Filesystems, Mounting & fstab

Creating & Mounting Filesystems

FS	Notes
`ext4`	Long-standing Linux default, journaling
`xfs`	RHEL default, great for large files
`btrfs`	Snapshots, subvolumes
`vfat`/`exfat`	Cross-platform removable media

$ mkfs.ext4 /dev/sdb1            # create a filesystem
$ mkdir /data
$ mount /dev/sdb1 /data          # mount temporarily
$ umount /data                   # unmount

Persistent mounts - /etc/fstab

Each line: <device> <mountpoint> <fstype> <options> <dump> <pass>

UUID=1234-5678  /data  ext4  defaults  0 2

Prefer UUID (from blkid) over /dev/sdX - device names can change.
Test without rebooting: mount -a mounts everything in fstab.
pass = fsck order: 0 skip, 1 root, 2 others.

Exam trap: A bad /etc/fstab can leave a system unbootable. Always mount -a after editing to catch errors before rebooting.