LVM逻辑卷管理--在线扩容、逻辑卷与卷组容量缩减、逻辑卷快照
LVM逻辑卷管理
公司生产环境中使用了LVM逻辑卷管理，所以今天花时间整理一下。
通过LVM技术整合所有的磁盘资源进行分区，然后创建PV物理卷形成一个资源池，再划分卷组，最后在卷组上创建不同的逻辑卷，继而初始化逻辑卷，挂载到系统中使用。
LVM对比传统硬盘存储的优点
1、 统一管理：整合多个磁盘或分区形成一个资源池
2、 灵活性：可以使用不同磁盘、不同分区来组成一个逻辑卷
3、 可伸缩性：逻辑卷和卷组的容量都可以使用命令来扩展或者缩减，且不会影响破坏原有数据，支持磁盘热插拔。
4、 支持热插拔
5、 支持在线数据移动
6、 设备命名方便
7、 镜像卷：可以很方便的做数据镜像
8、 卷快照：把逻辑卷中的数据快照保存到新的逻辑卷进行备份
逻辑分区与逻辑卷的区别
逻辑卷与逻辑分区不是同一概念，逻辑分区容量大小不能改变；逻辑卷容量大小可以改变（基于物理卷和卷组之上的逻辑卷）；逻辑卷管理器（LVM）可以更轻松的管理磁盘空间（整合的磁盘池）
LVM原理图
Physical volume (PV物理卷)、Volume group (VG卷组)、Logical volume(LV逻辑卷)，通过图解更容易读懂物理磁盘、磁盘分区、物理卷、卷组、逻辑卷之间的关系（个人理解，仅供参考）
测试环境
内核
LVM1版本需要2.4（包括）以后的内核支持；LVM2需要2.6（包括）以后的内核版本支持。
[root@localhost ~]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
[root@localhost ~]# uname -r
3.10.0-693.el7.x86_64新添加两块磁盘
[root@localhost ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0000457f
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 41943039 19921920 8e Linux LVM
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-root: 18.2 GB, 18249416704 bytes, 35643392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes磁盘分区
第一块磁盘
[root@localhost ~]# fdisk /dev/sdb
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +10G
Partition 1 of type Linux and of size 10 GiB is set
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p #主分区
Partition number (2-4, default 2):
First sector (20973568-41943039, default 20973568):
Using default value 20973568
Last sector, +sectors or +size{K,M,G} (20973568-41943039, default 41943039):
Using default value 41943039
Partition 2 of type Linux and of size 10 GiB is set
Command (m for help): p #第一块磁盘划分两个主分区
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xfba75d9e
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20973567 10485760 83 Linux
/dev/sdb2 20973568 41943039 10484736 83 Linux
Command (m for help): t #做LVM管理，需要修改分区类型为Linux LVM
Partition number (1,2, default 2): 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): t
Partition number (1,2, default 2): 2
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: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xfba75d9e
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20973567 10485760 8e Linux LVM
/dev/sdb2 20973568 41943039 10484736 8e Linux LVM
Command (m for help): w #保存分区信息
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
告诉内核
[root@localhost ~]# partprobe /dev/sdb #更新内核分区表
[root@localhost ~]# ls -l /dev/sdb*
brw-rw----. 1 root disk 8, 16 Oct 13 11:30 /dev/sdb
brw-rw----. 1 root disk 8, 17 Oct 13 11:30 /dev/sdb1
brw-rw----. 1 root disk 8, 18 Oct 13 11:30 /dev/sdb2
[root@localhost ~]#第二块磁盘
创建一个主分区和一个逻辑分区，用来测试扩展分区和逻辑分区是否能够创建PV物理卷并加入VG卷组，实验证明，扩展分区是无法创建PV和加入VG，主分区和逻辑分区可以。
[root@localhost ~]# fdisk /dev/sdc
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.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x5d61bb7c.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p #主分区
