LVM 相关知识
一、示例图
二、概念
| 名词 | 全称 | 释义 |
|---|---|---|
| PV | Physical Volume | 物理硬盘、硬盘分区或者RAID磁盘阵列，先要创建pv |
| VG | Volume Group | 卷组建立在物理卷之上，一个卷组可以包含多个物理卷，而且在卷组创建之后也可以继续向其中添加新的物理卷。 |
| LV | Logical Volume | 逻辑卷是用卷组中空闲的资源建立的，并且逻辑卷在建立后可以动态地扩展或缩小空间。 |
| PE | Physical Extent | 基本单元，就像是存储数据的块大小 |
三、LVM 命令
1.如果没有需要安装
[root@hdss7-200 ~]# yum -y install lvm2
| 功能/命令 | 物理卷管理 | 卷组管理 | 逻辑卷管理 |
|---|---|---|---|
| 扫描 | pvscan | vgscan | lvscan |
| 建立 | pvcreate | vgcreate | lvcreate |
| 显示 | pvdisplay | vgdisplay | lvdisplay |
| 删除 | pvremove | vgremove | lvremove |
| 扩展 | vgextend | lvextend | |
| 缩小 | vgreduce | lvreduce |
四、创建逻辑卷
1.第一步：初始化PV
[root@hdss7-200 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
├─sda2 8:2 0 1G 0 part [SWAP]
└─sda3 8:3 0 18.5G 0 part /
sdb 8:16 0 20G 0 disk
[root@hdss7-200 ~]# pvcreate /dev/sdb
Physical volume "/dev/sdb" successfully created.
# 查看pv
[root@hdss7-200 ~]# pvdisplay
"/dev/sdb" is a new physical volume of "20.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb
VG Name
PV Size 20.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID xE8lvt-Rjmi-0PmE-K2O3-epdr-hJEx-XfXzr3
2.第二步：添加VG
[root@hdss7-200 ~]# vgcreate storage /dev/sdb
Volume group "storage" successfully created
# 查看卷组
[root@hdss7-200 ~]# vgdisplay
--- Volume group ---
# 卷组的名字
VG Name storage
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
# 卷组的大小
VG Size <20.00 GiB
PE Size 4.00 MiB
Total PE 5119
Alloc PE / Size 0 / 0
Free PE / Size 5119 / <20.00 GiB
VG UUID PcjNur-WcsZ-dhzj-vmRf-kSQG-51Se-lilfzO
3.第三步：创建LV
# 创建一个逻辑卷名字叫做block1从卷组storage中去分容量。
[root@hdss7-200 ~]# lvcreate -n block1 -L 10G storage
Logical volume "block1" created.
-n # 指定块设备名称
-L # 指定块设备大小
# 查看逻辑卷
[root@hdss7-200 ~]# lvdisplay
--- Logical volume ---
# 卷的位置
LV Path /dev/storage/block1
LV Name block1
VG Name storage
LV UUID UC72Oq-HkYP-Yg6G-PoU6-xGq3-pjjE-Ny6Xx6
LV Write Access read/write
LV Creation host, time hdss7-200.host.com, 2021-05-21 01:51:38 +0800
LV Status available
# open 0
# 卷的大小
LV Size 10.00 GiB
Current LE 2560
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
# 原理
[root@hdss7-200 ~]# ls /dev/storage/block1 -l
lrwxrwxrwx 1 root root 7 May 21 01:51 /dev/storage/block1 -> ../dm-0
4.格式化挂载使用
[root@hdss7-200 ~]# mkfs.ext4 /dev/storage/block1
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
655360 inodes, 2621440 blocks
131072 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2151677952
80 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
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
[root@hdss7-200 ~]# mount /dev/storage/block1 /mnt/
[root@hdss7-200 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
├─sda2 8:2 0 1G 0 part [SWAP]
└─sda3 8:3 0 18.5G 0 part /
# 可以看到大小有20G只分了10G
sdb 8:16 0 20G 0 disk
└─storage-block1 253:0 0 10G 0 lvm /mnt
五、扩容逻辑卷
1.在已有的卷组中还有剩余容量
如果说现在的block1 卷容量快满了，要进行扩容，首先查看VG的信息，看看vg中有没有剩余的空间，如果有就可以直接扩容如果没有就需要添加新的物理磁盘了。
[root@hdss7-200 ~]# vgdisplay
--- Volume group ---
VG Name storage
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 1
Act PV 1
# 本来是20G,但是实际容量是<20G的
VG Size <20.00 GiB
PE Size 4.00 MiB
Total PE 5119
Alloc PE / Size 2560 / 10.00 GiB
# 可用的<10G,创建block1的时候使用过10G
Free PE / Size 2559 / <10.00 GiB
VG UUID PcjNur-WcsZ-dhzj-vmRf-kSQG-51Se-lilfzO
扩容逻辑卷block1 就是扩容LV
# 把逻辑卷block1扩容到11G
[root@hdss7-200 ~]# lvextend -L 11G /dev/storage/block1
Size of logical volume storage/block1 changed from 10.00 GiB (2560 extents) to 11.00 GiB (2816 extents).
Logical volume storage/block1 successfully resized.
