使用Linux好久了，一定会意识到一个问题，某个分区容量不够用了，想要扩容怎么办？这里就涉及到LVM逻辑卷的管理了，可以动态调整Linux分区容量。

LVM 概述#

全称Logical Volume Manager，可以动态调整磁盘容量，提高磁盘管理灵活性。

在安装LVM的方案安装的系统。

但是/boot分区必须独立出来，不能基于LVM创建。

PV 物理卷#

物理卷，Physical Volume，是LVM机制的基本存储设备，通常对应一个普通分区或是整个硬盘。

创建物理卷时，会在分区或磁盘头部创建一个用于记录LVM属性的保留区块，并把存储空间分割成默认大小为4MB的基本单元(Physical Extend，PE)，从而构成物理卷。

普通分区先转换分区类型为8e；整块硬盘，可以将所有的空间划分为一个主分区再做调整。

VG 卷组#

卷组，Volume Group，是由一个或多个物理卷组成的一个整体。可以动态添加、移除物理卷，创建时可以指定PE大小。

LV 逻辑卷#

逻辑卷，Logical Volume，建立在卷组之上，与物理卷没有直接关系。格式化后，即可挂载使用。

三者关系#

通过以上对三者的解释可以看出，建立LVM的过程。首先，将普通分区或整个硬盘创建为物理卷；然后，将一个或多个物理卷创建为卷组；最后，在卷组上分割不同的数据存储空间形成逻辑卷。有了逻辑卷，就可以格式化、挂载使用了。

LVM 管理#

LVM 常用命令#

功能PV 管理命令VG 管理命令LV 管理命令

Scan(扫描)

pvscan

vgscan

lvscan

Create(建立)

pvcreate

vgcreate

lvcreate

Display(显示)

pvdisplay

vgdisplay

lvdisplay

Remove(移除)

pvremove

vgremove

lvremove

Extend(扩展)

/

vgextend

lvextend

Reduce(减少)

/

vgreduce

lvreduce

PV 管理#

pvsacn#

扫描列出系统中所有的物理卷

-e:仅显示属于输出卷组的物理卷

-n：仅显示不属于任何卷组的物理卷

[root@localhost ~]# pvscan

PV /dev/sda2 VG centos lvm2 [<19.00 GiB / 0 free]

PV /dev/sdb1 lvm2 [<20.00 GiB]

PV /dev/sdc1 lvm2 [<20.00 GiB]

Total: 3 [58.99 GiB] / in use: 1 [<19.00 GiB] / in no VG: 2 [<40.00 GiB]

pvcreate#

将分区或整个硬盘转换成物理卷

[root@localhost ~]# pvcreate /dev/sd{b,c}1

Physical volume "/dev/sdb1" successfully created.

Physical volume "/dev/sdc1" successfully created.

pvdisplay#

显示物理卷的详细信息

[root@localhost ~]# pvdisplay

--- Physical volume ---

PV Name /dev/sda2

VG Name centos

PV Size <19.00 GiB / not usable 3.00 MiB

Allocatable yes (but full)

PE Size 4.00 MiB

Total PE 4863

Free PE 0

Allocated PE 4863

PV UUID E4eovQ-CgPo-OSDK-75MO-BfD8-pGsP-BUlqip

"/dev/sdb1" is a new physical volume of "<20.00 GiB"

--- NEW Physical volume ---

PV Name /dev/sdb1

VG Name

PV Size <20.00 GiB

Allocatable NO

PE Size 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID gR5mm3-f50o-XLTq-34GY-n6Iz-WXkQ-uMZAkJ

"/dev/sdc1" is a new physical volume of "<20.00 GiB"

--- NEW Physical volume ---

PV Name /dev/sdc1

VG Name

PV Size <20.00 GiB

Allocatable NO

PE Size 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID O2gKxa-ONts-kyXK-zZrO-3dDg-FhtI-V6GPy9

pvremove#

删除指定的物理卷，还原成普通分区或磁盘

TIPS：只有不属于卷组的物理卷才可以删除还原。

[root@localhost ~]# pvremove /dev/sdd1

Labels on physical volume "/dev/sdd1" successfully wiped.