Partition number (1-4, default 1):
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +10G
Partition 1 of type Linux and of size 10 GiB is set
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): e #扩展分区，要创建扩展分区之后，才能创建逻辑分区；扩展分区只能创建一个，分区表支持创建最多四分主分区，如果想要创建4个以上的分区，必须创建扩展分区，然后创建逻辑分区
Partition number (2-4, default 2):
First sector (20973568-41943039, default 20973568):
Using default value 20973568
Last sector, +sectors or +size{K,M,G} (20973568-41943039, default 41943039):
Using default value 41943039
Partition 2 of type Extended and of size 10 GiB is set
Command (m for help): n
Partition type:
p primary (1 primary, 1 extended, 2 free)
l logical (numbered from 5)
Select (default p): l #创建逻辑分区
Adding logical partition 5
First sector (20975616-41943039, default 20975616):
Using default value 20975616
Last sector, +sectors or +size{K,M,G} (20975616-41943039, default 41943039):
Using default value 41943039
Partition 5 of type Linux and of size 10 GiB is set
Command (m for help): p
Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x5d61bb7c
Device Boot Start End Blocks Id System
/dev/sdc1 2048 20973567 10485760 83 Linux
/dev/sdc2 20973568 41943039 10484736 5 Extended
/dev/sdc5 20975616 41943039 10483712 83 Linux
Command (m for help): t #修改分区类型
Partition number (1,2,5, default 5): 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): t
Partition number (1,2,5, default 5): 2
Hex code (type L to list all codes): 8e
You cannot change a partition into an extended one or vice versa.
Delete it first.
Type of partition 2 is unchanged: Extended
Command (m for help): t
Partition number (1,2,5, default 5): 5
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x5d61bb7c
Device Boot Start End Blocks Id System
/dev/sdc1 2048 20973567 10485760 8e Linux LVM
/dev/sdc2 20973568 41943039 10484736 5 Extended
/dev/sdc5 20975616 41943039 10483712 8e Linux LVM
Command (m for help): w #保存分区表信息
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# partprobe /dev/sdc
[root@localhost ~]# ls -l /dev/sdc*
brw-rw----. 1 root disk 8, 32 Oct 13 11:35 /dev/sdc
brw-rw----. 1 root disk 8, 33 Oct 13 11:35 /dev/sdc1
brw-rw----. 1 root disk 8, 34 Oct 13 11:35 /dev/sdc2
brw-rw----. 1 root disk 8, 37 Oct 13 11:35 /dev/sdc5创建PV、VG、LV
创建PV物理卷
[root@localhost ~]# pvcreate /dev/sdc2 #sdc2是扩展分区，无法做成物理卷PV
Device /dev/sdc2 not found (or ignored by filtering).
[root@localhost ~]# pvcreate /dev/sdb1 #把sdb1做成物理卷PV，也可以用下面的写法，一次性把所有主分区或逻辑分区做成物理卷PV
Physical volume "/dev/sdb1" successfully created.
[root@localhost ~]# pvcreate /dev/sdb2 /dev/sdc1 /dev/sdc5
Physical volume "/dev/sdb2" successfully created.
Physical volume "/dev/sdc1" successfully created.
Physical volume "/dev/sdc5" successfully created.
