LVM 逻辑卷管理器¶
LVM(Logical Volume Manager)逻辑卷管理是在Linux 2.4 内核以上实现的磁盘管理技术。它是 Linux 环境下对磁盘分区进行管理的一种机制。
当遇到某个分区空间耗尽时，解决的方法通常是使用符号链接，或者使用调整分区大小的工具，但这只是暂时解决办法，没有从根本上解决问题。随着Linux 的逻辑卷管理功能的出现，这些问题都迎刃而解，用户在无需停机的情况下可以方便地调整各个分区大小。
LVM 技术是在硬盘分区和文件系统之间添加了一个逻辑层，它提供了一个抽象的卷组，可以把多块硬盘进行卷组合并。用户不必关心物理硬盘设备的底层架构和布局，可以实现对硬盘分区的动态调整。
- 命令
| 功能 | 物理卷 PV | 卷组 VG | 逻辑卷 LV |
|---|---|---|---|
| 扫描 | pvscan | vgscan | lvscan |
| 创建 | pvcreate | vgcreate | lvcreate |
| 查看 | pvdisplay | vgdisplay | lvdisplay |
| 删除 | pvremove | vgremove | lvremove |
| 扩展 | vgextend | lvextend | |
| 缩小 | vgreduce | lvreduce |
创建物理卷¶
准备几块磁盘
[root@localhost ~]# ll /dev/sd*
brw-rw----. 1 root disk 8, 0 7月 31 06:52 /dev/sda
brw-rw----. 1 root disk 8, 1 7月 31 06:52 /dev/sda1
brw-rw----. 1 root disk 8, 2 7月 31 06:52 /dev/sda2
brw-rw----. 1 root disk 8, 16 7月 31 07:41 /dev/sdb
brw-rw----. 1 root disk 8, 32 7月 31 07:41 /dev/sdc
让 /dev/sdb、/dev/sdc 支持 LVM
[root@localhost ~]# pvcreate /dev/sdb /dev/sdc
Physical volume "/dev/sdb" successfully created.
Physical volume "/dev/sdc" successfully created.
[root@localhost ~]#
创建卷组¶
创建一个卷组，并把 /dev/sdb、/dev/sdc 加入到卷组
[root@localhost ~]# vgcreate vg1 /dev/sdb /dev/sdc
Volume group "vg1" successfully created
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <9.00g 0
vg1 2 0 0 wz--n- 9.99g 9.99g
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name vg1
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 LESM13-wmSU-sTAN-RFi3-qbsn-WEdg-LSay6x
--- 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 <9.00 GiB
PE Size 4.00 MiB
Total PE 2303
Alloc PE / Size 2303 / <9.00 GiB
Free PE / Size 0 / 0
VG UUID 13hZJW-bqaq-SWSX-dA7U-xjT3-AiBE-4jwgDt
[root@localhost ~]#
- PE 大小调整
PE 默认大小 4m
- 创建卷组时调整默认 PE 大小:
vgcreate -s 16m vg1 /dev/sdb /dev/sdc - vgchange 命令调整:
vgchange vg1 -s 4m
切割逻辑卷¶
在对逻辑卷进行切割时有两种计量单位。
第一种是以容量为单位，所使用的参数为-L。例如，使用-L 150M生成一个大小为150MB的逻辑卷。
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- <8.00g
swap centos -wi-ao---- 1.00g
[root@localhost ~]# lvcreate -n lv1 -L 300m vg1
Logical volume "lv1" created.
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- <8.00g
swap centos -wi-ao---- 1.00g
lv1 vg1 -wi-a----- 300.00m
[root@localhost ~]# lvdisplay vg1/lv1
--- Logical volume ---
LV Path /dev/vg1/lv1
LV Name lv1
VG Name vg1
LV UUID PYFQkX-MBIr-Edd2-aeJu-QSkk-c56U-3NMR1v
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2019-08-01 07:59:01 +0800
LV Status available
# open 0
LV Size 300.00 MiB
Current LE 75
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
[root@localhost ~]#
另外一种是以基本单元的个数为单位，所使用的参数为-l。每个基本单元的大小默认为4MB。例如，使用-l 37可以生成一个大小为37×4MB=148MB的逻辑卷。
[root@localhost ~]# lvcreate -n lv2 -l 37 vg1
Logical volume "lv2" created.
