This is a recurrent operation I’m doing regularly these time : extending a Linux partition by adding new virtual disk I’ve attached to a growing VM. Nothing fantastic to expect in this post. Its purpose is to keep on my hand the solution I’ve used to stop searching google and getting a different one every time ;).

This tuto is applicable for centos 7. The content will be updated when I’ll have to perform different operations.

Install LVM

yum install lvm2

With default tools

• PV – Physical Volume = raw disk
• VG – Volume Group = group of PV
• LV – Logical Volume, partition of VG we can mount

Initialize a PV:

1. use fdisk to create a partition type 8e (LVM)
2. create the associated PV with pvcreate /dev/sdxy

Create a VG

1. vgcreate name_of_the_group /dev/sdxy /dev/sd..
2. verify : vgdisplay

Create the LV

1. lvcreate -n lv_name –size XXG vg_name or lvcreate -l 100%FREE vg_name
2. verify : lvdisplay
3. format: mkfs.ext4 /dev/vg_name/lv_name
4. add in fstab

/dev/vg_name/lv_name /mount_point ext4 defaults 0 0

When it is expected to spread data across different VG in a Raid0 type LV

lvcreate --type raid0 -l 100%FREE --stripes 3 --stripesize 4 -n ln_name vg_name

stripes 3 option is indicating to spread across 3 PV of the VG stripesize 4 is for block of 4K

BTRFS can be used for compression:

Install on ubuntu : apt install btrfs-progs
Create fs: mkfs.btrfs /dev/vg_name/lv_name
Add in /etc/fstab
/dev/vg_name/lv_name /mount_point btrfs defaults,compress 0 1

Install some tool for helping

# yum install system-storage-manager

Display the running configuration

# ssm list

Create a volume ready for being extended from scratch

Here is an example for a LVM Pool initialized with 1 drive

# ssm create -s 50G -n disk0 --fstype xfs -p pool-name /dev/sdX /mnt/point

we can add drives to the pool :

# ssm add -p pool-name /dev/sdX

Add the entry into the fstab

/dev/dm-0         /mnt/point            xfs     defaults     0 0

References

• http://xmodulo.com/manage-lvm-volumes-centos-rhel-7-system-storage-manager.html