Storage and file systems

Mounting filesystems: the mount command, persistent mounts in /etc/fstab, UUIDs and options.

A loop device shows a regular file to the system as a disk: you can partition, format and mount it.

Where the space and inodes went — df, du, finding large files, pitfalls.

LVM: physical volumes, volume groups and logical volumes (PV → VG → LV), extending and snapshots.

Filesystems: creating one with mkfs, labels and UUIDs, fsck checks, choosing between ext4 and xfs.

Network directories over NFS — exporting on the server, mounting on the client, permissions.

Software RAID on Linux — creating an array, checking status, replacing a disk.

Limiting space and file counts per user/group — enabling, configuring, reports.

A tree of disks, partitions, and logical volumes — size, filesystem, mountpoint.

fdisk and parted write a partition table (GPT or MBR) and partitions to a disk; parted -s runs without prompts.

The mkfs command creates an empty ext4 or xfs filesystem on a partition; the old data on it becomes unreachable.

The blkid command prints the UUID, label and type of the filesystem on a device — what goes into /etc/fstab.

Grow ext4/xfs after a volume grows — online growth, shrinking only on ext4 offline.

Creating and maintaining qcow2 disks — overlays, conversion, resizing.