[root@localhost ~]# pvdisplay #查看物理卷详细信息
--- 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 610jgI-z9pr-N5H1-R1Qv-jVMh-cMOD-2VKNm5
"/dev/sdb1" is a new physical volume of "10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID l65LfK-FxkO-I8ux-0Lj6-jQB1-ev6d-jl4D8v
"/dev/sdc1" is a new physical volume of "10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc1
VG Name
PV Size 10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID olFzUh-w2jf-sK32-i4lr-oYHP-zWTf-dKmgYw
"/dev/sdc5" is a new physical volume of "<10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc5
VG Name
PV Size <10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 54wYXO-sN3e-Lyc6-2ZQg-YMkH-6khg-TqbKOA
"/dev/sdb2" is a new physical volume of "<10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb2
VG Name
PV Size <10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID aqkWHa-RIxf-15Y9-mgLw-x82r-thpL-kxzYhc
[root@localhost ~]# pvs #显示所有的物理卷，大小都是10G（分区的时候分配的）
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 lvm2 --- 10.00g 10.00g
/dev/sdb2 lvm2 --- <10.00g <10.00g
/dev/sdc1 lvm2 --- 10.00g 10.00g
/dev/sdc5 lvm2 --- <10.00g <10.00g创建卷组
[root@localhost ~]# vgcreate VGtest1 /dev/sdb1 /dev/sdc1 #创建卷组1，卷组的PV物理卷，可以是不同磁盘，即整合了所有磁盘分区做成资源池
Volume group "VGtest1" successfully created
[root@localhost ~]# vgcreate VGtest2 /dev/sdb2 /dev/sdc5 #创建卷组2
Volume group "VGtest2" successfully created
[root@localhost ~]# vgs #显示所有卷组信息
VG #PV #LV #SN Attr VSize VFree
VGtest1 2 0 0 wz--n- 19.99g 19.99g
VGtest2 2 0 0 wz--n- 19.99g 19.99g
centos 1 2 0 wz--n- <19.00g 0
[root@localhost ~]# vgdisplay #查看所有卷组的详细信息
--- 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 <19.00 GiB
PE Size 4.00 MiB
Total PE 4863
Alloc PE / Size 4863 / <19.00 GiB
Free PE / Size 0 / 0
VG UUID FjdwU1-IYgt-Q6r2-uGm7-q1de-g0yh-EsGm64
--- Volume group ---
VG Name VGtest1
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 19.99 GiB
PE Size 4.00 MiB
Total PE 5118
Alloc PE / Size 0 / 0
Free PE / Size 5118 / 19.99 GiB
VG UUID pk62Bc-lRQW-iXim-VUng-PrIk-s9WR-10uctH
--- Volume group ---
VG Name VGtest2
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 19.99 GiB
PE Size 4.00 MiB
Total PE 5118
Alloc PE / Size 0 / 0
Free PE / Size 5118 / 19.99 GiB
VG UUID XsUyyE-1OSa-Xbno-L0W3-cL3E-XmeH-qb3QWW创建逻辑卷
[root@localhost ~]# lvcreate -n LVtest1 -L 1G VGtest1 #-n表示创建逻辑卷名，-L表示分配逻辑卷的空间大小，VGtest1表示在卷组VGtest1上创建逻辑卷LVtest1
Logical volume "LVtest1" created.
[root@localhost ~]# lvcreate -n LVtest2 -L 1G VGtest2
Logical volume "LVtest2" created.
[root@localhost ~]# lvs #显示逻辑卷的信息（大小为1G，上面分配的）
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
LVtest1 VGtest1 -wi-a----- 1.00g
LVtest2 VGtest2 -wi-a----- 1.00g
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
[root@localhost ~]# lvdisplay #显示逻辑卷的详细信息
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID gS0ted-R1jU-NKWR-rpFb-quUd-Yu7w-c0VfGz
LV Write Access read/write
LV Creation host, time localhost, 2018-09-14 09:38:10 -0400
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 LTcnK5-ufCZ-5Cwx-Lpfi-Frgo-NMBm-OEE73C
LV Write Access read/write
LV Creation host, time localhost, 2018-09-14 09:38:10 -0400
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
--- Logical volume ---
LV Path /dev/VGtest1/LVtest1
LV Name LVtest1
VG Name VGtest1
LV UUID PMv1Zv-WtJy-13v4-1GBc-5WaB-mcpk-f7dN22
