LVM (Logical Volume Manager ) in Linux

LVM:- LVM is a tool for logical volume management which is used to allocating disks, striping, mirroring and resizing logical volumes. With LVM, a hard drive or set of hard drives is allocated to one or more physical volumes.

SCENARIO

(1) Create a partition of 500 MB 

[root@CLIENT ~]# fdisk /dev/sda

The number of cylinders for this disk is set to 2714.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): n
First cylinder (2145-2714, default 2145):
Using default value 2145
Last cylinder or +size or +sizeM or +sizeK (2145-2714, default 2714): +500M
Command (m for help): t
Partition number (1-11): 11
Hex code (type L to list codes): l

 0  Empty           1e  Hidden W95 FAT1 80  Old Minix       bf  Solaris       
 1  FAT12           24  NEC DOS         81  Minix / old Lin c1  DRDOS/sec (FAT-
 2  XENIX root      39  Plan 9          82  Linux swap / So c4  DRDOS/sec (FAT-
 3  XENIX usr       3c  PartitionMagic  83  Linux           c6  DRDOS/sec (FAT-
 4  FAT16 <32M      40  Venix 80286     84  OS/2 hidden C:  c7  Syrinx        
 5  Extended        41  PPC PReP Boot   85  Linux extended  da  Non-FS data   
 6  FAT16           42  SFS             86  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS       4d  QNX4.x          87  NTFS volume set de  Dell Utility  
 8  AIX             4e  QNX4.x 2nd part 88  Linux plaintext df  BootIt        
 9  AIX bootable    4f  QNX4.x 3rd part  8e  Linux LVM       e1  DOS access    
 a  OS/2 Boot Manag 50  OnTrack DM      93  Amoeba          e3  DOS R/O       
 b  W95 FAT32       51  OnTrack DM6 Aux 94  Amoeba BBT      e4  SpeedStor     
 c  W95 FAT32 (LBA) 52  CP/M            9f  BSD/OS          eb  BeOS fs       
 e  W95 FAT16 (LBA) 53  OnTrack DM6 Aux a0  IBM Thinkpad hi ee  EFI GPT       
 f  W95 Ext'd (LBA) 54  OnTrackDM6      a5  FreeBSD         ef  EFI (FAT-12/16/
10  OPUS            55  EZ-Drive        a6  OpenBSD         f0  Linux/PA-RISC b
11  Hidden FAT12    56  Golden Bow      a7  NeXTSTEP        f1  SpeedStor     
12  Compaq diagnost 5c  Priam Edisk     a8  Darwin UFS      f4  SpeedStor     
14  Hidden FAT16 <3 61  SpeedStor       a9  NetBSD          f2  DOS secondary 
16  Hidden FAT16    63  GNU HURD or Sys ab  Darwin boot     fb  VMware VMFS   
17  Hidden HPFS/NTF 64  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE
18  AST SmartSleep  65  Novell Netware  b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 70  DiskSecure Mult bb  Boot Wizard hid fe  LANstep       
1c  Hidden W95 FAT3 75  PC/IX           be  Solaris boot    ff  BBT           
Hex code (type L to list codes): 8e
Changed system type of partition 11 to 8e (Linux LVM)

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.
 

(2) Reboot the system 

[root@CLIENT ~]# reboot

(3) Create Physical volume for LVM

[root@CLIENT ~]# pvcreate /dev/sda11
  Writing physical volume data to disk "/dev/sda11"
  Physical volume "/dev/sda11" successfully created

(4) Check status of PV created 

[root@CLIENT ~]# pvdisplay 
  --- Physical volume ---
  PV Name               /dev/sda11
  VG Name               oracle
  PV Size               486.31 MB / not usable 2.31 MB
  Allocatable           yes 
  PE Size (KByte)       4096
  Total PE              121
  Free PE               121
  Allocated PE          0
  PV UUID               rtlbU1-Qkdj-KcBs-kLQy-30AO-S8Fb-21xDIt

(5) Create Volume Group 

[root@CLIENT ~]# vgcreate oracle /dev/sda11 
  Volume group "oracle" successfully created

   

(6) Check the status of volume group oracle create

[root@CLIENT ~]# vgdisplay
  --- Volume group ---
  VG Name               oracle
  System ID            
  Format                lvm2
  Metadata Areas        1
  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                1
  Act PV                1
  VG Size               484.00 MB
  PE Size               4.00 MB
  Total PE              121
  Alloc PE / Size       0 / 0  
  Free  PE / Size       121 / 484.00 MB
  VG UUID               rEAhkH-ZV5q-N8hf-CBpJ-BgHD-l0Pf-2aBC2b
  

(7) Create Logical Volume 

[root@CLIENT ~]# lvcreate -L 480M -n database oracle
  Logical volume "database" created

(8) Check the status of LV created

[root@CLIENT ~]# lvdisplay
  --- Logical volume ---
  LV Name                /dev/oracle/database
  VG Name                oracle
  LV UUID                YXx3rp-rg3V-6MEW-9x3g-A1GP-DZT2-l0SlAN
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                480.00 MB
  Current LE             120
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1
  

(9) Format the partition from ext3 file system

[root@CLIENT ~]# mkfs.ext3 /dev/oracle/database
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
122880 inodes, 491520 blocks
24576 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67633152
60 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
        8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409

Writing inode tables: done                           
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

(10) Create the mount point for the partition

[root@CLIENT ~]# mkdir /database
[root@CLIENT ~]# mount /dev/oracle/database /database/

(11) Open the file /etc/fstab and make entry like the following

[root@CLIENT ~]# vim /etc/fstab

(12) Run command mount -a to check all mount point

[root@CLIENT ~]# mount -a

(13) Check the Disk File system of partition or mount point

[root@CLIENT ~]# df -h /database/
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/oracle-database
                      465M   11M  431M   3% /database