This guide will walk you through on how to extend and increase space for the root filesystem on a alma linux. Cent OS, REHL Server/Desktop/VM

Method A – Expanding the current disk

Edit the VM and Add space to the Disk

install the cloud-utils-growpart package, as the growpart command in it makes it really easy to extend partitioned virtual disks.

sudo dnf install cloud-utils-growpart

Verify that the VM’s operating system recognizes the new increased size of the sda virtual disk, using lsblk or fdisk -l

sudo fdisk -l

Notes -
Note down the disk id and the partition number for Linux LVM - in this demo disk id is sda and lvm partition is sda 3

lets trigger a rescan of a block devices (Disks)

#elevate to root
sudo su 

#trigger a rescan, Make sure to match the disk ID you noted down before 
echo 1 > /sys/block/sda/device/rescan
exit

Now sudo fdisk -l shows the correct size of the disks

Use growpart to increase the partition size for the lvm

sudo growpart /dev/sda 3

Confirm the volume group name

sudo vgs

Extend the logical volume

sudo lvextend -l +100%FREE /dev/almalinux/root

Grow the file system size

sudo xfs_growfs /dev/almalinux/root

Notes -
You can use this same steps to add space to different partitions such as home, swap if needed

Method B -Adding a second Disk to the LVM and expanding space

Why add a second disk?
may be the the current Disk is locked due to a snapshot and you cant remove it, Only solution would be to add a second disk/

Check the current space available

sudo df -h 

Notes -
If you have 0% ~1MB left on the cs-root command auto-complete with tab and some of the later commands wont work, You should clear up atleast 4-10mb by clearing log files, temp files, etc

Mount an additional disk to the VM (Assuming this is a VM) and make sure the disk is visible on the OS level

sudo lvmdiskscan

OR

sudo fdisk -l

Confirm the volume group name

sudo vgs

Lets increase the space

First lets initialize the new disk we mounted

sudo mkfs.xfs /dev/sdb

Create the Physical volume

sudo pvcreate /dev/sdb

extend the volume group

sudo vgextend cs /dev/sdb

  Volume group "cs" successfully extended

Extend the logical volume

sudo lvextend -l +100%FREE /dev/cs/root

Grow the file system size

sudo xfs_growfs /dev/cs/root

Confirm the changes

sudo df -h

Just making easy for us!!

#Method A - Expanding the current disk 
#AlmaLinux
sudo dnf install cloud-utils-growpart

sudo lvmdiskscan
sudo fdisk -l                          #note down the disk ID and partition num


sudo su                                #elevate to root
echo 1 > /sys/block/sda/device/rescan  #trigger a rescan
exit                                   #exit root shell

sudo lvextend -l +100%FREE /dev/almalinux/root
sudo xfs_growfs /dev/almalinux/root
sudo df -h

#Method B - Adding a second Disk 
#CentOS

sudo lvmdiskscan
sudo fdisk -l
sudo vgs
sudo mkfs.xfs /dev/sdb
sudo pvcreate /dev/sdb
sudo vgextend cs /dev/sdb
sudo lvextend -l +100%FREE /dev/cs/root
sudo xfs_growfs /dev/cs/root
sudo df -h

#AlmaLinux

sudo lvmdiskscan
sudo fdisk -l
sudo vgs
sudo mkfs.xfs /dev/sdb
sudo pvcreate /dev/sdb
sudo vgextend almalinux /dev/sdb
sudo lvextend -l +100%FREE /dev/almalinux/root
sudo xfs_growfs /dev/almalinux/root
sudo df -h