Logical Volume Management (LVM)

https://www.howtoforge.com/linux_lvm

Creating LVMs

• Partition disks as Linux LVM with fdisk
• Prepare new partitions for LVM Example:

pvcreate /dev/sdb1 /dev/sdc1 /dev/sde1  # pvremove /dev/sdb1 /dev/sdc1 /dev/sde1 to revert
pvdisplay                               # to show Physycal volumenes

• Create a volume group example 'pilaf':

 vgcreate pilaf /dev/sdg1 /dev/sdf1  # vgremove pilaf to delete

• Check existing Volume Groups

vgdisplay
vgscan

• Create logical volumes in volume group

lvcreate --name pilaf_copy --size 4T pilaf
lvcreate --name pilaf_converter --size 4T pilaf

• Check existing logical volumes with:

lvdisplay / lvscan

• Rename logical volumes with

lvrename {volume_group} {old_name} {new_name}  | example: lvrename pilaf pilaf_copy pilaf_raw

• Enlarge/reduce Logical volume with:

lvextend -L4.5T /dev/pilaf/pilaf_raw
lvreduce -L4T /dev/pilaf/pilaf_raw

• Create the filesystems

mkfs.ext4 /dev/pilaf/pilaf_raw
mkfs.ext4 /dev/pilaf/pilaf_converter

• Add /etc/fstab entries

/dev/pilaf/pilaf_raw          /Pilaf               ext4        rw,noatime    0 0
/dev/pilaf/pilaf_converter    /PilafConverter      ext4        rw,noatime    0 0

Resize LVM Logical Volumes & Filesystems

Enlarge

• Unmount the Logical Volume

/umount /PilafConverter

• Extend the Logical Volume

lvextend -L 4.5T /dev/pilaf/pilaf_converter

• Extend the filesystem

e2fsck -f /dev/pilaf/pilaf_converter
resize2fs /dev/pilaf/pilaf_converter

• Mount again

mount /dev/pilaf/pilaf_converter /PilafConverter

Shrink

• Unmount the Logical Volume

/umount /PilafConverter

• Shrink (Requires a number of blocks)

e2fsck -f /dev/pilaf/pilaf_converter  # to figure out the blocks we want to keep
resize2fs /dev/pilaf/pilaf_converter 104857600
lvreduce -L40G /dev/pilaf/pilaf_converter

• Mount again

mount /dev/pilaf/pilaf_converter /PilafConverter

Add/Remove Hard Drives

Add

• Format the new HD with fdisk (Linux LVM)

fdisk /dev/sdX (n (new)--> p (primary)--> 1 (default sdX1)--> t --> Linux LVM (8e|30) --> w)

• Prepare

pvcreate /dev/sdX1

• Extend Volume Group

vgextend fileserver /dev/sdX1

• Check

vgdisplay

Remove

• Move data to some other disk

pvmove /dev/sdb1 /dev/sdf1

• Remove disk from Volume Group

vgreduce fileserver /dev/sdb1
vgdisplay

• Remove Phisical Volume

pvremove /dev/sdb1
pvdisplay