Exercise: Partition a new disk

servera has an empty 5 GiB disk, /dev/sdb. Look at the disks, give it a GPT partition table, and carve out three partitions for the rest of the chapter: a data partition, an archive partition, and a swap partition.

Partition a new disk

Identify the system disk and the spare disk.
Create a GPT table and three partitions with parted.
Check the result with lsblk and parted.

Start the exercise

On workstation, start the exercise. It clears the spare disk /dev/sdb of servera (5 GiB).

[student@workstation ~]$ lab start sa-partitions

Later tasks assume that you are logged in to the server they name: ssh student@servera from workstation, then sudo -i for a root shell.

Which disk is which?

On servera as root (sudo -i), list the block devices with their file systems. Which disk is the system disk, and which one is empty?

[student@workstation ~]$ ssh student@servera
[student@servera ~]$ sudo -i
[root@servera ~]# lsblk -f
NAME   FSTYPE FSVER LABEL  UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda
├─sda1 vfat   FAT32 UEFI   76E8-0192                              90.8M     8% /boot/efi
└─sda2 ext4   1.0   rootfs 4bbdcf8d-863d-4050-957c-c815ca3838b8   17.5G     9% /
sdb

sda holds / and /boot/efi: it is the system disk. sdb has no partitions, no file system and no mount point: it is free for use.

Read the partition table

Ask parted for the table of /dev/sdb. What does the error mean?

[root@servera ~]# parted -s /dev/sdb print
Error: /dev/sdb: unrecognised disk label
Model: QEMU QEMU HARDDISK (scsi)
Disk /dev/sdb: 5369MB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags:

"Unrecognised disk label" means there is no partition table at all. The size (about 5.4 GB) matches the 5 GiB disk.

Create the table and three partitions

Create a GPT label, then partitions named data (1 GiB, xfs), logs (1 GiB, ext4) and swap (512 MiB, linux-swap), the first starting at 1 MiB and each following directly after the previous one.

[root@servera ~]# parted -s /dev/sdb mklabel gpt
[root@servera ~]# parted -s /dev/sdb mkpart data xfs 1MiB 1025MiB
[root@servera ~]# parted -s /dev/sdb mkpart logs ext4 1025MiB 2049MiB
[root@servera ~]# parted -s /dev/sdb mkpart swap linux-swap 2049MiB 2561MiB

Check the result

Wait for the device files, then show the partitions with lsblk and with parted, and the sizes in MiB including the free space.

[root@servera ~]# udevadm settle; lsblk /dev/sdb
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sdb      8:16   0    5G  0 disk
├─sdb1   8:17   0    1G  0 part
├─sdb2   8:18   0    1G  0 part
└─sdb3   8:19   0  512M  0 part
[root@servera ~]# parted -s /dev/sdb unit MiB print free | tail -7
Number  Start    End      Size     File system     Name  Flags
        0.02MiB  1.00MiB  0.98MiB  Free Space
 1      1.00MiB  1025MiB  1024MiB  xfs             data
 2      1025MiB  2049MiB  1024MiB  ext4            logs
 3      2049MiB  2561MiB  512MiB   linux-swap(v1)  swap  swap
        2561MiB  5120MiB  2559MiB  Free Space

About 2.5 GiB remain free for later. (The xfs/ext4 words in the table are hints; no file system exists yet. That is the next lesson.)

Look at it from the other side

Print the table with fdisk -l /dev/sdb and compare with parted. Which type of table does it report?

[root@servera ~]# fdisk -l /dev/sdb
Disk /dev/sdb: 5 GiB, 5368709120 bytes, 10485760 sectors
Disk model: QEMU HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 47F1B88E-3D30-4B06-9E55-37BF315E4107

Device       Start     End Sectors  Size Type
/dev/sdb1     2048 2099199 2097152    1G Linux filesystem
/dev/sdb2  2099200 4196351 2097152    1G Linux filesystem
/dev/sdb3  4196352 5244927 1048576  512M Linux swap

Disklabel type: gpt: fdisk and parted read the same table. Sector 2048 is exactly 1 MiB, the aligned start.

Grade and finish

Check your work with lab grade sa-partitions, then put the exercise away with lab finish sa-partitions.