Master Linux Storage: Device Discovery, Mounting, Partitioning & Quotas

Linux Storage Management Basics

Storage management is a fundamental topic in Linux, covering device identification, viewing, mounting, file location, and disk partitioning.

1. Device Viewing

Use commands to inspect devices:

fdisk -l   # view partition table

lsblk     # show block devices

blkid     # display device IDs

df        # list mounted filesystems

cat /proc/partitions   # view system-recognized devices

2. Device Mounting

Only devices with a system ID can be used. Basic mount commands:

mount -o [options] device mount_point

umount device|mount_point   # unmount

Example:

mount -o rw /dev/vda1 /dir

mount -o remount,ro /dir   # remount read‑only

When a device is busy, use:

fuser -kvm device|mount_point   # kill processes, show details

Temporary mounts are performed with the above commands; permanent mounts are defined in /etc/fstab: vim /etc/fstab # edit fstab After editing, apply with: mount -a # reload fstab Incorrect fstab entries can prevent boot; comment out errors and reboot.

3. Finding Files on Devices

Common find examples: find /etc/ -name passwd Search only the /etc directory (no subdirectories): find /etc/ -maxdepth 1 -name passwd Search one level deep: find /etc/ -maxdepth 2 -name passwd Search only subdirectories: find /etc/ -maxdepth 2 -mindepth 2 -name passwd Search files owned by a specific user: find /mnt -user westos Combine conditions with OR or AND:

find /mnt -user westos -o -user lee   # OR

find /mnt -user westos -a -group lee   # AND

Search by type, permission, and execute actions:

find /mnt -type d                     # directories

find /mnt -perm 111                   # exact permission 111

find /mnt -perm -111                  # at least these bits

find /mnt -perm /111                  # any of the bits

find /mnt -perm /111 -type f -exec chmod ugo-x {} \;

4. Disk Partitioning

Standard Partitions

MBR partition scheme includes primary, extended, and logical partitions.

Primary partitions are directly usable; extended partitions act as containers for logical partitions.

Partitioning tools:

fdisk /dev/vdb   # interactive partitioning

parted           # non‑interactive or interactive mode

After creating partitions with fdisk, synchronize the partition table before listing: partprobe # or re‑run fdisk -l Format new partitions before mounting, e.g. XFS:

mkfs.xfs -K /dev/<disk_name>   # -K speeds up formatting

Swap Partition

Swap provides a memory buffer when RAM is exhausted. swapon -s # view swap Create swap:

mkswap /dev/<disk_name>       # format as swap

swapon /dev/<disk_name> -p 0  # enable with priority

Make swap permanent by adding to /etc/fstab:

vim /etc/fstab   # add: /dev/<disk_name> swap swap defaults,pri=1 0 0

swapon -a        # apply

Remove swap by editing /etc/fstab and running swapoff.

Device Deletion

Delete partitions using:

dd if=/dev/zero of=/dev/<disk_name> bs=1M count=1   # wipe partition table

fdisk /dev/<disk_name>   # interactive delete (d)

parted                  # non‑interactive delete with rm

5. Disk Quotas

Quotas limit the amount of space a user can consume.

mount /dev/<disk_name> /pub/ -o usrquota   # enable quota on mount

quotaon -uv /dev/<disk_name>               # activate

edquota -u lee                            # edit user quota

Typical edquota output shows soft and hard limits for blocks and inodes.

Make quotas permanent by adding usrquota to /etc/fstab:

vim /etc/fstab   # /dev/sda1 /pub xfs defaults,usrquota 0 0

Disable with quotaoff -uv /dev/<disk_name> and remove the option from /etc/fstab.

Test quota by attempting to write beyond the limit, e.g. using dd if=/dev/zero of=/path/file bs=1M count=22, which should fail after reaching the soft limit.