===================
Linux LVM partition
===================

Volumegroups
============
Volume groups are nothing but a pool of storage that consists of one or more physical volumes. Once you create the physical volume, you can create the volume group (VG) from these physical volumes (PV).

.. image:: images/LVM_original_description.png


.. literalinclude:: lvm_vagrantfile

pvcreate,vgcreate,lvcreate
**************************
::

	vagrant ssh server1
    sudo su -
    fdisk -l

	// แสดง disk ทีี่เชื่อมกับ server1
	Disk /dev/vdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
	Units = sectors of 1 * 512 = 512 bytes
	Sector size (logical/physical): 512 bytes / 512 bytes
	I/O size (minimum/optimal): 512 bytes / 512 bytes


	Disk /dev/vdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
	Units = sectors of 1 * 512 = 512 bytes
	Sector size (logical/physical): 512 bytes / 512 bytes
	I/O size (minimum/optimal): 512 bytes / 512 bytes


	Disk /dev/vdd: 21.5 GB, 21474836480 bytes, 41943040 sectors
	Units = sectors of 1 * 512 = 512 bytes
	Sector size (logical/physical): 512 bytes / 512 bytes
	I/O size (minimum/optimal): 512 bytes / 512 bytes

    //create phisical volume
    # pvcreate /dev/vdb
    Physical volume "/dev/vdb" successfully created

    # pvcreate /dev/vdc
    Physical volume "/dev/vdc" successfully created

    # pvcreate /dev/vdd
    Physical volume "/dev/vdd" successfully created


    # vgcreate myvol  /dev/vdb /dev/vdc /dev/vdd
    Volume group "myvol" successfully created

ตรวจสอบด้วยคำสั่ง vgdisplay
::

	  # vgdisplay

	  --- Volume group ---
	  VG Name               myvol
	  System ID
	  Format                lvm2
	  Metadata Areas        3
	  Metadata Sequence No  1
	  VG Access             read/write
	  VG Status             resizable
	  MAX LV                0
	  Cur LV                0
	  Open LV               0
	  Max PV                0
	  Cur PV                3
	  Act PV                3
	  VG Size               59.99 GiB
	  PE Size               4.00 MiB
	  Total PE              15357
	  Alloc PE / Size       0 / 0
	  Free  PE / Size       15357 / 59.99 GiB
	  VG UUID               5UZdx5-6m3S-Bh7O-yMWk-A3gS-dJey-N8Ndd1

การใช้งาน volumegroup ได้โดยการแบ่งพื้นที่การใช้งาน ด้วยคำสั่ง lvcreate
::

		# lvcreate -l 5 -n data1 myvol
  	Logical volume "data1" created.

    # lvdisplay

  	--- Logical volume ---
  	LV Path                /dev/myvol/data1
  	LV Name                data1
  	VG Name                myvol
  	LV UUID                cVlf5O-SHa5-hB6Y-pSGK-cXaG-9Yok-bMGIxn
  	LV Write Access        read/write
  	LV Creation host, time server1, 2016-07-05 02:37:21 -0400
  	LV Status              available
  	# open                 0
  	LV Size                20.00 MiB
  	Current LE             5
  	Segments               1
  	Allocation             inherit
  	Read ahead sectors     auto
  	- currently set to     8192
  	Block device           253:2

Format สร้าง file system และ  สร้าง mount point สำหรับการใช้้งาน
::

		# mkfs.ext4 /dev/myvol/data1
    # mkdir /data1
    # mount /dev/myvol/data1  /data1
    # cd /data1
    # touch text.txt