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Today, the editor will share with you the relevant knowledge points about how to quickly create LVM under CentOS7. The content is detailed and the logic is clear. I believe most people still know too much about this knowledge, so share this article for your reference. I hope you can get something after reading this article.

LVM is a logic layer added between the hard disk partition and the file system, shielding the underlying hard disk partition layout for the file system, and providing an abstract disk volume to establish the file system on the disk volume. The administrator can use LVM to dynamically resize the file system without repartitioning the hard disk, and the file system managed by LVM can span the physical hard disk.

Environment: CentOS7 virtual machine with a 2G hard disk mounted

2. Configuration process:

2. Configuration process:

1. Partition the hard disk:

Create three partitions, the first two 512m, the last one has a default size of more than 1G, and the last one specifies the size by default, depending on your environment. It would be nice to change the partitions to Linux LVM format.

Command (m for help): P / / View partition table

Disk / dev/sdb: 2147 MB, 2147483648 bytes, 4194304 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0xbe89015f

Device Boot Start End Blocks Id System

Command (m for help): n / / create a partition

Partition type:

P primary (0 primary, 0 extended, 4 free)

E extended

Select (default p): P / / primary partition

Partition number (1-4, default 1): 1

First sector (2048-4194303, default 2048):

Using default value 2048

Last sector, + sectors or + size {Kjens Mpeng G} (2048-4194303, default 4194303): + 512m / / specified size

Partition 1 of type Linux and of size 512 MiB is set

Command (m for help): n

Partition type:

P primary (1 primary, 0 extended, 3 free)

E extended

Select (default p): P

Partition number (2-4, default 2): 2

First sector (1050624-4194303, default 1050624):

Using default value 1050624

Last sector, + sectors or + size {KMagneMMagneG} (1050624-4194303, default 4194303): + 512m

Partition 2 of type Linux and of size 512 MiB is set

Command (m for help): n

Partition type:

P primary (2 primary, 0 extended, 2 free)

E extended

Select (default p): P

Partition number (3pr 4, default 3):

First sector (2099200-4194303, default 2099200):

Using default value 2099200

Last sector, + sectors or + size {KMagneMje G} (2099200-4194303, default 4194303): / / all sizes left by default

Using default value 4194303

Partition 3 of type Linux and of size 1023 MiB is set

Command (m for help): W / / Save exit

The partition table has been altered!

Calling ioctl () to re-read partition table.

Syncing disks.

[root@localhost ~] # fdisk / dev/sdb

Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.

Be careful before using the write command.

Command (m for help): P

Disk / dev/sdb: 2147 MB, 2147483648 bytes, 4194304 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0xbe89015f

Device Boot Start End Blocks Id System

/ dev/sdb1 2048 1050623 524288 83 Linux

/ dev/sdb2 1050624 2099199 524288 83 Linux

/ dev/sdb3 2099200 4194303 1047552 83 Linux

Command (m for help): t / / modify partition type

Partition number (1-3, default 3): 1 / / Select partition

Hex code (type L to list all codes): 8e / / change to Linux LVM type partition, 8e is the partition code, l can see

Changed type of partition 'Linux' to' Linux LVM'

Command (m for help): t

Partition number (1-3, default 3): 2

Hex code (type L to list all codes): 8e

Changed type of partition 'Linux' to' Linux LVM'

Command (m for help): t

Partition number (1-3, default 3): 3

Hex code (type L to list all codes): 8e

Changed type of partition 'Linux' to' Linux LVM'

Command (m for help): P

Disk / dev/sdb: 2147 MB, 2147483648 bytes, 4194304 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0xbe89015f

Device Boot Start End Blocks Id System

/ dev/sdb1 2048 1050623 524288 8e Linux LVM

/ dev/sdb2 1050624 2099199 524288 8e Linux LVM

/ dev/sdb3 2099200 4194303 1047552 8e Linux LVM

Command (m for help): W

The partition table has been altered!

Calling ioctl () to re-read partition table.

Syncing disks.

2. Create a physical volume:

Commands: pv series command

Root@localhost ~] # pv

Pvchange pvcreate pvmove pvresize pvscan

Pvck pvdisplay pvremove pvs

Create physical volumes: select the partition you want to create

[root@localhost ~] # pvcreate / dev/sdb {1J 2pm 3} / / use three sdb1,sdb2,sdb3 partitions to create physical volumes

Physical volume "/ dev/sdb1" successfully created.

Physical volume "/ dev/sdb2" successfully created.

Physical volume "/ dev/sdb3" successfully created.