VG 管理#

vgscan#

扫描系统中已建立的LVM卷组

[root@localhost ~]# vgscan

Reading volume groups from cache.

Found volume group "class" using metadata type lvm2

Found volume group "centos" using metadata type lvm2

vgcreate#

将一个或多个物理卷创建为一个卷组

-l：卷组上允许创建的最大逻辑卷数

-p：卷组中允许添加的最大物理卷数

-s：卷组上的物理卷的PE大小

[root@localhost ~]# vgcreate class /dev/sd{b,c}1

Volume group "class" successfully created

vgdisplay#

显示系统中各卷组的详细信息

[root@localhost ~]# vgdisplay

--- Volume group ---

VG Name class

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 39.99 GiB

PE Size 4.00 MiB

Total PE 10238

Alloc PE / Size 0 / 0

Free PE / Size 10238 / 39.99 GiB

VG UUID ZtQvGX-YOdy-U8wj-mGQs-TT1e-1PBR-dBNKAG

--- 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 <19.00 GiB

PE Size 4.00 MiB

Total PE 4863

Alloc PE / Size 4863 / <19.00 GiB

Free PE / Size 0 / 0

VG UUID bLPJGb-SQQ3-KcUb-OSdo-qaMR-9hJE-MTkc7a

vgremove#

删除指定的卷组

TIPS：卷组下面的逻辑卷没有被挂载使用，卷组删除时会一并删除下面的逻辑卷。

[root@localhost ~]# vgremove class

Volume group "class" successfully removed

vgextend#

添加新的物理卷，动态扩展卷组的磁盘空间

[root@localhost ~]# vgextend class /dev/sdd1

Volume group "class" successfully extended

vgreduce#

删除卷组中的物理卷，减少卷组容量，

-a：如果命令行中没有指定要删除的物理卷，则删除所有的空物理卷。(all)

TIPS：删除啊前确保对应的物理卷没有在使用，就是下面没有逻辑卷，否则删除不了。

[root@localhost ~]# vgreduce class /dev/sdd1

Removed "/dev/sdd1" from volume group "class"

[root@localhost ~]# vgreduce -a class

Physical volume "/dev/sdb1" still in use

Physical volume "/dev/sdc1" still in use

Removed "/dev/sdd1" from volume group "class"

LV 管理#

lvscan#

扫描系统中已建立的LVM逻辑卷

[root@localhost ~]# lvscan

ACTIVE '/dev/class/stu01' [25.00 GiB] inherit

ACTIVE '/dev/class/stu02' [14.99 GiB] inherit

ACTIVE '/dev/centos/swap' [2.00 GiB] inherit

ACTIVE '/dev/centos/root' [<17.00 GiB] inherit

lvcreate#

从指定的卷组中分割空间，创建新的逻辑卷

-L：指定逻辑卷的大小，单位为KMGT

-l：指定百分比创建，如50%vg卷组的一半空间、100%free所有剩下的。

-n：指定逻辑卷的名称

[root@localhost ~]# lvcreate -L 15G -n stu01 class

Logical volume "stu01" created.

[root@localhost ~]# lvcreate -l 100%free -n stu02 class

Logical volume "stu02" created.