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2018-10-13 11:48:28 -0400
LV Status available
# open 0
LV Size 1.00 GiB
Current LE 256
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/VGtest2/LVtest2
LV Name LVtest2
VG Name VGtest2
LV UUID HCk2OB-3iVy-Ryma-rKeH-kIie-NYKr-ZVkiIf
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2018-10-13 11:48:47 -0400
LV Status available
# open 0
LV Size 1.00 GiB
Current LE 256
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:3
会创建对应的目录和文件
[root@localhost ~]# ls -l /dev/VGtest1/LVtest1
lrwxrwxrwx. 1 root root 7 Oct 13 11:48 /dev/VGtest1/LVtest1 -> ../dm-2
[root@localhost ~]# ls -l /dev/d
disk/ dm-0 dm-1 dm-2 dm-3 dmmidi dri/
[root@localhost ~]# ls -l /dev/dm-2
brw-rw----. 1 root disk 253, 2 Oct 13 11:48 /dev/dm-2格式化LV逻辑卷
[root@localhost ~]# mke2fs -t ext4 /dev/VGtest1/LVtest1 #物理卷需要格式化之后才能使用，格式化为ext4格式
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
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
[root@localhost ~]# mkfs.ext4 /dev/VGtest2/LVtest2 #也可以使用这种方式格式化
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
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done挂载LV逻辑卷
[root@localhost ~]# mkdir /appdata
[root@localhost ~]# mkdir /applog
[root@localhost ~]# mount /dev/VGtest1/LVtest1 /appdata #把LV逻辑卷挂载到实际的目录
[root@localhost ~]# mount /dev/VGtest2/LVtest2 /applog
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 17G 1.2G 16G 7% /
devtmpfs 482M 0 482M 0% /dev
tmpfs 493M 0 493M 0% /dev/shm
tmpfs 493M 6.8M 486M 2% /run
tmpfs 493M 0 493M 0% /sys/fs/cgroup
/dev/sda1 1014M 125M 890M 13% /boot
tmpfs 99M 0 99M 0% /run/user/0
/dev/mapper/VGtest1-LVtest1 976M 2.6M 907M 1% /appdata
/dev/mapper/VGtest2-LVtest2 976M 2.6M 907M 1% /applog
[root@localhost ~]# mount |grep VGtest
/dev/mapper/VGtest1-LVtest1 on /appdata type ext4 (rw,relatime,seclabel,data=ordered)
/dev/mapper/VGtest2-LVtest2 on /applog type ext4 (rw,relatime,seclabel,data=ordered)
永久挂载LV逻辑卷
[root@localhost ~]# vim /etc/fstab
#
# /etc/fstab
# Created by anaconda on Fri Sep 14 09:38:12 2018
#
# 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=944557a0-3f7c-434d-8202-c960db70b860 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
/dev/VGtest1/LVtest1 /appdata ext4 defaults 0 0
/dev/VGtest2/LVtest2 /applog ext4 defaults 0 0
~
~
"/etc/fstab" 13L, 617C written
[root@localhost ~]# mount -a #重新加载/etc/fstab文件VG卷组扩容
新建一个PV物理卷，然后加入VG即可（fdisk创建分区->修改分区类型Linux LVM->向内核注册新分区->创建物理卷->把物理卷加入需要扩容的卷组）。
发现卷组pv空间不够，我们需要扩大卷组空间，现在系统上新增了一块20G的硬盘/dev/sdc。
[root@localhost ~]# fdisk /dev/sdd #把新添加的磁盘进行分区
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.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xc29c0ac3.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p #主分区
Partition number (1-4, default 1):
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +5G
Partition 1 of type Linux and of size 5 GiB is set
Command (m for help): t #修改分区类型
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sdd: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xc29c0ac3
Device Boot Start End Blocks Id System
/dev/sdd1 2048 10487807 5242880 8e Linux LVM
Command (m for help): w #保存分区信息
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# partprobe /dev/sdd #更新内核分区表
[root@localhost ~]# pvcreate /dev/sdd1 #创建物理卷PV
Physical volume "/dev/sdd1" successfully created.
