====== Logical Volume Manager ======

  * [[http://www.cyberciti.biz/tips/consistent-backup-linux-logical-volume-manager-snapshots.html|Consistent backup with Linux Logical Volume Manager (LVM) snapshots]]
  * [[http://www.howtoforge.com/encrypted-root-lvm|Encrypted root LVM]]

===== Example usage =====

Start by looking at our existing disks

	cat /proc/scsi/
	dmesg |grep sd
	

Next, partition the new disks using fdisk

	fdisk /dev/sdb
	

  * **p** to Print the existing table (should be blank)
  * **n** to create a new partition
  * **t** to change partition system ID to 8e (Linux LVM)
  * **w** to write new table to disk


Repeat for /dev/sdc
Create the physical volumes

	pvcreate /dev/sdb1
	pvcreate /dev/sdc1
	


//NOTE: You can create multiple PVs on a single disk, but it is not recommended. Show existing Physical Volumes//

	pvscan
	

Show Volume Groups

	vgscan (should return nothing)
	

Create a Volume Group from the Physical Volumes

	vgcreate opt_vg /dev/sdb1 /dev/sdc1
	

//NOTE: You can specify PE size in vgcreate. Default is 4M. You'd use larger PE sizes for LVs greater than 256G. 65K PEs per LV.//

Show Volume Groups

	vgscan (now shows the VG we created)
	

Display information about the VG

	vgdisplay 
	

Create a Logical Volume within the VG

	lvcreate -l num_of_extents -n opt_lv opt_vg
	lvcreate -L 100M -n opt_lv opt_vg
	lvcreate -L 100M -n opt_lv -i num_stripes opt_vg
	lvcreate -L 100M -n opt_lv opt_vg [PhysicalVolumePath]
	

Display information about the LV

	lvdisplay
	lvdisplay -m (Show maps. Compare striped vs un-striped)
	

Create a mount point

	mkdir /opt/foo1
	mkdir /opt/striped
	

Create a filesystem

	mkfs.ext3 /dev/opt_vg/opt_lv
	mkfs.ext3 /dev/opt_vg/striped_lv
	

Mount the filesystems

	mount /dev/opt_vg/opt_lv
	df -h 
	

===== Growing a Filesystem =====
==== Grow an EXT2/3 filesystem (with unmount) ====

Unmount the FS

	umount /mnt/lvm_filesystem
	

Extend the LV

	lvresize -l +50 /dev/opt_vg/opt_lv
	lvresize -L +200M /dev/opt_vg/opt_lv
	

fsck the filesystem

	e2fsck -f /dev/opt_vg/opt_lv
	

Resize the filesystem

	resize2fs /dev/opt_vg/opt_lv
	

Remount the filesystem

	mount -t ext3 /dev/opt_vg/opt_lv /mnt/lvm_filesystem

==== Grow an EXT2/3 filesystem (without unmount) ====

Extend the LV

	lvresize -l +50 /dev/opt_vg/opt_lv
	lvresize -L +200M /dev/opt_vg/opt_lv
	

Grow the filesystem

	ext2online /mnt/lvm_filesystem (using mount path)
	ext2online /dev/opt_vg/opt_lv (using device)
	

Grow a ReiserFS filesystem
Create a ReiserFS on /dev/opt_vg/striped_lv

	mkreiserfs /dev/opt_vg/striped_lv
	

Mount the FS

	df -h
	lvresize -L +50M /dev/opt_vg/striped_lv
	resize_reiserfs -f /dev/opt_vg/striped_lv
	df -h
	

Add a Physical Volume to a VG

	vgextend vgname /path/to/PV

===== Resizing crypted LVM  =====

   cryptsetup -c aes -h ripemd160 -s 256 create home /dev/disk_array/data
   pvcreate /dev/hde1
   vgextend disk_array /dev/hde1
   lvresize -L +114G /dev/disk_array/data
   cryptsetup resize home
   resize_reiserfs -s +114G /dev/mapper/home