lvdisplay#

显示逻辑卷的详细信息

[root@localhost ~]# lvdisplay

--- Logical volume ---

LV Path /dev/class/stu01

LV Name stu01

VG Name class

LV UUID XUP7dq-IM9f-PdKk-XpDH-J1hx-kkuB-cOu3Qx

LV Write Access read/write

LV Creation host, time localhost.localdomain, 2019-08-24 09:42:35 +0800

LV Status available

# open 0

LV Size 25.00 GiB

Current LE 6400

Segments 2

Allocation inherit

Read ahead sectors auto

- currently set to 8192

Block device 253:2

--- Logical volume ---

LV Path /dev/class/stu02

LV Name stu02

VG Name class

LV UUID P7iMC1-X0oT-6TCH-vLYj-HW2j-6QMu-rS7Jyp

LV Write Access read/write

LV Creation host, time localhost.localdomain, 2019-08-24 09:59:30 +0800

LV Status available

# open 0

LV Size 14.99 GiB

Current LE 3838

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 8192

Block device 253:3

--- Logical volume ---

LV Path /dev/centos/swap

LV Name swap

VG Name centos

LV UUID NXiaXT-T6yv-ktM2-plyS-j6Hg-hkvu-1JQ2eL

LV Write Access read/write

LV Creation host, time localhost, 2019-08-16 17:12:19 +0800

LV Status available

# open 2

LV Size 2.00 GiB

Current LE 512

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 8192

Block device 253:1

--- Logical volume ---

LV Path /dev/centos/root

LV Name root

VG Name centos

LV UUID 7FnsfT-B8xi-3vgu-8N0k-nzNn-8Rra-eoE4iC

LV Write Access read/write

LV Creation host, time localhost, 2019-08-16 17:12:19 +0800

LV Status available

# open 1

LV Size <17.00 GiB

Current LE 4351

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 8192

Block device 253:0

lvremove#

删除指定的逻辑卷

TIPS：备份数据，解挂载，删除。

[root@localhost ~]# umount /mnt/stu02/

[root@localhost ~]# lvremove /dev/class/stu02

lvextend#

动态扩展LVM逻辑卷的空间大小

-L：指定扩展逻辑卷的大小，单位为KMGT

-l：指定百分比扩建，如100%free所有剩下的。

[root@localhost ~]# lvextend -L +8G /dev/class/stu01

[root@localhost ~]# lvextend -L +8G /dev/class/stu02

TIPS：已挂载，使用在线调整大小，xfs使用xfs_growfs，ext4使用resize2fs。

[root@localhost ~]# xfs_growfs /dev/class/stu01

[root@localhost ~]# resize2fs /dev/class/stu02

lvreduce#

减少LVM逻辑卷的空间大小，

-L：指定逻辑卷的大小，单位为KMGT

TIPS：对于xfs文件系统，备份数据，解挂载，减少空间，强制格式化，重新挂载。需要注意xfs文件系统只能扩大，不能缩小，非要缩小的话，只有缩小后并强制格式化，但这么做数据就丢失了。

[root@localhost ~]# umount /mnt/stu01/

[root@localhost ~]# lvreduce -L -10G /dev/class/stu01

[root@localhost ~]# mkfs.xfs -f /dev/class/stu01

[root@localhost ~]# mount -a

[root@localhost ~]# df -hT

TIPS：对于ext4这类文件系统，备份数据，解挂载，e2fsck -f检查文件系统完整性，resize2fs设置文件系统大小，lvreduce设置逻辑卷大小，重新挂载。

[root@localhost ~]# umount /mnt/stu02/

[root@localhost ~]# e2fsck -f /dev/class/stu02

[root@localhost ~]# resize2fs /dev/class/stu02 10G

[root@localhost ~]# lvreduce -L 10G /dev/class/stu02

[root@localhost ~]# mount -a

[root@localhost ~]# df -hT

LVM 实验#

创建 LVM 逻辑卷#

1.添加两块20G的磁盘，重启机器，并对其进行分区，全部空间分为一个主分区，类型改为Linux LVM，ID为8e。分区过程省略，不清楚可参考上一篇博客。

[root@localhost ~]# fdisk -l /dev/sd{b,c} | grep -i "linux lvm"

/dev/sdb1 2048 41943039 20970496 8e Linux LVM

/dev/sdc1 2048 41943039 20970496 8e Linux LVM

2.将/dev/sdb1、/dev/sdc1转换为物理卷。

[root@localhost ~]# pvcreate /dev/sd{b,c}1

Physical volume "/dev/sdb1" successfully created.

