Add new partitions, logical volumes, and swap non-destructively

5. Configure Local Storage

📘Red Hat Certified System Administrator (RHCSA – EX200)

In IT systems, sometimes you need to increase storage or add space without losing your existing data. This is called non-destructive storage management. It is critical for servers, virtual machines, or network devices that must remain online while storage changes.

This topic has three main areas:

Adding partitions
Adding logical volumes (LVs)
Adding swap space

1. Adding New Partitions Non-Destructively

A partition is a section of a hard disk (or SSD) that the OS treats as separate storage. Non-destructive partitioning means creating or resizing partitions without deleting existing data.

Key points for the exam:

Identify free space:
Before adding a partition, check available disk space using: lsblk
fdisk -l This shows disks, partitions, and free/unallocated space.
Create a new partition:
- Use fdisk or parted.
  Example with fdisk: sudo fdisk /dev/sdb Then:
  - n → create new partition
  - p → primary (or e for extended)
  - Assign size (e.g., +10G)
  - w → write changes
Format the new partition: sudo mkfs.ext4 /dev/sdb1
Mount the partition: sudo mkdir /data
sudo mount /dev/sdb1 /data Add it to /etc/fstab to mount at boot: /dev/sdb1 /data ext4 defaults 0 0

Exam tip: You do not destroy existing partitions or files on other parts of the disk. Only new partitions are created in free space.

2. Adding Logical Volumes (LVs) Non-Destructively

A Logical Volume (LV) is part of a Volume Group (VG), which itself is made from Physical Volumes (PVs). LVM (Logical Volume Manager) allows you to:

Resize storage dynamically
Combine multiple disks
Add new storage without touching existing data

Steps to add new LV:

Check existing volume groups: vgdisplay
Check free space in VG: vgs
Create a new logical volume: lvcreate -L 10G -n lv_data vg1
- -L 10G → size
- -n lv_data → LV name
- vg1 → target VG
Format the LV: mkfs.ext4 /dev/vg1/lv_data
Mount the LV: mkdir /mnt/data
mount /dev/vg1/lv_data /mnt/data
Add to /etc/fstab for persistence: /dev/vg1/lv_data /mnt/data ext4 defaults 0 0

Non-destructive benefit:
Existing LVs and files stay intact. You just allocate new space from the available free PVs.

3. Adding Swap Non-Destructively

Swap space is virtual memory used when RAM is full. You can add swap without affecting existing data by:

Option A: Using a Swap File

Create a swap file: sudo fallocate -l 2G /swapfile Or: sudo dd if=/dev/zero of=/swapfile bs=1M count=2048
Set permissions: sudo chmod 600 /swapfile
Make it swap: sudo mkswap /swapfile
Enable swap: sudo swapon /swapfile
Add to /etc/fstab to make permanent: /swapfile swap swap defaults 0 0

Option B: Using a Swap Partition

Create a new partition (as in step 1)
Format as swap: mkswap /dev/sdb2
Activate it: swapon /dev/sdb2
Add to /etc/fstab: /dev/sdb2 swap swap defaults 0 0

Key exam point: Swap can be added without touching existing partitions or files, making it safe for running systems.

Best Practices for Non-Destructive Storage Changes

Always check disk and LV free space before adding new storage.
Backup important data – even though it’s non-destructive, mistakes can happen.
Update /etc/fstab for persistent mounts.
Use descriptive names for partitions, LVs, and mount points to avoid confusion.
Verify with df -h or lsblk after changes.

Exam Summary Checklist

Task	Command / Notes
List disks & partitions	`lsblk`, `fdisk -l`
Create new partition	`fdisk /dev/sdx` → `n` → size → `w`
Format partition	`mkfs.ext4 /dev/sdx1`
Mount partition	`mount /dev/sdx1 /mountpoint`
Create LV	`lvcreate -L 10G -n lvname vgname`
Format LV	`mkfs.ext4 /dev/vgname/lvname`
Mount LV	`mount /dev/vgname/lvname /mountpoint`
Create swap file	`fallocate -l 2G /swapfile`
Enable swap	`swapon /swapfile`
Persistent mount/swap	Edit `/etc/fstab`

✅ Tip for non-IT students: Think of partition, LV, or swap as separate “storage containers” on your server. Non-destructive means you can add a new container without spilling or deleting anything in the old containers.