1. Logical Volume Manager

• • An Introduction

2. Logical Volume Manager What is?

LVM(Logical Volume Manager) allows to manage disks in a different way: creates one or more virtual disks with virtual partitions, from physical partitions

No limited by physical disk

3. Logical Volume Manager What is?

LVM(Logical Volume Manager) allows to manage disks in a different way: creates one or more virtual disks with virtual partitions, from physical partitions

No limited by physical disk

4. Logical Volume Manager Concepts

Physical Volume(PV) : physical partition from real disk

Volume Group(VG) : like a virtual disk

Logical Volume(LV) : a partition in a Volume Group

Physical Extent(PE) : like a 'cluster' in PV

Logical Extent(LE) : like a 'cluster' in LV

5. Logical Volume Manager Concepts

Create one or more VG from one or more PV, and then create LVs in each VG

VG /dev/sda1 /dev/vg/lv1 /dev/sda2 /dev/vg/lv2 /dev/vg/lv3 6. Logical Volume Manager PVs

pvcreate: creates a PV

pvremove: removes a PV

pvdisplay: shows information about a PV

pvscan: scan all PVs in the system

pvck: check a PV for errors

(1) Create one or more partitions with fdisk, with type LVM (2)pvcreate /dev/ 7. Logical Volume Manager VGs

vgcreate: creates a VG

vgremove: removes a VG

vgextend: extend a VG with more PVs

vgreduce: drops PVs from a VG

vgdisplay: shows info about VG

vgscan: scan for all VGs in system

vgchange: change VG properties

vgck, vgexport, vgmerge, vgsplit, vgrename

8. Logical Volume Manager VGs (1) Create one or more partitions with fdisk, with type LVM (2)pvcreate /dev/sda1 (3)pvcreate /dev/hdb2 (4)pvcreate /dev/hdc3 (5)vgcreate myvg /dev/sda1 /dev/hdb2 /dev/hdc3 9. Logical Volume Manager LVs

lvcreate: creates a LV

lvremove: removes a LV

lvscan: scan for all LVs in a system

lvdisplay: shows info about a LV

lvrename, lvresize, lvreduce, lvchange

10. Logical Volume Manager LVs (1) Create a VG (2)lvcreate -L -n lvcreate -L10G -n mylv myvg It creates/dev/myvg/mylv(a link to/dev/mapper/myvg-mylv ) mkfs.ext3 /dev/myvg/mylv 11. Logical Volume Manager Snapshots

A snapshot is an image of a LV

Created instantly

Read-only / read-write (LVM2)

lvcreate -s -L -n RW: lvcreate -s -L1G -n mylv-snapshot /dev/myvg/mylv RO: lvcreate -s -L1G -n mylv-snapshot -p r /dev/myvg/mylv 12. Logical Volume Manager Snapshots

Snapshot is like a 'pointer' to the same data in original LV

Each time data in original LV is modified (or in snapshot if it was created as RW), a copy is done previously in exception table

When it becomes full it is automatically disabled

13. Logical Volume Manager Uses of Snapshots

To test: create snapshots and then use them as the main partitions

• If you don't like something, revert to original and drop the snapshots

To backup: use a snapshot to create backups

• This way, you can continue to work while backuping is done, without a problem of having an inconsistency

lvcreate -s -L1G -n snaproot /dev/vg/lvroot run-backup.sh /dev/vg/snaproot lvremove -f /dev/vg/snaproot 14. Logical Volume Manager LVM and other technologies /dev/* /dev/mapper/* /dev/* /dev/* /dev/md0 LUKS RAID 15. Logical Volume Manager LVM and other technologies /dev/* /dev/mapper/* /dev/* /dev/vg/* /dev/* /dev/* /dev/vg/* LUKS LVM 16. Logical Volume Manager LVM and other technologies /dev/* /dev/vg/* /dev/vg/* LUKS LVM 17. Logical Volume Manager LVM and other technologies /dev/vg/* /dev/* /dev/mapper/* LUKS LVM 18. Logical Volume Manager LVM and other technologies /dev/vg/* /dev/vg/* /dev/* /dev/* LUKS LVM RAID 19. Logical Volume Manager LVM and other technologies /dev/* /dev/* /dev/* /dev/vg1/* /dev/* /dev/* /dev/* /dev/vg2/* /dev/vg3/* /dev/vg3/* LUKS LUKS LVM LVM LVM 20. Logical Volume Manager My Laptop /dev/sdaA tmp home swap sbox root var music /dev/sdaB /dev/sdaC LUKS VG-CRYPT VG-UNCRYPT 21. Logical Volume Manager The End That's all, folks!