Physical volume "/dev/sdc1" successfully created.

3.创建名称为class的卷组，并将sdb1和sdc1添加进卷组。

[root@localhost ~]# vgcreate class /dev/sd{b,c}1

Volume group "class" successfully created

4.划分大小为15G，名称为stu01的逻辑卷，然后再扩容10G；剩下的空间创建名称为stu02的逻辑卷。

[root@localhost ~]# lvcreate -L 15G -n stu01 class

Logical volume "stu01" created.

[root@localhost ~]# lvextend -L +10G /dev/class/stu01

Size of logical volume class/stu01 changed from 15.00 GiB (3840 extents) to 25.00 GiB (6400 extents).

Logical volume class/stu01 successfully resized.

[root@localhost ~]# lvcreate -l 100%free -n stu02 class

Logical volume "stu02" created.

5.格式化逻辑卷，stu01为xfs，stu02为ext4，设置自动挂载，挂载后就可以使用了。

[root@localhost ~]# mkfs.xfs /dev/class/stu01

meta-data=/dev/class/stu01 isize=512 agcount=4, agsize=1638400 blks

= sectsz=512 attr=2, projid32bit=1

= crc=1 finobt=0, sparse=0

data = bsize=4096 blocks=6553600, imaxpct=25

= sunit=0 swidth=0 blks

naming =version 2 bsize=4096 ascii-ci=0 ftype=1

log =internal log bsize=4096 blocks=3200, version=2

= sectsz=512 sunit=0 blks, lazy-count=1

realtime =none extsz=4096 blocks=0, rtextents=0

[root@localhost ~]# mkfs.ext4 /dev/class/stu02

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

983040 inodes, 3930112 blocks

196505 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=2151677952

120 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

Allocating group tables: done

Writing inode tables: done

Creating journal (32768 blocks): done

Writing superblocks and filesystem accounting information: done

[root@localhost ~]# mkdir /mnt/stu0{1,2}

[root@localhost ~]# vim /etc/fstab

//最后面添加下面两行内容

/dev/class/stu01 /mnt/stu01 xfs defaults 0 0

/dev/class/stu02 /mnt/stu02 ext4 defaults 0 0

[root@localhost ~]# mount -a

[root@localhost ~]# df -hT

Filesystem Type Size Used Avail Use% Mounted on

/dev/mapper/centos-root xfs 17G 927M 17G 6% /

devtmpfs devtmpfs 901M 0 901M 0% /dev

tmpfs tmpfs 912M 0 912M 0% /dev/shm

tmpfs tmpfs 912M 8.7M 904M 1% /run

tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup

/dev/sda1 xfs 1014M 143M 872M 15% /boot

tmpfs tmpfs 183M 0 183M 0% /run/user/0

/dev/mapper/class-stu01 xfs 25G 33M 25G 1% /mnt/stu01

/dev/mapper/class-stu02 ext4 15G 41M 14G 1% /mnt/stu02

扩容 LVM 逻辑卷#

1.再添加一块20G的磁盘，重启机器，并对其进行分区，全部空间分为一个主分区，类型改为Linux LVM，ID为8e。

[root@localhost ~]# fdisk -l /dev/sd{b..d} | grep -i "linux lvm"

/dev/sdb1 2048 41943039 20970496 8e Linux LVM

/dev/sdc1 2048 41943039 20970496 8e Linux LVM

/dev/sdd1 2048 41943039 20970496 8e Linux LVM

2.将/dev/sdd1转换为物理卷。

[root@localhost ~]# pvcreate /dev/sdd1

Physical volume "/dev/sdd1" successfully created.

