Disk formatting on Fedora

Workflow: identify → confirm exact target and authorization → prefer non-destructive diagnosis → unmount/format/mount/fstab only when explicitly authorized → verify. Formatting, unmounting, fstab edits, and write tests are mutations; read-only review must stop before them.

Safety rules

• ALWAYS run lsblk -f first and confirm the exact device with the user before any destructive command.
• Reformatting erases ALL data. Warn explicitly and list what the user will lose. Ask for confirmation with the question tool when the target holds data.
• Never format a mounted filesystem or the system disk (check lsblk -f MOUNTPOINTS: /, /home, /boot are system).
• Double-check that sdb1 in the plan really is the user's data disk, not the installer stick or another disk with data.
• Use sudo -n only for a separately authorized operation; do not fall back to an interactive password prompt during autonomous review. Without authorization, stop at read-only inventory and record NOT-VERIFIED.
• After mkfs, run sync.

Why a disk can't be written to (check BEFORE reformatting)

Reformatting is the LAST resort, not the first fix. Most "can't create folder" cases have a non-destructive fix:

1. NTFS mounted read-only (mount | grep fuseblk shows (ro,...), journal shows ntfs-3g "Read-Only"): the volume has a "dirty" flag from Windows fast startup / hibernation / unclean shutdown. Fix WITHOUT data loss:
   • umount /dev/sdXN (or udisksctl unmount -b /dev/sdXN)
   • sudo ntfsfix /dev/sdXN (clears dirty flag, does not touch data)
   • Remount (replug or udisksctl mount -b /dev/sdXN) and verify with touch.
   • Still read-only? Windows-side fix: disable Fast Startup (powercfg /h off, or Control Panel → Power → Choose what power buttons do), run chkdsk X: /f.
2. vfat/FAT32 small files or old disk — filesystem fine but size limits (file > 4 GB impossible). Fix: exFAT or NTFS.
3. ext4 "read-only file system": sudo dmesg | tail for I/O errors; check SMART sudo smartctl -a /dev/sdX. A dying disk must not be reformatted — copy data first.
4. Permissions: dirs owned by root (sudo chown -R $USER:$USER <dir>).

Identify the disk

lsblk -f
# FSTYPE shows current fs, MOUNTPOINT shows if mounted
sudo blkid /dev/sdXN          # exact type/UUID

Unmount

umount /dev/sdXN               # if automounted under /run/media/...
udisksctl unmount -b /dev/sdXN # alternative

Format

Goal	Command	Notes
Fedora data disk	sudo mkfs.ext4 -F -L DATA /dev/sdXN	recommended for plain storage
Fedora system-ish	sudo mkfs.btrfs -f -L DATA /dev/sdXN	snapshot/compression (Fedora root is btrfs)
NTFS (Windows compat)	sudo mkfs.ntfs -f -L DATA /dev/sdXN	needs ntfs-3g package
exFAT (USB, >4GB files, cross-platform)	sudo mkfs.exfat -n DATA /dev/sdXN	needs exfatprogs
FAT32 (small USB)	sudo mkfs.fat -F 32 -n DATA /dev/sdXN	file size limit 4 GB

Permission note: mkfs.ext4 without sudo fails with "Permission denied" — always run with sudo.

Mount + ownership

sudo mkdir -p /home/$USER/DATA
sudo mount /dev/sdXN /home/$USER/DATA
sudo chown $USER:$USER /home/$USER/DATA

Do NOT pass uid=/gid= to mount for ext4 — ext4 rejects unknown options (Unknown parameter 'uid'). chown after mount instead. uid=1000 belongs to FAT/exFAT mounts only.

Auto-mount at boot (internal disks) — /etc/fstab

UUID=$(sudo blkid -s UUID -o value /dev/sdXN)
echo "UUID=$UUID /home/$USER/DATA ext4 defaults,noatime,nofail,x-systemd.device-timeout=10 0 2" | sudo tee -a /etc/fstab

• nofail + x-systemd.device-timeout=10: no boot hang if the disk is absent.
• Verify: grep -v "^#" /etc/fstab | tail, then sudo systemctl daemon-reload.

Verify write

# Authorized verification only; this creates and removes test data.
mkdir -p /home/$USER/DATA/test && touch /home/$USER/DATA/test/file.txt && echo OK && rm -rf /home/$USER/DATA/test
lsblk -f /dev/sdX

NTFS quirks after formatting

• ntfs-3g (FUSE) automounts via udisks2 under /run/media/<user>/<UUID>; if dirty flag set it mounts read-only — see "Why a disk can't be written to".
• ntfsfix -n is dry-run check; real fix is ntfsfix without -n.