SD card or USB drive partitioning using fdisk
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- Introduction
- Insert the USB drive / SD card reader
- Unmount the partitions
- Partitioning with fdisk
- Build file system with mkfs tool
- Check the partitions
Introduction
In this tutorial we will learn how to create partitions for any hard disk drive (HDD), USB drive or micro SD card using the Linux tool called fdisk. We are going to build a file system in those partitions with another tool called mkfs.
Let’s create two partitions, the first one with fat32 filesystem and the second one with ext4 filesystem. This kind of partition combination generally used to create complete bootable operating system. The fat32 partition is used to store bootloader related files and the ext4 filesystem is used to store Linux files.
Insert the USB drive / SD card reader
When you insert an USB drive/USB card reader into the system USB port, the devices are created with names in the format sdX. Ex: sda, sdb etc. And the partitions are created in the format sdXY. Ex: sdb1, sdc1 etc. You can check the device name with the command lsblk after inserting the USB flash drive/ USB card reader.
lsblk
The output looks like following for the USB based device
sda 8:0 0 223.6G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
├─sda2 8:2 0 93.1G 0 part /
├─sda3 8:3 0 7.5G 0 part [SWAP]
└─sda4 8:4 0 122.5G 0 part
sdb 8:16 1 7.2G 0 disk
└─sdb1 8:17 1 7.2G 0 part /media/nayab/B414-8534
sr0 11:0 1 1024M 0 rom
For SD card inserted through SD card slot, the output looks like following. mmcblk0 is the SD card and mmcblk0p1 is the SD card partition.
sda 8:0 0 223.6G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
├─sda2 8:2 0 93.1G 0 part /
├─sda3 8:3 0 7.5G 0 part [SWAP]
└─sda4 8:4 0 122.5G 0 part
sr0 11:0 1 1024M 0 rom
mmcblk0 179:0 0 29G 0 disk
└─mmcblk0p1 179:1 0 29G 0 part /media/nayab/8D39-59F7
Usually sda will be your system internal hard drive. sdb or sdc will be your USB device (USB flash drive or USB card reader). mmcblk0 will be the SD card inserted through SD card slot. Cross check the device name with the lsblk command just after removing and again after inserting the device.
Unmount the partitions
Unmount the partition using the following command. This step is necessary to alter the partitions using fdisk.
sudo umount /dev/sdb1 # For USB based devices
or
sudo umount /dev/mmcblk0p1 # For Micro SD card
Partitioning with fdisk
Now run the fdisk command with the device path.
sudo fdisk /dev/mmcblk0 # Replace /dev/mmcblk0 with USB device name (ex: /dev/sdb or /dev/sdc) if you are using USB based device
Delete partitions
Type d multiple times until all partitions are deleted and type p to make sure the same.
Welcome to fdisk (util-linux 2.34).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): d
Selected partition 1
Partition 1 has been deleted.
Command (m for help): d
No partition is defined yet!
Command (m for help): p
Disk /dev/mmcblk0: 28.99 GiB, 31104958464 bytes, 60751872 sectors
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: dos
Disk identifier: 0x6c586e13
Create FAT32 partition
Now let’s create a primary partition of 1GB to store bootloader files
Command (m for help): p
Disk /dev/mmcblk0: 28.99 GiB, 31104958464 bytes, 60751872 sectors
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: dos
Disk identifier: 0x6c586e13
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-60751871, default 2048): 2048
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-60751871, default 60751871): +1G
Created a new partition 1 of type 'Linux' and of size 1 GiB.
Change the partition type to FAT32. Type t and then b.
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): b
Changed type of partition 'Linux' to 'W95 FAT32'.
Command (m for help): p
Disk /dev/mmcblk0: 28.99 GiB, 31104958464 bytes, 60751872 sectors
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: dos
Disk identifier: 0x6c586e13
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 2048 2099199 2097152 1G b W95 FAT32
Create Linux partition
Create one more partition with the remaining size. Type n and keep pressing Enter until the prompt repeates. Type t to change the partition type and write 83 to change it to Linux type.
Command (m for help): n
Partition type
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (2-4, default 2):
First sector (2099200-60751871, default 2099200):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2099200-60751871, default 60751871):
Created a new partition 2 of type 'Linux' and of size 28 GiB.
Command (m for help):
Command (m for help):
Command (m for help): t
Partition number (1,2, default 2): 2
Hex code (type L to list all codes): 83
Changed type of partition 'Linux' to 'Linux'.
Command (m for help): p
Disk /dev/mmcblk0: 28.99 GiB, 31104958464 bytes, 60751872 sectors
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: dos
Disk identifier: 0x6c586e13
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 2048 2099199 2097152 1G b W95 FAT32
/dev/mmcblk0p2 2099200 60751871 58652672 28G 83 Linux
Write changes to device
Type w to write partition changes to disks.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
Build file system with mkfs tool
Build fat32 filesystem for partition 1.
sudo mkfs.vfat /dev/mmcblk0p1 -n boot
Build Linux filesystem for partition 2.
sudo mkfs.ext4 /dev/mmcblk0p2 -L rootfs
Check the partitions
Remove the USB/Card reader device and then reinsert to verify the partitions using the lsblk command.
sda 8:0 0 223.6G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
├─sda2 8:2 0 93.1G 0 part /
├─sda3 8:3 0 7.5G 0 part [SWAP]
└─sda4 8:4 0 122.5G 0 part
sr0 11:0 1 1024M 0 rom
mmcblk0 179:0 0 29G 0 disk
├─mmcblk0p1 179:1 0 1G 0 part /media/nayab/boot
└─mmcblk0p2 179:2 0 28G 0 part /media/nayab/rootfs