Thursday 2 February 2017

LVM:Logical Volume Management

LVM stands for Logical Volume Management. It is a system of managing logical volumes, or filesystems, that is much more advanced and flexible than the traditional method of partitioning a disk into one or more segments and formatting that partition with a filesystem.
  
LVM Implementation 

 [root@highperfrawdb scripts]# ls -la /dev/xvd*
brw-rw---- 1 root disk 202, 16 Jun  8 10:16 /dev/xvdb
brw-rw---- 1 root disk 202, 17 Jun  8 10:16 /dev/xvdb1
brw-rw---- 1 root disk 202, 18 Jun  8 10:16 /dev/xvdb2
brw-rw---- 1 root disk 202, 19 Jun  8 10:16 /dev/xvdb3
brw-rw---- 1 root disk 202, 32 Jun  8 15:39 /dev/xvdc
brw-rw---- 1 root disk 202, 48 Jun  8 15:39 /dev/xvdd
brw-rw---- 1 root disk 202, 64 Jun  8 15:39 /dev/xvde
brw-rw---- 1 root disk 202, 80 Jun  8 15:39 /dev/xvdf


[root@highperfrawdb scripts]# vgcreate /dev/vgstripe /dev/xvdc /dev/xvdd /dev/xvde /dev/xvdf
  Physical volume "/dev/xvdc" successfully created
  Physical volume "/dev/xvdd" successfully created
  Physical volume "/dev/xvde" successfully created
  Physical volume "/dev/xvdf" successfully created
  Volume group "vgstripe" successfully created


[root@highperfrawdb scripts]# lvcreate -i4 -L395G -n lvstrip vgstripe
  Using default stripesize 64.00 KiB
  Logical volume "lvstrip" created


[root@highperfrawdb scripts]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/vgstripe/lvstrip
  LV Name                lvstrip
  VG Name                vgstripe
  LV UUID                b8j9js-61Ib-0W8e-XUcK-z26d-eQG7-OGXjPO
  LV Write Access        read/write
  LV Creation host, time highperfrawdb, 2016-06-08 15:43:49 -0400
  LV Status              available
  # open                 0
  LV Size                395.00 GiB
  Current LE             101120
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     1024
  Block device           252:0
   


[root@highperfrawdb scripts]# mkfs -t ext4 /dev/vgstripe/lvstrip
mke2fs 1.43-WIP (20-Jun-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=16 blocks, Stripe width=64 blocks
25886720 inodes, 103546880 blocks
5177344 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
3160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
    4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
    102400000

Allocating group tables: done                           
Writing inode tables: done                           
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done     



[root@highperfrawdb scripts]# mkdir /lvs

 
[root@highperfrawdb scripts]# mount /dev/vgstripe/lvstrip /lvs

 
[root@highperfrawdb scripts]# cd /lvs


[root@highperfrawdb lvs]# ls
lost+found



[root@highperfrawdb ~]# cat /etc/fstab

#
# /etc/fstab
# Created by anaconda on Wed Apr 15 18:13:53 2015
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=ac69bdf3-37be-47f2-9d59-6d4c672f98cc /                       ext4    defaults        1 1
UUID=947fa69d-3925-4738-a6c0-27d00f5c4f96 /boot                   ext4    defaults        1 2
UUID=d24de279-f4f1-46ae-aa3b-5297bd258dcc swap                    swap    defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/vgstripe/lvstripe      /lvs                   ext4    defaults        0 0



[root@highperfrawdb ~]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/xvdb3             25G   20G  4.5G  82% /
/dev/xvdb1            477M  148M  300M  34% /boot
/dev/mapper/vgstripe-lvstrip
                      389G   71M  369G   1% /lvs



More details 
 

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