Master Linux Storage Management: Devices, Mounting, Partitioning & Quotas

1. Device Inspection

Use the following commands to inspect devices: fdisk -l – view disk partition information lsblk – display block device usage blkid – show device IDs and management methods df – list currently mounted devices cat /proc/partitions – view system‑recognized devices

2. Device Mounting

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

mount -o <em>options</em> <em>device</em> <em>mount_point</em>
umount <em>device|mount_point</em>    # unmount
mount                         # view mount info
mount -o rw /dev/vda1 /dir    # mount read‑write
mount -o remount,ro /dir      # remount read‑only

Note: The above are temporary mounts. For permanent mounts edit /etc/fstab:

(1) vim /etc/fstab    # edit fstab file
Device   MountPoint   FS_Type   Options   Dump   Pass
/dev/sr0 /westos      iso9660   defaults   0      0
mount -a               # reload fstab

3. Finding Files on Devices

Common find examples: find /etc/ -name passwd – locate files named passwd under /etc recursively find /etc/ -maxdepth 1 -name passwd – search only the top‑level /etc directory find /etc/ -maxdepth 2 -mindepth 2 -name passwd – search exactly one level below

/etc

find /mnt -user westos

– files owned by user westos find /mnt -user westos -o -user lee – files owned by westos OR lee find /mnt -user westos -a -group lee – files owned by westos AND belonging to group lee find /mnt -type d – list directories find /mnt -perm 111 – files with exact permission 111 find /mnt -perm -111 – files where all three permission bits include execute find /mnt -perm /111 -type f -exec chmod ugo-x {} \\; – remove execute bits from matching regular files

4. Disk Partitioning

Standard Partitioning (MBR)

Primary partition – recorded in the partition table and directly usable

Extended partition – container for logical partitions, not directly usable

Logical partition – resides within an extended partition

Partition tools: fdisk /dev/vdb – interactive partitioning parted – supports both interactive and non‑interactive modes

Important:

After using fdisk, run the partition‑table sync command before checking with fdisk -l.

After creating partitions, format them before mounting, e.g. mkfs.xfs -K /dev/yourdisk -f (‑K speeds up formatting by not discarding empty blocks).

Swap Partition

Swap provides a disk‑based memory buffer when RAM is exhausted. Commands:

swapon -s                     # view swap info
# Create swap:
# 1. Create a partition of type Linux‑swap
# 2. mkswap /dev/yourdisk       # format as swap
# 3. swapon /dev/yourdisk -p 0  # enable with priority
# To make it permanent, add to /etc/fstab:
/dev/yourdisk swap swap defaults,pri=1 0 0
swapon -a                     # activate all swaps in fstab
# To remove swap:
# Edit /etc/fstab to delete the line, then:
swapoff /dev/yourdisk

Device Deletion

Delete partitions using various methods: dd if=/dev/zero of=/dev/yourdisk bs=1M count=1 – wipe all partitions at once fdisk /dev/yourdisk – interactive delete (choose d then partition number) parted /dev/yourdisk rm <em>partition_number</em> – non‑interactive delete

Note: Unmount devices before modifying partitions.

5. Disk Quotas

Quotas limit the amount of storage a user can consume.

# Steps:
1. Create a partition and format it.
2. Enable quota on mount:
   mount /dev/yourdisk /pub -o usrquota
   quotaon -uv /dev/yourdisk
   edquota -u lee   # edit user lee's quota
3. Make quota permanent by adding to /etc/fstab:
   /dev/sda1 /pub xfs defaults,usrquota 0 0
4. Disable quota:
   quotaoff -uv /dev/yourdisk
   # remove usrquota from /etc/fstab

Important: Only modify the hard limit; other fields are system‑generated.

# Test quota:
su - lee
cd /target_dir
dd if=/dev/zero of=/target_dir/file bs=1M count=22   # should fail after 20 MiB