How to format a disk or partition in Linux

Formatting a disk or partition in Linux replaces the filesystem metadata on the selected target so the device can be mounted as a fresh volume. The same action also makes the previous filesystem difficult to recover, so the safest starting point is a confirmed device path and a clear reason to erase it.

Linux exposes storage as block devices such as /dev/vdb and /dev/vdb1. lsblk shows the disk, partition, existing filesystem type, label, and mount point; wipefs shows the signatures that will be replaced; mkfs.ext4 writes the new ext4 filesystem; and blkid reads the label, type, and UUID after the format finishes.

This command flow formats one confirmed target as ext4 and assigns a filesystem label. Do not run the format command against the root filesystem, a boot partition, or a volume still serving applications. If the target cannot be unmounted cleanly, continue from maintenance media or another host before writing the new filesystem.

1. List the available block devices to identify the exact disk or partition that should be formatted.

   $ lsblk -o NAME,SIZE,TYPE,FSTYPE,LABEL,MOUNTPOINTS
   NAME          SIZE TYPE FSTYPE LABEL MOUNTPOINTS
   nvme0n1       100G disk
   |-nvme0n1p1   512M part vfat         /boot/efi
   `-nvme0n1p2  99.5G part ext4         /
   vdb           128M disk
   `-vdb1        127M part vfat   USB   /mnt/usb

   Use a partition path such as /dev/vdb1 when only one volume should be reformatted. Use a whole-disk path such as /dev/vdb only when the filesystem should live directly on the disk without partitions.

2. If the target from the previous step is mounted, unmount it before writing the new filesystem.

   $ sudo umount /dev/vdb1

   No output usually means the unmount completed cleanly.

   Related: How to unmount a disk in Linux

3. Inspect any existing signatures on the target before overwriting them.

   $ sudo wipefs --output DEVICE,OFFSET,TYPE,UUID,LABEL /dev/vdb1
   DEVICE OFFSET TYPE UUID      LABEL
   vdb1   0x36   vfat 2024-AFF0 USB
   vdb1   0x0    vfat 2024-AFF0 USB
   vdb1   0x1fe  vfat 2024-AFF0 USB

   If wipefs returns no data rows, the target does not currently expose a filesystem or partition-table signature that wipefs can identify.

4. Create the new ext4 filesystem and assign a label while writing the metadata.

   $ sudo mkfs.ext4 -L data /dev/vdb1
   mke2fs 1.47.2 (1-Jan-2025)
   Creating filesystem with 32512 4k blocks and 32512 inodes
   
   Allocating group tables: done
   Writing inode tables: done
   Creating journal (1024 blocks): done
   Writing superblocks and filesystem accounting information: done

   This step overwrites the previous filesystem metadata on the selected target. Replace data with the label required for that filesystem, and use a different filesystem-specific mkfs helper only when another filesystem type is intentionally required on the same confirmed device path.

5. Read the new filesystem metadata directly from the device to confirm that the format completed.

   $ sudo blkid /dev/vdb1
   /dev/vdb1: LABEL="data" UUID="e900bee5-aaf1-4632-97f1-faf41c4af558" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="30cd63c9-01"

   The TYPE=“ext4” and LABEL=“data” fields confirm the new filesystem. The UUID value is the stable identifier normally used later in /etc/fstab for persistent mounts.