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Logical Volume Manager. An Introduction
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Logical Volume Manager. An Introduction

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Introduction to LVM and how it is related with other modules like LUKS.

Introduction to LVM and how it is related with other modules like LUKS.

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  • 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/<partition>
  • 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<size> -n <name> <vg> 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<size> -n <name> <lv> 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!