How to Manage and Create LVM on CentOS 7
To Manage and Create LVM on CentOS 7
Logical Volumes Management (also known as LVM), which have become a default for the installation of most (if not all) Linux distributions, have numerous advantages over traditional partitioning management. Perhaps the most distinguishing feature of LVM is that it allows logical divisions to be resized (reduced or increased) at will without much hassle.
The structure of the LVM consists of:
- One or more entire hard disks or partitions are configured as physical volumes (PVs).
- A volume group (VG) is created using one or more physical volumes. You can think of a volume group as a single storage unit.
- Multiple logical volumes can then be created in a volume group. Each logical volume is somewhat equivalent to a traditional partition &ndash with the advantage that it can be resized at will as we mentioned earlier.
- One of the most useful and helpful technology to linux system administrator is Linux Logical Volume Manager(LVM), version 2 (or LVM 2).
- LVM is a widely-used technique and extremely flexible disk management scheme for deploying logical rather than physical storage. With LVM, system administrator can easily resize and extend the logical drive when it is required.
Creating LVM
First, you need to check current Disk status and for that, you need to run the following command.
[root@linuxhelp11 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
├─sda1 8:1 0 500M 0 part /boot
├─sda2 8:2 0 2G 0 part [SWAP]
└─sda3 8:3 0 25G 0 part /
sdb 8:16 0 20G 0 disk
Once it is done, you need to create new Partition by making use of the following command.
Here n is given to denote the creation of new partition.
l => will display all types of partitioning
[root@linuxhelp11 ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
.
.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +10G
Partition 1 of type Linux and of size 10 GiB is set
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): l
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 < 32M 40 Venix 80286 85 Linux extended c7 Syrinx
5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data
6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility
8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt
9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access
a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT
f W95 Ext' d (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor
14 Hidden FAT16 < 3 61 SpeedStor ab Darwin boot f2 DOS secondary
16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ 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
1e Hidden W95 FAT1 80 Old Minix
Here select type for LVM
Hex code (type L to list all codes): 8e
Changed type of partition ' Linux' to ' Linux LVM'
Don’ t forget to save the changes by making use of the w option.
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
Once all the modification is done in the partition, you can restart it by making use of the following command.
[root@linuxhelp11 ~]# partprobe
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
You can now create the display created partition by making use of the following command.
[root@linuxhelp11 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
.
.
sdb 8:16 0 20G 0 disk
" └─sdb1 8:17 0 10G 0 part "
You should then create Physical volume.
[root@linuxhelp11 ~]# pvcreate /dev/sdb1
Physical volume " /dev/sdb1" successfully created.
And then create Volume group.
[root@linuxhelp11 ~]# vgcreate test /dev/sdb1
Volume group " test" successfully created
After which you need to create a Logical volume as well.
[root@linuxhelp11 ~]# lvcreate -n check -L 8G test
Logical volume " check" created.
You can have the information displayed after creating LVM.
[root@linuxhelp11 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
.
.
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 10G 0 part
└─test-check 253:0 0 8G 0 lvm
And then make directory for mounting.
[root@linuxhelp11 /]# mkdir /test
Also, set format of partition.
[root@linuxhelp11 /]# mkfs.xfs /dev/test/check
You should now check the BlockID
[root@linuxhelp11 /]# blkid /dev/sda1: UUID=" b7621033-beea-4ad3-a696-c59973e10215" TYPE=" xfs" . . " dev/mapper/test-check: UUID=" 9da1920c-978d-4c1e-bc3b-1307789e07fc" TYPE=" xfs" " [root@linuxhelp11 /]# vim /etc/fstab
And then update mounting.
[root@linuxhelp11 /]# mount -a
And then, display after mounting Partitioning by making use of the following command.
[root@linuxhelp11 /]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
.
.
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 10G 0 part
└─test-check 253:0 0 8G 0 lvm /test
Managing and removing LVM
LVM has been created, now we shall manage it. Let’ s un-mount a partition by making use of the following command.
root@linuxhelp11 /]# umount /dev/test/check
And to clear entry of fstab you should run the following command.
[root@linuxhelp11 /]# vim /etc/fstab
You can display information after unmount partition.
[root@linuxhelp11 /]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
.
.
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 10G 0 part
└─test-check 253:0 0 8G 0 lvm
If you want to remove Logical volume, run the following command.
[root@linuxhelp11 /]# lvremove /dev/test/check
Do you really want to remove active logical volume test/check? [y/n]: y
Logical volume " check" successfully removed
You can remove volume group by making use of the following command.
[root@linuxhelp11 /]# vgremove /dev/test
Volume group " test" successfully removed
And then, remove Physical volume by making use of the following command.
[root@linuxhelp11 /]# pvremove /dev/sdb1
Labels on physical volume " /dev/sdb1" successfully wiped.
You can display information after removing LVM by making use of the following command.
[root@linuxhelp11 /]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
.
.
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 10G 0 part
If you want to delete a partition, make use of the following command.
[root@linuxhelp11 /]# fdisk /dev/sdb Welcome to fdisk (util-linux 2.23.2). . . Command (m for help): d Selected partition 1 Partition 1 is deleted
Make sure you save changes for partitioning by using the following option.
Command (m for help): w
The partition table has been altered!
.
.
Syncing disks.
You shall restart the Disk partition
[root@linuxhelp11 /]# partprobe
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
And then, you shall display information after remove partitioning.
[root@linuxhelp11 /]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 35G 0 disk
.
.
sdb 8:16 0 20G 0 disk
With this, the tutorial on creating, managing and removing LVM on CentOS 7 comes to an end.
One or more entire hard disks or partitions are configured as physical volumes (PVs).
A volume group (VG) is created using one or more physical volumes. You can think of a volume group as a single storage unit.
Multiple logical volumes can then be created in a volume group. Each logical volume is somewhat equivalent to a traditional partition &ndash with the advantage that it can be resized at will as we mentioned earlier.
One of the most useful and helpful technology to linux system administrator is Linux Logical Volume Manager(LVM), version 2 (or LVM 2).
LVM is a widely-used technique and extremely flexible disk management scheme for deploying logical rather than physical storage. With LVM, system administrator can easily resize and extend the logical drive when it is required.
#lsblk