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 VGtest1 lvm2 a-- <10.00g <9.00g
/dev/sdb2 VGtest2 lvm2 a-- <10.00g <9.00g
/dev/sdc1 VGtest1 lvm2 a-- <10.00g <10.00g
/dev/sdc5 VGtest2 lvm2 a-- <10.00g <10.00g
/dev/sdd1 lvm2 --- 5.00g 5.00g
[root@localhost ~]# vgextend VGtest1 /dev/sdd1 #扩展VG卷组容量，把物理卷加入卷组
Volume group "VGtest1" successfully extended
[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VGtest1 3 1 0 wz--n- <24.99g <23.99g
VGtest2 2 1 0 wz--n- 19.99g 18.99g
centos 1 2 0 wz--n- <19.00g 0
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 VGtest1 lvm2 a-- <10.00g <9.00g
/dev/sdb2 VGtest2 lvm2 a-- <10.00g <9.00g
/dev/sdc1 VGtest1 lvm2 a-- <10.00g <10.00g
/dev/sdc5 VGtest2 lvm2 a-- <10.00g <10.00g
/dev/sdd1 VGtest1 lvm2 a-- <5.00g <5.00gLV逻辑卷扩容 (支持在线扩展)
在线将/dev/VGtest/LVtest1 扩展到4G，并且要求数据可以正常访问
[root@localhost ~]# echo "this is a test for LVM" >/appdata/test
[root@localhost ~]# cat /appdata/test #在挂载的逻辑卷里添加数据，用来测试在逻辑卷扩容是否会破坏原有数据
this is a test for LVM
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
LVtest1 VGtest1 -wi-ao---- 1.00g
LVtest2 VGtest2 -wi-ao---- 1.00g
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
[root@localhost ~]# lvextend -L +2G /dev/VGtest1/LVtest1 #扩容逻辑卷LVtest1，增加2G空间容量（从对应的卷组中划分空间容量）
Size of logical volume VGtest1/LVtest1 changed from 1.00 GiB (256 extents) to 3.00 GiB (768 extents).
Logical volume VGtest1/LVtest1 successfully resized.
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
LVtest1 VGtest1 -wi-ao---- 3.00g
LVtest2 VGtest2 -wi-ao---- 1.00g
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
[root@localhost ~]# resize2fs /dev/VGtest1/LVtest1 #使用resize2fs命令来进行确认增加容量，前面的步骤只是初步分配，还不能实际使用，需要此步骤来确定实际分配使用
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/VGtest1/LVtest1 is mounted on /appdata; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/VGtest1/LVtest1 is now 786432 blocks long.
xfs系统确认实际使用的命令
xfs_growfs /dev/VGtest1/LVtest1
查看挂载目录的空间容量大小
[root@localhost ~]# df -h|grep VGtest
/dev/mapper/VGtest2-LVtest2 976M 2.6M 907M 1% /applog
/dev/mapper/VGtest1-LVtest1 3.0G 3.1M 2.8G 1% /appdata
数据并没有受损
[root@localhost ~]# cat /appdata/test
this is a test for LVM缩减逻辑卷LV
缩减逻辑卷的注意事项：
1、查看逻辑卷使用空间状况
2、不能在线缩减，得先卸载 切记
3、确保缩减后的空间大小依然能存储原有的所有数据
4、在缩减之前应该先强行检查文件，以确保文件系统处于一至性状态
[root@localhost ~]# e2fsck -f /dev/VGtest1/LVtest1 #处于挂载状态的LV逻辑卷无法强制检查
e2fsck 1.42.9 (28-Dec-2013)
/dev/VGtest1/LVtest1 is mounted.
e2fsck: Cannot continue, aborting.
[root@localhost ~]# umount /dev/VGtest1/LVtest1 #取消逻辑卷挂载
[root@localhost ~]# e2fsck -f /dev/VGtest1/LVtest1 #检查逻辑卷
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/VGtest1/LVtest1: 12/196608 files (0.0% non-contiguous), 21309/786432 blocks
[root@localhost ~]# resize2fs /dev/VGtest1/LVtest1 1G #首先需要确定缩减逻辑卷到多大空间容量，-1G表示缩减1G大小，1G表示缩减至1G（原来空间是3G）
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/VGtest1/LVtest1 to 262144 (4k) blocks.
