Use of LVM logical volumes
LVM logical volume concept address:
First of all, create a new virtual machine, we use CentOS-7-x86_64-DVD-1511 by default.
Mirror address:
link: https://pan.baidu.com/s/1Myl_GXnUg7t3OR01mCuMrQ
extraction code: 1511
①Install virtual machine, configure ip, yum source
Install virtual machine, configure ip, configure yum source address tutorial
②Add hard disk
In VMwareWorkstation, open the virtual machine settings and
finally click Finish, restart the virtual machine, and use the command to view
[root@localhost ~]# lsblk （查看磁盘）
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 19.5G 0 part
├─centos-root 253:0 0 17.5G 0 lvm /
└─centos-swap 253:1 0 2G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk
sr0 11:0 1 4G 0 rom
③Use of lvm logical volume
disk partition
[root@localhost ~]# fdisk /dev/sdb
欢迎使用 fdisk (util-linux 2.23.2)。
更改将停留在内存中，直到您决定将更改写入磁盘。
使用写入命令前请三思。
Device does not contain a recognized partition table
使用磁盘标识符 0xdf6b7d5f 创建新的 DOS 磁盘标签。
命令(输入 m 获取帮助)：p
磁盘 /dev/sdb：21.5 GB, 21474836480 字节，41943040 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0xdf6b7d5f
设备 Boot Start End Blocks Id System
命令(输入 m 获取帮助)：n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
分区号 (1-4，默认 1)：
起始 扇区 (2048-41943039，默认为 2048)：
将使用默认值 2048
Last 扇区, +扇区 or +size{
K,M,G} (2048-41943039，默认为 41943039)：+5G
分区 1 已设置为 Linux 类型，大小设为 5 GiB
命令(输入 m 获取帮助)：n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p):
Using default response p
分区号 (2-4，默认 2)：
起始 扇区 (10487808-41943039，默认为 10487808)：
将使用默认值 10487808
Last 扇区, +扇区 or +size{
K,M,G} (10487808-41943039，默认为 41943039)：+5G
分区 2 已设置为 Linux 类型，大小设为 5 GiB
命令(输入 m 获取帮助)：p
磁盘 /dev/sdb：21.5 GB, 21474836480 字节，41943040 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0xdf6b7d5f
设备 Boot Start End Blocks Id System
/dev/sdb1 2048 10487807 5242880 83 Linux
/dev/sdb2 10487808 20973567 5242880 83 Linux
命令(输入 m 获取帮助)：w
The partition table has been altered!
Calling ioctl() to re-read partition table.
正在同步磁盘。
Check the disk again and find a new partition
Create a physical volume for the new partition
[root@localhost ~]# pvcreate /dev/sdb1 /dev/sdb2 （对俩新分区创建新的物理卷）
Physical volume "/dev/sdb1" successfully created
Physical volume "/dev/sdb2" successfully created
[root@localhost ~]# pvs （查看简单物理卷信息）
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- 19.51g 40.00m
/dev/sdb1 lvm2 --- 5.00g 5.00g
/dev/sdb2 lvm2 --- 5.00g 5.00g
[root@localhost ~]# pvdisplay （查看详细物理卷信息）
--- Physical volume ---
PV Name /dev/sda2
VG Name centos
PV Size 19.51 GiB / not usable 3.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 4994
Free PE 10
Allocated PE 4984
PV UUID L4L1ve-YRxL-AV6j-evy0-WqWe-AqOa-6lvuAX
"/dev/sdb2" is a new physical volume of "5.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb2
VG Name
PV Size 5.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID auisMi-9Hr2-KkK0-eq86-7sC7-UB5U-J1JaBS
"/dev/sdb1" is a new physical volume of "5.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 5.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 3OW1BR-W3jq-Lge0-YenU-ukJT-8Sha-ISOSEf
Create volume group
[root@localhost ~]# vgcreate myvg /dev/sdb[1-2] （对俩物理卷创建卷组）
Volume group "myvg" successfully created
[root@localhost ~]# vgs （查看简单卷组信息）
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- 19.51g 40.00m
myvg 2 0 0 wz--n- 9.99g 9.99g
[root@localhost ~]# vgdisplay （查看详细卷组信息）
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 19.51 GiB
PE Size 4.00 MiB
Total PE 4994
Alloc PE / Size 4984 / 19.47 GiB
Free PE / Size 10 / 40.00 MiB
VG UUID 2lZ6d7-4zFf-vY1X-0Qe9-86Ca-q1vV-5ZPW0e
--- Volume group ---
VG Name myvg
System ID
Format lvm2
Metadata Areas 2
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 2
Act PV 2
VG Size 9.99 GiB
PE Size 4.00 MiB
Total PE 2558
Alloc PE / Size 0 / 0
Free PE / Size 2558 / 9.99 GiB
VG UUID 3xuvpY-xxcC-aFn9-tYmP-DFxj-T3TD-1DsDrR
When multiple physical volumes are combined into a volume group, LVM will do a similar formatting work on all physical volumes, cutting each physical volume into a piece of space, and this piece of space is called PE ( Physical Extent), its default size is 4MB.