3.若是卷组剩余空间不够，就要先对class卷组进行扩容。

[root@localhost ~]# vgdisplay class

--- Volume group ---

VG Name class

System ID

Format lvm2

Metadata Areas 2

Metadata Sequence No 6

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

VG Size 39.99 GiB

PE Size 4.00 MiB

Total PE 10238

Alloc PE / Size 10238 / 39.99 GiB

Free PE / Size 0 / 0

VG UUID iB1h9h-2uQa-rD7o-GBVK-pOCA-ek2c-TXieLr

[root@localhost ~]# vgextend class /dev/sdd1

Volume group "class" successfully extended

[root@localhost ~]# vgdisplay class

--- Volume group ---

VG Name class

System ID

Format lvm2

Metadata Areas 3

Metadata Sequence No 7

VG Access read/write

VG Status resizable

MAX LV 0

Cur LV 2

Open LV 2

Max PV 0

Cur PV 3

Act PV 3

VG Size <59.99 GiB

PE Size 4.00 MiB

Total PE 15357

Alloc PE / Size 10238 / 39.99 GiB

Free PE / Size 5119 / <20.00 GiB

VG UUID iB1h9h-2uQa-rD7o-GBVK-pOCA-ek2c-TXieLr

4.对stu01和stu02都扩容8G，分别使用xfs_growfs和resize2fs在线调整大小。

[root@localhost ~]# lvextend -L +8G /dev/class/stu01

Size of logical volume class/stu01 changed from 25.00 GiB (6400 extents) to 33.00 GiB (8448 extents).

Logical volume class/stu01 successfully resized.

[root@localhost ~]# lvextend -L +8G /dev/class/stu02

Size of logical volume class/stu02 changed from 14.99 GiB (3838 extents) to 22.99 GiB (5886 extents).

Logical volume class/stu02 successfully resized.

[root@localhost ~]# xfs_growfs /dev/class/stu01

meta-data=/dev/mapper/class-stu01 isize=512 agcount=4, agsize=1638400 blks

= sectsz=512 attr=2, projid32bit=1

= crc=1 finobt=0 spinodes=0

data = bsize=4096 blocks=6553600, imaxpct=25

= sunit=0 swidth=0 blks

naming =version 2 bsize=4096 ascii-ci=0 ftype=1

log =internal bsize=4096 blocks=3200, version=2

= sectsz=512 sunit=0 blks, lazy-count=1

realtime =none extsz=4096 blocks=0, rtextents=0

data blocks changed from 6553600 to 8650752

[root@localhost ~]# resize2fs /dev/class/stu02

resize2fs 1.42.9 (28-Dec-2013)

Filesystem at /dev/class/stu02 is mounted on /mnt/stu02; on-line resizing required

old_desc_blocks = 2, new_desc_blocks = 3

The filesystem on /dev/class/stu02 is now 6027264 blocks long.

[root@localhost ~]# df -hT

Filesystem Type Size Used Avail Use% Mounted on

/dev/mapper/centos-root xfs 17G 927M 17G 6% /

devtmpfs devtmpfs 901M 0 901M 0% /dev

tmpfs tmpfs 912M 0 912M 0% /dev/shm

tmpfs tmpfs 912M 8.7M 903M 1% /run

tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup

/dev/sda1 xfs 1014M 143M 872M 15% /boot

/dev/mapper/class-stu01 xfs 33G 33M 33G 1% /mnt/stu01

/dev/mapper/class-stu02 ext4 23G 44M 22G 1% /mnt/stu02

tmpfs tmpfs 183M 0 183M 0% /run/user/0

收缩 LVM 逻辑卷#

关于收缩 LVM 逻辑卷，可以参考上面的命令lvreduce。这会涉及到数据安全性问题，谨慎使用。

总结#

内容不多，但是还要实际操作才能了解。就是三步走，创建物理卷，创建卷组，创建逻辑卷，然后格式化并挂载使用。扩容的话，没有挂载使用，就正常扩，然后格式化挂载，已经挂载使用了，扩容后在线调整生效。还有下一篇关于磁盘配额。