The filesystem on /dev/VGtest1/LVtest1 is now 262144 blocks long.
[root@localhost ~]# lvreduce -L 1G /dev/VGtest1/LVtest1 #再进行逻辑卷LV容量缩减
WARNING: Reducing active logical volume to 1.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce VGtest1/LVtest1? [y/n]: y
Size of logical volume VGtest1/LVtest1 changed from 3.00 GiB (768 extents) to 1.00 GiB (256 extents).
Logical volume VGtest1/LVtest1 successfully resized.
[root@localhost ~]# mount /dev/VGtest1/LVtest1 /appdata #重新挂载逻辑卷
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
LVtest1 VGtest1 -wi-ao---- 1.00g
LVtest2 VGtest2 -wi-ao---- 500.00m
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
[root@localhost ~]# df -h|grep VGtest
/dev/mapper/VGtest2-LVtest2 460M 1.6M 424M 1% /applog
/dev/mapper/VGtest1-LVtest1 976M 2.6M 914M 1% /appdata
[root@localhost ~]# cat /appdata/test
this is a test for LVM缩减磁盘空间
发现物理磁盘空间使用不足，将其中一块硬盘或分区拿掉，避免磁盘浪费
1、pvmove /dev/sdb1 #将/dev/sdb1上存储的数据移到其它物理卷中
2、vgreduce VGtest /dev/sdb1 #将/dev/sdb1从VGtest卷组中移除
3、pvremove /dev/sdb1 #将/dev/sdb1从物理卷上移除
[root@localhost appdata]# touch stu{0..100}
[root@localhost appdata]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 VGtest1 lvm2 a-- <10.00g <9.00g
/dev/sdb2 VGtest2 lvm2 a-- <10.00g <9.51g
/dev/sdc1 VGtest1 lvm2 a-- <10.00g <10.00g
/dev/sdc5 VGtest2 lvm2 a-- <10.00g <10.00g
/dev/sdd1 VGtest1 lvm2 a-- <5.00g <5.00g
[root@localhost appdata]# pvmove /dev/sdb1 #把sdb1磁盘分区的数据转移到其它磁盘上
/dev/sdb1: Moved: 6.64%
/dev/sdb1: Moved: 100.00%
[root@localhost appdata]# vgreduce VGtest1 /dev/sdb1 #把分区sdb1从VG卷组中移除
Removed "/dev/sdb1" from volume group "VGtest1"
[root@localhost appdata]# pvremove /dev/sdb1 #把sdb1分区从PV物理卷中释放出来
Labels on physical volume "/dev/sdb1" successfully wiped.
#如果磁盘划分了多个分区，做成多个物理卷加入了卷组，那么可以能重复以上步骤，把所有的空间都从卷组和物理卷中释放，然后可以拿走这块磁盘做它用
实现快照，进行备份还原
在/mnt/lvm目录上，我们将原始的目录文件进行快照，然后将/LVtets1目录中的内容清空，并进行还原
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
LVtest1 VGtest1 -wi-ao---- 1.00g
LVtest2 VGtest2 -wi-ao---- 500.00m
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
[root@localhost ~]# cat /appdata/test
this is a test for LVM
[root@localhost ~]# df -h|grep VGtest
/dev/mapper/VGtest2-LVtest2 460M 1.6M 424M 1% /applog
/dev/mapper/VGtest1-LVtest1 976M 2.6M 914M 1% /appdata
[root@localhost ~]# lvcreate -L 20M -n appdatabackup -s -p r /dev/VGtest1/LVtest1 #利用LVtest1逻辑卷，快照形成一个备份的物理卷appdatabackup（逻辑卷快照功能）
Using default stripesize 64.00 KiB.
Logical volume "appdatabackup" created.