Due to the limitation of the kernel, a logical volume (Logic Volume) can only contain 65536 PEs (PhysicalExtent) at most, so the size of a PE determines the maximum capacity of the logical volume, and a PE of 4MB determines the maximum capacity of a single logical volume. 256 GB. If you want to use a logical volume larger than 256 Gb, you need to specify a larger PE when creating a volume group.
Delete the volume group and recreate it
[root@localhost ~]# vgremove myvg (删除卷组)
Volume group "myvg" successfully removed
[root@localhost ~]# vgcreate -s 16m myvg /dev/sdb[1-2] （创建16MB的PE）
Volume group "myvg" successfully created
[root@localhost ~]# vgdisplay （查看信息，可以看到PE成功便成16MB）
Add physical volume
Add a physical volume to the volume group myvg, and then divide a /dev/sdb3 partition on /dev/sdb, and add the partition to the volume group myvg.
[root@localhost ~]# fdisk /dev/sdb
欢迎使用 fdisk (util-linux 2.23.2)。
更改将停留在内存中，直到您决定将更改写入磁盘。
使用写入命令前请三思。
命令(输入 m 获取帮助)：n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p):
Using default response p
分区号 (3,4，默认 3)：
起始 扇区 (20973568-41943039，默认为 20973568)：
将使用默认值 20973568
Last 扇区, +扇区 or +size{
K,M,G} (20973568-41943039，默认为 41943039)：+5G
分区 3 已设置为 Linux 类型，大小设为 5 GiB
命令(输入 m 获取帮助)：w
The partition table has been altered!
Calling ioctl() to re-read partition table.
正在同步磁盘。
Add the created /dev/sdb3 to the myvg volume group. In the process of adding, /dev/sdb3 will be automatically created as a physical volume
[root@localhost ~]# vgextend myvg /dev/sdb3
Physical volume "/dev/sdb3" successfully created
Volume group "myvg" successfully extended
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- 19.51g 40.00m
myvg 3 0 0 wz--n- 14.95g 14.95g
Create logical volume
[root@localhost ~]# lvcreate -L +5G -n mylv myvg （创建逻辑卷）
Logical volume "mylv" created.
[root@localhost ~]# lvs （查看逻辑卷）
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- 17.47g
swap centos -wi-ao---- 2.00g
mylv myvg -wi-a----- 5.00g
[root@localhost ~]# lvscan （扫描lv逻辑卷）
ACTIVE '/dev/myvg/mylv' [5.00 GiB] inherit
ACTIVE '/dev/centos/swap' [2.00 GiB] inherit
ACTIVE '/dev/centos/root' [17.47 GiB] inherit
Format the logical volume mylv using the ext4 file system
[root@localhost ~]# mkfs.ext4 /dev/mapper/myvg-mylv
mke2fs 1.42.9 (28-Dec-2013)
文件系统标签=
OS type: Linux
块大小=4096 (log=2)
分块大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1310720 blocks
65536 blocks (5.00%) reserved for the super user
第一个数据块=0
Maximum filesystem blocks=1342177280
40 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
Allocating group tables: 完成
正在写入inode表: 完成
Creating journal (32768 blocks): 完成
Writing superblocks and filesystem accounting information: 完成
Verify logical volume
Mount the logical volume mylv under /mnt and verify
[root@localhost ~]# mount /dev/mapper/myvg-mylv /mnt/
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 18G 855M 17G 5% /
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.7M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sda1 497M 125M 373M 25% /boot
tmpfs 378M 0 378M 0% /run/user/0
/dev/mapper/myvg-mylv 4.8G 20M 4.6G 1% /mnt
Expand logical volume
[root@localhost ~]# lvextend -L +1G /dev/mapper/myvg-mylv （对逻辑卷扩容1G）
Size of logical volume myvg/mylv changed from 5.00 GiB (320 extents) to 6.00 GiB (384 extents).
Logical volume mylv successfully resized.
You can see that the logical volume information shows 6GB but there is no change in the mount information, so the file system needs to be expanded.
[root@localhost ~]# resize2fs /dev/mapper/myvg-mylv
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mapper/myvg-mylv is mounted on /mnt; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/mapper/myvg-mylv is now 1572864 blocks long.
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 18G 855M 17G 5% /
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.7M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sda1 497M 125M 373M 25% /boot
tmpfs 378M 0 378M 0% /run/user/0
/dev/mapper/myvg-mylv 5.8G 20M 5.5G 1% /mnt
This is a success!