midka

I recently had to extend a normal disk partition. It wasn't fun. That's why I recommend using LVM, it's a lot easier to manage, extend, shrink and remove partitions on a single or multiple disks.

Common Terms

Physical Volumes (PVs) are your physical disks attached to a server. These can be different sizes. That's why LVM is so flexible.

Volume Groups (VGs) are groups of PVs. For example you could have vg00 which includes PVs a, b and c.

Logical Volumes (LVs) are smaller “partitions” of VGs. You can mount these at different mount points and are easily manageable.

Example

Your server configuration:

• Disk /dev/sda, 200GB
  • other partitions like boot
  • /dev/sda2, 199GB, PV
• Disk /dev/sdb, 4TB
  • /dev/sdb1, 4TB, PV
• Disk /dev/sdc, 150G
  • /dev/sdc1, 150G, PV

You can either split those into multiple VGs or combine them into one. I recommend combining them, because you can only assign a PV to single VG.

Currently your total allocatable storage for vg00 would be 4445GB. Now you can split that into one or more LVs and mount them to your system. I usually have different /, /var, /home and swap partitions.

Requirements

• A server
• An unused disk partition on the server
• LVM2 installed apt install lvm2 (on debian)

Creating a PV

sudo pvcreate <disk>

Example <disk> values:

• /dev/sdb
• /dev/sdb1

List PVs

sudo pvs

Creating a VG

sudo vgcreate <VG name> <PVs>

Example:

• sudo vgcreate vg00 /dev/sdb
• sudo vgcreate vg00 /dev/sda /dev/sdb /dev/sdc1

List VGs

sudo vgs

Creating a LV

sudo lvcreate -n <name> -L <size> <VG name>

Example:

• sudo lvcreate -n root -L 30G vg00
• sudo lvcreate -n home -L 50G vg00
• sudo lvcreate -n var -L 20G vg00

Formatting

You can choose any filesystem you want. I usually select ext4.

sudo mkfs.ext4 /dev/<VG name>/<LV name>

Example:

• sudo mkfs.ext4 /dev/vg00/root

Final Steps

Now you can mount them and store files. Remember to add them to /etc/fstab in order to automatically have them mounted.

sudo mount /dev/<VG name>/<LV name> /mnt

List LVs

sudo lvs

Extend a LV

sudo lvextend -L +2G /dev/<VG name>/<LV name> -r

The -r flag automatically resizes the filesystem. If it's not provided, you need to manually run the resize2fs <volume> command.

Example:

• sudo lvextend -L +2G /dev/vg00/root -r

Verify Changes

You can run df -h and it should show the new amount. If it still shows the old one, you can try running resize2fs /dev/<VG name>/<LV name> command.