Never power off or force reboot during a defrag. You can corrupt the filesystem. Let it finish or cancel properly.
False. It reorganizes existing files. Use recovery software for deleted files. defrag hdd
False. Weekly or monthly is plenty. Over-defragging wears out an HDD’s mechanical parts. Never power off or force reboot during a defrag
fsck.ext4 -fn /dev/sdX # reports fragmentation % defrag hdd