Simply view the physical volume:

[root@localhost ~] # pvs

PV VG Fmt Attr PSize PFree

/ dev/sdb1 lvm2-512.00m 512.00m

/ dev/sdb2 lvm2-512.00m 512.00m

/ dev/sdb3 lvm2-1023.00m 1023.00m

View in detail:

[root@localhost ~] # pvdisplay

"/ dev/sdb1" is a new physical volume of "512.00 MiB"

-NEW Physical volume-

PV Name / dev/sdb1

VG Name

PV Size 512.00 MiB

Allocatable NO

PE Size 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID 413TpT-NC3F-ch4r-3xsy-TW10-P3Rr-qT6dm5

"/ dev/sdb3" is a new physical volume of "1023.00 MiB"

-NEW Physical volume-

PV Name / dev/sdb3

VG Name

PV Size 1023.00 MiB

Allocatable NO

PE Size 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID DDu25l-PBlg-sRJY-qgl1-Io3s-ezmj-KVuZCT

"/ dev/sdb2" is a new physical volume of "512.00 MiB"

-NEW Physical volume-

PV Name / dev/sdb2

VG Name

PV Size 512.00 MiB

Allocatable NO

PE Size 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID Z5QKKi-RoKG-MZ1b-ed3s-Ibgg-eyAr-PDK0kV

PE (physical extent): the physical area is the smallest storage unit available for allocation in the physical volume. The physical area size is specified when the volume group is established. Once it is determined that the physical area size of all physical volumes in the same volume group cannot be changed, the physical area size of all physical volumes in the same volume group needs to be the same. After the new pv is added to the vg, the size of the pe automatically changes to the pe size defined in the vg.

LE (logical extent): a logical region is the smallest storage unit in a logical volume that can be allocated, and the size of the logical area depends on the size of the physical area in the volume group in which the logical volume resides.

Volume group description area: the volume group description area exists in each physical volume and is used to describe all the information such as the physical volume itself, the volume group to which the physical volume belongs, the logical volume in the volume group, the allocation of physical areas in the logical volume, and so on. It is established when the physical volume is established using pvcreate.

3. Create a volume group: vg series command

[root@localhost ~] # vg

Vgcfgbackup vgconvert vgextend vgmknodes vgs

Vgcfgrestore vgcreate vgimport vgreduce vgscan

Vgchange vgdisplay vgimportclone vgremove vgsplit

Vgck vgexport vgmerge vgrename

Create a volume group with an optional name

[root@localhost ~] # vgremove myvg

Volume group "myvg" successfully removed

[root@localhost ~] # vgcreate-s 16m myvg / dev/sdb {1rem 2pm 3}

Volume group "myvg" successfully created

[root@localhost ~] # vgs

VG # PV # LV # SN Attr VSize VFree

Myvg 3 0 0 wz-n- 1.95g 1.95g

[root@localhost ~] # vgdisplay

-Volume group-

VG Name myvg

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 1.95 GiB

PE Size 16.00 MiB

Total PE 125

Alloc PE / Size 0 / 0

Free PE / Size 125 / 1.95 GiB

VG UUID 3Eu9GX-U4ip-mxSF-zibe-7802-8Suh-38b4dG

Create a logical volume

[root@localhost ~] # lvcreate-L 1.4G-n mylv myvg / dev/sdb {1pm 3} / /-L specifies the size,-n specifies the name

Rounding up size to full physical extent 1.41 GiB

Logical volume "mylv" created.

[root@localhost ~] # lvs / / simply view information

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

Mylv myvg-wi-a-- 1.41g

[root@localhost ~] # lvdisplay / / View more information

-Logical volume-

LV Path / dev/myvg/mylv

LV Name mylv

VG Name myvg

LV UUID coMhuV-ywOe-FEbm-SkQd-upfQ-0era-cCfqHy

LV Write Access read/write

LV Creation host, time localhost.localdomain, 2017-05-17 16:30:37 + 0800

LV Status available

Open 0

LV Size 1.41 GiB

Current LE 90

Segments 2

Allocation inherit

Read ahead sectors auto

Currently set to 8192

Block device 253:0

Format:

[root@localhost ~] # mkfs.ext4 / dev/myvg/mylv

Mke2fs 1.42.9 (28-Dec-2013)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=0 blocks, Stripe width=0 blocks

92160 inodes, 368640 blocks

18432 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=377487360

12 block groups

32768 blocks per group, 32768 fragments per group

7680 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912

Allocating group tables: done

Writing inode tables: done

Creating journal (8192 blocks): done

Writing superblocks and filesystem accounting information: done

3. Mounting and using

View the physical location:

[root@localhost ~] # ll / dev/myvg/mylv

Lrwxrwxrwx 1 root root 7 May 17 16:30 / dev/myvg/mylv->.. / dm-0

Mount to a directory and read and write:

[root@localhost ~] # mount / dev/myvg/mylv / mnt

[root@localhost ~] # mkdir / mnt/test

[root@localhost ~] # ls / mnt/ > / mnt/test/test.txt

[root@localhost ~] # cat / mnt/test/test.txt

Lost+found

Test

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