now what we'll do is move over.
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We'll look at the gdisk command.
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Gdisk works pretty similar to fdisk.
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Just keep in mind when you see gdisk,
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think about UEFI and large drives
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that are bigger than 2.2 terabytes.
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Remember, MBR partitioning using
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fdisk only allows you to go up to
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2.2 terabytes in size on disk,
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but you can go up to eight zettabytes
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using GPT partitioning.
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Just like we saw with fdisk,
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we can do the same thing with gdisk to
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display the information about our disk.
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We can do sudo gdisk dash l,
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and then do that on dev sdb.
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We can see all sorts of good
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>> information about our disk.
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>> But pretty much the only thing we
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really care about here is
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that we have an eight gig disk, size eight gig.
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What we can do in order to create
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a partition is go into this
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using sudo gdisk and get
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into an interactive prompt just like we saw before.
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Now, by comparison to
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fdisk with gdisk in order to get help,
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we need to type the question mark instead of
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m. But just like with fdisk,
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in gdisk, we can see that in
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order to add a new partition,
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we hit the n character on our keyboard.
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Now, we're going to get prompted and it's going
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to look probably pretty similar.
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We're going to accept the partition number default.
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We'll also accept the first sector here.
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Then to determine the last sector,
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why should I just give it a size?
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We're going to say one gig again and then hit "Enter."
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Now a little different wrinkle here.
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It'll actually say that we're going to get this
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as the Linux file system but if we wanted
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to change the type of partition, we could do that.
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We can hit, "L" and hit
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Enter and we'll see all of the different codes.
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We can hit, "Enter" and see more codes.
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But for our purposes, we just want this to be
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a Linux file system 8300 so we can just hit,
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"Enter" to accept 8300.
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Now if we wanted to see
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the contents of this that has been printed out,
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we should be able to choose P
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>> and we see the same thing.
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>> We see that we have
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a single partition that
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is one gig in size and it has code 8300,
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which is the Linux file system type.
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For our purposes, let's go ahead and write
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this out so we can see this being changed.
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We're going to write GPT data.
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This will overwrite existing partitions.
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That's okay because we're working in dev sdb.
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It's a disk that I assigned to
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this virtual machine specifically
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for this exercise so no harm, no foul.
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I'm going to hit, "Y" and hit, "Enter"
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and now we'll see that that's been created.
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Now if we go ls dev sdb,
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or ls dev sd star,
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we can see not only do we have
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sda with all of its partitions,
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but we have sdb in a single partition.
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We've reached the end of the lesson today.
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In today's lesson, we covered
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the MBR and GPT partition types.
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We talked about the fdisk and gdisk commands.
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Thanks so much for being here and I
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hope to see you in the next lesson.
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