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- <8.00g
swap centos -wi-ao---- 1.00g
lv1 vg1 -wi-a----- 148.00m
lv2 vg1 -wi-a----- 148.00m
[root@localhost ~]# lvdisplay /dev/vg1/lv
/dev/vg1/lv1 /dev/vg1/lv2
[root@localhost ~]# lvdisplay /dev/vg1/lv2
--- Logical volume ---
LV Path /dev/vg1/lv2
LV Name lv2
VG Name vg1
LV UUID QbKDQ8-ieSy-ThbL-Z2YI-K23k-hm77-ZdEaWb
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2019-08-01 07:55:52 +0800
LV Status available
# open 0
LV Size 148.00 MiB
Current LE 37
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:3
[root@localhost ~]#
格式化逻辑卷¶
[root@localhost ~]# mkfs.xfs /dev/vg1/lv1
meta-data=/dev/vg1/lv1 isize=512 agcount=4, agsize=19200 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=76800, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=855, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@localhost ~]# mkdir /test1
[root@localhost ~]# cat <<end>> /etc/fstab
> /dev/vg1/lv1 /test1 xfs defaults 0 0
> end
[root@localhost ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Wed Jun 12 21:56:17 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=b9d39bf8-743f-4a01-b856-33688690ada4 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
/dev/vg1/lv1 /test1 xfs defaults 0 0
[root@localhost ~]# mount -a
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 297M 16M 282M 6% /test1
[root@localhost ~]#
扩容逻辑卷¶
- xfs 格式
[root@localhost ~]# vgdisplay vg1
--- Volume group ---
VG Name vg1
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 6
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
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 75 / 300.00 MiB
Free PE / Size 2483 / <9.70 GiB
VG UUID o1xUxv-U8yj-EDEw-YYz8-PTSl-XfmW-w0CMe5
[root@localhost ~]# lvextend -L 500m /dev/vg1/lv1
Size of logical volume vg1/lv1 changed from 300.00 MiB (75 extents) to 500.00 MiB (125 extents).
Logical volume vg1/lv1 successfully resized.
[root@localhost ~]# xfs_growfs /dev/vg1/lv1
meta-data=/dev/mapper/vg1-lv1 isize=512 agcount=4, agsize=19200 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=76800, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=855, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 76800 to 128000
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
[root@localhost ~]#
- ext* 格式
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- <8.00g
swap centos -wi-ao---- 1.00g
lv1 vg1 -wi-ao---- 500.00m
lv2 vg1 -wi-a----- 148.00m
[root@localhost ~]# mkfs.ext4 /dev/vg1/lv2
mke2fs 1.42.9 (28-Dec-2013)
文件系统标签=
OS type: Linux
块大小=1024 (log=0)
分块大小=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
38000 inodes, 151552 blocks
7577 blocks (5.00%) reserved for the super user
第一个数据块=1
Maximum filesystem blocks=33816576
19 block groups
8192 blocks per group, 8192 fragments per group
2000 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
Allocating group tables: 完成
正在写入inode表: 完成
Creating journal (4096 blocks): 完成
Writing superblocks and filesystem accounting information: 完成
[root@localhost ~]# mkdir /test2
[root@localhost ~]# cat <<end>> /etc/fstab
> /dev/vg1/lv2 /test2 ext4 defaults 0 0
> end
[root@localhost ~]# mount -a
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
/dev/mapper/vg1-lv2 140M 1.6M 128M 2% /test2
[root@localhost ~]# lvextend -L 300m vg1/lv2
Size of logical volume vg1/lv2 changed from 148.00 MiB (37 extents) to 300.00 MiB (75 extents).
Logical volume vg1/lv2 successfully resized.
[root@localhost ~]# resize2fs /dev/vg1/lv2
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/vg1/lv2 is mounted on /test2; on-line resizing required
old_desc_blocks = 2, new_desc_blocks = 3
The filesystem on /dev/vg1/lv2 is now 307200 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 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
/dev/mapper/vg1-lv2 287M 2.1M 269M 1% /test2
[root@localhost ~]#
缩容逻辑卷¶
缩容操作前记得先备份好数据，并卸载挂载点。
xfs 格式 不支持缩容。
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
/dev/mapper/vg1-lv2 287M 2.1M 269M 1% /test2
[root@localhost ~]# resize2fs /dev/vg1/lv2 100m
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/vg1/lv2 is mounted on /test2; on-line resizing required
resize2fs: On-line shrinking not supported
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
/dev/mapper/vg1-lv2 287M 2.1M 269M 1% /test2
[root@localhost ~]# umount /test2/
[root@localhost ~]# resize2fs /dev/vg1/lv2 100m
resize2fs 1.42.9 (28-Dec-2013)
请先运行 'e2fsck -f /dev/vg1/lv2'.
[root@localhost ~]# e2fsck -f .
./ ../ .bash_history .bash_logout .bash_profile .bashrc .cshrc .pki/ .ssh/ .tcshrc .viminfo
[root@localhost ~]# e2fsck -f /dev/vg1/lv2
e2fsck 1.42.9 (28-Dec-2013)
第一步: 检查inode,块,和大小
第二步: 检查目录结构
第3步: 检查目录连接性
Pass 4: Checking reference counts
第5步: 检查簇概要信息
/dev/vg1/lv2: 11/76000 files (0.0% non-contiguous), 15759/307200 blocks
[root@localhost ~]# resize2fs /dev/vg1/lv2 100m
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg1/lv2 to 102400 (1k) blocks.
