Partitions, File Systems and Swap

Disks

Rescan/detect disk changes

echo 1>/sys/class/block/sdd/device/rescan

Partitioning

• linuxconfig.org | parted | fdisk | lsblk | sgdisk (GPT)
  • File systems: mkfs, mkswap
    • exFAT
      • package exfat-utils contains mkfs.exfat and exfatlabel
      • on Ubuntu/Debian package exfat-fuse
    • swap (not really a file system)
      • partition: mkswap [-L label] /dev/...
      • file: create sparse file (didn’t work for me 2023-02-16), see sparse files, or create dummy with dd if=/dev/zero of=/swap.img bs=1M count=4000 and then mkswap /swap.img
    • Partition types (parttype):
      • pt-mbr-partnames.h from util-linux package (lsblk) (doesn’t always match output of parted 🤦‍♂️)
      • Wikipedia: MBR partition types | GPT GUIDs
      • fdisk: chose l or L to print partition types (depending on partition table type MBR or GPT)

EFI

HowTo Create A GPT Disk With EFI System And exFAT Partitions Using Parted

File Systems

• FUSE
  • CVMFS: FUSE module which implements a HTTP read-only file system
• parallel and distributed
  • Lustre
  • GPFS

Labelling

# MS-DOS labels (didn't work as intended for FAT partition)
mlabel -i /dev/...  LABEL
# EXT
e2label /dev/... lblname
# NTFS
NTFS: ntfslabel device [label]
# FAT
(ex)fatlabel device [label]

Mount

findmnt
mount # verbose list of mount points

• Bind mount explained @StackExchange

• Overlay filesystem: ArchWiki

  mount -t overlay overlay -o lowerdir=/lower1:/lower2:/lower3,upperdir=/upper,workdir=/work /merged
  

  or in /etc/fstab

  overlay /merged overlay noauto,x-systemd.automount,lowerdir=/lower,upperdir=/upper,workdir=/work 0 0
  

Tools and Commands

• lsblk
• parted
  • only one to show free disk sectors: # parted /dev/xxx print free
  • unit only works with specifying a disk 🤦‍♂️
  • when letting parted align partitions for better performance (-a optimal) specify start/end in M
  • can be used in scripts like parted -s /dev/sda mklabel msdos mkpart primary ntfs 1M 100G mkpart primary ntfs 102400M 102912M mkpart primary 102912M
• fdisk
• sgdisk: for example helpful to wipe partition tables via sgdisk --zap-all /dev/name
• Allocate file of given size ^e79fc2

fallocate -l 10G file.img # best choice: actually reserved, but not written, so it's fast
truncate -s 10G gentoo_root.img # "sparse file", not properly allocated, fast
dd if=/dev/zero of=./gentoo_root.img bs=4k iflag=fullblock,count_bytes count=10G # slow, actually writes

• FSArchiver: save the contents of a file-system to a compressed archive file

References