Mar 23, 2016

0 Basic Guide To LVM

Logical Volume Management notes.

     1.       Tools needed :

sudo apt-get install lvm2 dmsetup mdadm reiserfsprogs xfsprogs

     2.       Layout explanation:

LVM consists of multiple drives, which make up a “Volume Group”.
Volume Group, can be divided into Logical Volumes.
Simple : You join many different disks in one and then you can cut,splice & glue it back.

     3.       LVM Setup

              # List disks in system.
sudo fdisk -l | grep GB

Disk /dev/sda: 107.4 GB, -system
Disk /dev/sdb: 107.4 GB, -newly added
Disk /dev/sdc: 107.4 GB, -newly added

# Find newly added disks without partition table.
sudo fdisk -l | grep doesn
Disk /dev/sdb doesn't contain a valid partition table
Disk /dev/sdc doesn't contain a valid partition table

# Partition drives.

sudo echo -e "n\np\n1\n\n\nt\n8e\nw" | fdisk /dev/sdb
sudo echo -e "n\np\n1\n\n\nt\n8e\nw" | fdisk /dev/sdc

     4.       Prepare partitioned drives for Volume Group.
sudo pvcreate /dev/sdb1 /dev/sdc1

                 # Display prepared partitions.
sudo pvdisplay

     5.       Create Volume Group

               # nas is used as name for Volume Group
sudo vgcreate nas /dev/sdb1 /dev/sdc1

     6.       Display newly created Volume Group.
sudo vgdisplay

     7.       Create logical volumes on the volume group nas.
sudo lvcreate --name share --size 20G nas
sudo lvcreate --name music --size 20G nas

     8.       Create filesystem on logical volumes.
sudo mkfs.ext4 /dev/nas/share -q
sudo mkfs.ext4 /dev/nas/music -q

     9.       Mount logical volumes.
               # Create mount point for logical volumes.
sudo mkdir /var/share /var/music

               # Mount logical volumes to created mount points.
sudo mount /dev/nas/share /var/share ;
sudo mount /dev/nas/music /var/music ;

     10.    Useful LVM commands.

               # Display logical volumes.

               # Remove logical volume.
{sudo umount /dev/nas/share ; sudo lvremove /dev/nas/share ;}

               # Extending a logical volume size.
sudo lvextend -r --size +20G /dev/nas/share

               # Reducing a logical volume
sudo lvreduce -r --size -10G /dev/nas/share


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