[root@localhost ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
LVtest1 VGtest1 owi-aos--- 1.00g
appdatabackup VGtest1 sri-a-s--- 20.00m LVtest1 0.06
LVtest2 VGtest2 -wi-ao---- 500.00m
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
[root@localhost ~]# mkdir /tmp/backup
[root@localhost ~]# mount /dev/VGtest1/appdatabackup /tmp/backup #把快照的逻辑卷挂载到目录上
mount: /dev/mapper/VGtest1-appdatabackup is write-protected, mounting read-only
[root@localhost ~]# cat /tmp/backup/test
this is a test for LVM
[root@localhost ~]# ls -l /appdata/test
-rw-r--r--. 1 root root 23 Oct 13 12:33 /appdata/test
[root@localhost ~]# ls -l /tmp/backup/test
-rw-r--r--. 1 root root 23 Oct 13 12:33 /tmp/backup/test
[root@localhost ~]# rm -rf /appdata/test #删除LVtest1逻辑卷的数据
[root@localhost ~]# ls -l /appdata/test
ls: cannot access /appdata/test: No such file or directory
[root@localhost ~]# cp /tmp/backup/test /appdata/ #从快照中恢复数据到逻辑卷LVtest1上
[root@localhost ~]# ls -l /appdata/test
-rw-r--r--. 1 root root 23 Oct 13 13:06 /appdata/test
[root@localhost ~]# df -h|grep VGtest
/dev/mapper/VGtest2-LVtest2 460M 1.6M 424M 1% /applog
/dev/mapper/VGtest1-LVtest1 976M 2.6M 914M 1% /appdata
/dev/mapper/VGtest1-appdatabackup 976M 2.6M 914M 1% /tmp/backup知识扩展
resize2fs命令
resize2fs命令被用来增大或者收缩未加载的“ext2/ext3”文件系统的大小。如果文件系统是处于mount状态下，那么它只能做到扩容，前提条件是内核支持在线resize。，linux kernel 2.6支持在mount状态下扩容但仅限于ext3文件系统。
-d：打开调试特性；
-p：打印已完成的百分比进度条；
-f：强制执行调整大小操作，覆盖掉安全检查操作；
-F：开始执行调整大小前，刷新文件系统设备的缓冲区
如果是xfs文件系统，则需要使用xfs_growfs命令
e2fsck命令
e2fsck是检查ext2、ext3、ext4等文件系统的正确性。
补充说明：
e2fsck执行后的传回值及代表意义如下：
0 没有任何错误发生。
1 文件系统发生错误，并且已经修正。
2 文件系统发生错误，并且已经修正。
4 文件系统发生错误，但没有修正。
8 运作时发生错误。
16 使用的语法发生错误。
128 共享的函数库发生错误。
参 数：
-a 不询问使用者意见，便自动修复文件系统。
-b
-B <区块大小> 指定区块的大小，单位为字节。
-c 一并执行badblocks，以标示损坏的区块。
-C 将检查过程的信息完整记录在file descriptor中，使得整个检查过程都能完整监控。
-d 显示排错信息。
-f 即使文件系统没有错误迹象，仍强制地检查正确性。
-F 执行前先清除设备的缓冲区。
-l <文件> 将文件中指定的区块加到损坏区块列表。
-L <文件> 先清除损坏区块列表，再将文件中指定的区块加到损坏区块列表。因此损坏区块列表的区块跟文件中指定的区块是一样的。
-n 以只读模式开启文件系统，并采取非互动方式执行，所有的问题对话均设置以"no"回答。
-p 不询问使用者意见，便自动修复文件系统。
-r 此参数只为了兼容性而存在，并无实际作用。
-s 如果文件系统的字节顺序不适当，就交换字节顺序，否则不做任何动作。
-S 不管文件系统的字节顺序，一律交换字节顺序。
-t 显示时间信息。
-v 执行时显示详细的信息。
-V 显示版本信息。
-y 采取非互动方式执行，所有的问题均设置以"yes"回答。
转载于:https://blog.51cto.com/13691477/2299707