Linux Learning - Logical Volume Managment (LVM)

###Logical Volume Managment (LVM)###
Features: 
 1. Volume sets - aggreate storage from disparate sources
 2. Resize storage on-the-fly
 3. Provision storage as necessary


Tasks:
 1. LVM Storage Hierarchy
  Logical Volume - configure file system at this level
   - Volume Groups - represents one or more physical volumes
    - Physical Volumes: (i.e. /dev/sdb4, /dev/sdc3, etc.) - partition, using fdisk or parted: LVM type (8e)


 2. Create LVM Storage Hierarchy - 6-Steps
   a. Create LVM partitions on available disks
   a1. 'parted /dev/sdb'
   a2. 'mkpart primary start end'  
   a3. 'set partition_num lvm on'
   a4. 'reboot'


   b. 'pvcreate /dev/sdb4 /dev/sdc3' - create physical LVM volumes from partitions
    b1. 'pvdisplay'
   c. 'vgcreate volgroupvar /dev/sdb4 /dev/sdc3' - allocates both volumes to the volume group
   d. 'lvcreate -L 5GB -n logvolvar volgroupvar'
   e. 'mke2fs -t ext4 -j /dev/volgroupvar/logvolvar' - overlays EXT4 FS on LVM volume
   f. 'mkdir /lvmvar1 && mount /dev/volgroupvar/logvolvar /lvmvar1'
   g. Update: '/etc/fstab' for persistence




 3. Resize LVMs
  a. 'lvresize -L 6GB /dev/volgroupvar/logvolvar'
  b. 'resize2fs /dev/volgroupvar/logvolvar 6G'
  c. 'lvresize -L 4GB /dev/volgroupvar/logvolvar'
  d. 'resize2fs /dev/volgroupvar/logvolvar 4G'
Note: Reductions will likely return errors resulting in re-provisioning of the FS


 4. Rename Logical Volume
  a. 'lvrename volgroupvar logvolvar logvolopt' - renames volume, NOT volume group
  b. 'lvresize -L 6GB /dev/volgroupvar/logvolopt' - restores to 6GB


 5. Rename Volume Group
  a. 'vgrename volgroupvar volgroupopt' - renames the volume group
  b. update: '/etc/fstab' - to reflect volume group name change


 6. Assign more partitions(storage) to LVM
  a. 'parted /dev/sdc'
  b. 'mkpart primary 16.1GB 26.1GB'
  c. 'set 4 lvm on'
  d. 'pvcreate /dev/sdc4' - assigns LVM partition to LVM management
  e. 'vgextend volgroupopt /dev/sdc4' - extends volume group: 'volgroupopt'
  f. 'lvresize -L 15GB /dev/volgroupopt/logvolopt' - online resize
  g. 'resize2fs /dev/volgroupopt/logvolopt 15G' - online resize


 7. LVM GUI
  a. 'system-config-lvm'
  b. 'ssh -X [email protected]' - redirects X.org session back to local GUI
  c. Extend storage of: '/dev/volgroupopt/logvolopt' to: 16GB
Note: GUI will send appropriate commands to system to:
  a. Resize logical volume (logvolopt)
  b. Resize EXT4 FS to appropriate size


 8. Recreate LVM hierarchy
  a. Unmount any partitions tied to: '/dev/sd[bc]'
  b. 'parted /dev/sdb' - remove partitions & create new LVM partitions 
  c. 'init 6' - reboot
  d. Use: 'system-config-lvm' to create volume group from: '/dev/sdb1' & '/dev/sdc1'
  e. Create logical volume: 'logvolopt'
  f. Mount at: '/opt'