# 或者使用,这种方法在原有的基础上加2G，是在storage VG当中去自动的分取容量。
[root@hdss7-200 ~]# lvextend -L +2G /dev/storage/block1
Size of logical volume storage/block1 changed from 11.00 GiB (2816 extents) to 13.00 GiB (3328 extents).
Logical volume storage/block1 successfully resized.
查看容量
# 可以看到现在的容量是13G
[root@hdss7-200 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
├─sda2 8:2 0 1G 0 part [SWAP]
└─sda3 8:3 0 18.5G 0 part /
sdb 8:16 0 20G 0 disk
└─storage-block1 253:0 0 13G 0 lvm /mnt
sr0 11:0 1 1024M 0 rom
# 但是在挂载中
[root@hdss7-200 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
*******************
# 只有9.8G
/dev/mapper/storage-block1 9.8G 37M 9.2G 1% /mnt
同步更改的容量信息
# 如果是xfs的文件系统
[root@hdss7-200 ~]# xfs_growfs /dev/storage/block1
# 如果是ext4文件系统，先检查文件系统完整性
[root@hdss7-200 ~]# e2fsck -f /dev/storage/block1
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/storage/block1: 11/655360 files (0.0% non-contiguous), 83137/2621440 blocks
# 再更改扩容的容量
[root@hdss7-200 ~]# resize2fs /dev/storage/block1
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/storage/block1 to 3407872 (4k) blocks.
The filesystem on /dev/storage/block1 is now 3407872 blocks long.
[root@hdss7-200 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
*******************
/dev/mapper/storage-block1 13G 41M 12G 1% /mnt
2.新加磁盘或分区的扩容
扩容逻辑卷首先要知道该逻辑卷是用的哪个卷组中的容量。比如扩容根分区。扩容的步骤都差不多
- 初始化PV
- 扩展VG
- 扩展逻辑卷
- 更新磁盘容量
直接扩容/分区，这种就是经常要扩容的方式，显示的信息是在centos的VG中有一个root的逻辑卷，挂载到了根目录。
一般思路就是先扩展VG centos
再扩展逻辑卷LV root
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 19G 0 part
├─centos-root 253:0 0 17G 0 lvm /
└─centos-swap 253:1 0 2G 0 lvm [SWAP]me
# 现在的/目录挂载的容量只有17G
查看现在有的VG
[root@localhost ~]# vgdisplay
--- Volume group ---
# VG的名字叫做centos,要对它进行扩容。
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
# 看得出这个VG已经被使用完了
VG Size <19.00 GiB
PE Size 4.00 MiB
Total PE 4863
Alloc PE / Size 4863 / <19.00 GiB
Free PE / Size 0 / 0
VG UUID X32zoj-u7lp-f8TX-0DGK-CZyv-CX1p-vN3qPd
扩容VG
# 先初始化一个PV,一个分区或者是一个磁盘
[root@localhost ~]# pvcreate /dev/sdb
Physical volume "/dev/sdb" successfully created.
# 扩展VG
[root@localhost ~]# vgextend centos /dev/sdb
Volume group "centos" successfully extended
# 查看信息
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
# 现在已经扩容成功，差不多大了2倍的样子。这样扩展LV的时候就可以直接，从VG中分区容量。
VG Size 38.99 GiB
PE Size 4.00 MiB
Total PE 9982
Alloc PE / Size 4863 / <19.00 GiB
Free PE / Size 5119 / <20.00 GiB
VG UUID X32zoj-u7lp-f8TX-0DGK-CZyv-CX1p-vN3qPd
扩容逻辑卷
# 扩容至25G
[root@localhost ~]# lvextend -L 25G /dev/centos/root
Size of logical volume centos/root changed from <17.00 GiB (4351 extents) to 25.00 GiB (6400 extents).
Logical volume centos/root successfully resized.
# 或者
# 在现有容量的基础上再增加5G
[root@localhost ~]# lvextend -L +5G /dev/centos/root
Size of logical volume centos/root changed from 25.00 GiB (6400 extents) to 30.00 GiB (7680 extents).
Logical volume centos/root successfully resized.
# 现在有30G了
更新卷大小
[root@localhost ~]# xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=1113856 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=4455424, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 4455424 to 7864320
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 19G 0 part
├─centos-root 253:0 0 30G 0 lvm /
└─centos-swap 253:1 0 2G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk
└─centos-root 253:0 0 30G 0 lvm /
# 现在可以看到根目录有30G了。
六、缩容逻辑卷
在对逻辑卷进行缩容操作时，其丢失数据的风险更大。所以在生产环境中执行相应操作时，一定要提前备份好数据。另外Linux系统规定，在对LVM逻辑卷进行缩容操作之前，对于ext文件系统要先检查文件系统的完整性（当然这也是为了保证数据安全）。在执行缩容操作前记得先把文件系统卸载掉。
[root@localhost ~]# lvreduce -L 20G /dev/centos/root
WARNING: Reducing active and open logical volume to 20.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce centos/root? [y/n]: y
Size of logical volume centos/root changed from 30.00 GiB (7680 extents) to 20.00 GiB (5120 extents).
Logical volume centos/root successfully resized.
# 或者
lvreduce -L -8G /dev/mapper/centos-home
xfs 文件系统只支持增大分区空间的情况，不支持减小的情况。
# 最后使用即可
e2fsck -f /dev/centos/root