The filesystem on /dev/vg1/lv2 is now 102400 blocks long.
[root@localhost ~]# mount -a
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
/dev/mapper/vg1-lv2 93M 1.6M 85M 2% /test2
[root@localhost ~]#
逻辑卷快照¶
LVM还具备有“快照卷”功能，该功能类似于虚拟机软件的还原时间点功能。
快照卷的容量必须等同于逻辑卷的容量；
所在卷组有足够容量；
快照卷仅一次有效，一旦执行还原操作后则会被立即自动删除。
- 创建快照
[root@localhost ~]# vgdisplay vg1
--- Volume group ---
VG Name vg1
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 9
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 9.99 GiB
PE Size 4.00 MiB
Total PE 2558
Alloc PE / Size 200 / 800.00 MiB
Free PE / Size 2358 / 9.21 GiB
VG UUID o1xUxv-U8yj-EDEw-YYz8-PTSl-XfmW-w0CMe5
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 8.0G 2.0G 6.1G 24% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.5M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 194M 821M 20% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 497M 16M 482M 4% /test1
/dev/mapper/vg1-lv2 93M 1.6M 85M 2% /test2
[root@localhost ~]# ll /test1
总用量 0
[root@localhost ~]# cat <<end> /test1/hello.txt
> hello test1
> ssssssssss
> ssssssssss
> ssssssssss
> hello test1
> end
[root@localhost ~]# ll /test1/
总用量 4
-rw-r--r--. 1 root root 57 8月 1 08:35 hello.txt
[root@localhost ~]# lvdisplay /dev/vg1/lv1
--- Logical volume ---
LV Path /dev/vg1/lv1
LV Name lv1
VG Name vg1
LV UUID PYFQkX-MBIr-Edd2-aeJu-QSkk-c56U-3NMR1v
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2019-08-01 07:59:01 +0800
LV Status available
# open 1
LV Size 500.00 MiB
Current LE 125
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
[root@localhost ~]# lvcreate -L 500m -s -n backup-lv1 /dev/vg1/lv1
Logical volume "backup-lv1" created.
[root@localhost ~]# lvdisplay /dev/vg1/lv1
--- Logical volume ---
LV Path /dev/vg1/lv1
LV Name lv1
VG Name vg1
LV UUID PYFQkX-MBIr-Edd2-aeJu-QSkk-c56U-3NMR1v
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2019-08-01 07:59:01 +0800
LV snapshot status source of
backup-lv1 [active]
LV Status available
# open 1
LV Size 500.00 MiB
Current LE 125
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
[root@localhost ~]#
可以看到多了一组 LV snapshot status 信息。
在逻辑卷所挂载的目录中创建一个100MB的文件用于测试
[root@localhost ~]# dd if=/dev/zero of=/test1/file count=1 bs=100M
记录了1+0 的读入
记录了1+0 的写出
104857600字节(105 MB)已复制，0.0740664 秒，1.4 GB/秒
[root@localhost ~]# ll -h /test1
总用量 101M
-rw-r--r--. 1 root root 100M 8月 1 08:49 file
-rw-r--r--. 1 root root 57 8月 1 08:35 hello.txt
[root@localhost ~]#
- 快照回退
快照卷会被自动删除掉，并且刚刚在逻辑卷设备被执行快照操作后再创建出来的100MB的垃圾文件也被清除了。
[root@localhost ~]# lvconvert --merge /dev/vg1/backup-lv1
Merging of volume vg1/backup-lv1 started.
vg1/lv1: Merged: 4.43%
vg1/lv1: Merged: 100.00%
[root@localhost ~]# ll /test1/
总用量 4
-rw-r--r--. 1 root root 57 8月 1 08:35 hello.txt
[root@localhost ~]#
删除逻辑卷¶
取消逻辑卷与目录的挂载关联，删除配置文件中永久生效的设备参数。
- 删除逻辑卷
[root@localhost ~]# umount /test1
[root@localhost ~]# lvremove /dev/vg1/lv1 -f
Logical volume "lv1" successfully removed
[root@localhost ~]#
- 删除卷组
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <9.00g 0
vg1 2 0 0 wz--n- 9.99g 9.99g
[root@localhost ~]# vgremove vg1 -f
Volume group "vg1" successfully removed
- 删除物理卷
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <9.00g 0
/dev/sdb lvm2 --- 5.00g 5.00g
/dev/sdc lvm2 --- 5.00g 5.00g
[root@localhost ~]# pvremove /dev/sdb /dev/sdc
Labels on physical volume "/dev/sdb" successfully wiped.
Labels on physical volume "/dev/sdc" successfully wiped.
[root@localhost ~]#
最后更新: March 18, 2024