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一、LVM介绍
在我们管理Linux磁盘的时候，通常会遇到这么一种情况。在最初规划Linux的磁盘的时候，我们给某个分区划分了一定量的磁盘空间，使用一段时间后，发现我们规划的磁盘空间不足了，这个时候怎么办？我们肯定要想办法给扩容呀，找一块磁盘分区，格式化，然后挂载，然后把数据拷贝到新加的磁盘上，然后把原有的磁盘卸载掉，通常我们是这样做的。这样一来虽然达到了扩容的目的，但是费时费力；如果第二次扩容，空间还是不够，我们又要重复上面的步骤；如果分配的磁盘空间过大，使用了很久才发现它根本用不到那么多空间，这个时候是不是又要调整呀，听着就感觉很繁琐。这时候你肯定要想有没有那种可挂载上一块盘，我们利用某种管理手段，可以在线的调整磁盘的空间，这样有节约了时间，也可实现弹性管理磁盘。对，lvm就有这样的功能。
LVM（logical volume manager）逻辑卷管理，它可以弹性的管理文件系统的容量，LVM的工作原理是将一个或多个底层块设备组织成一个逻辑设备，这个逻辑设备可以在未来新增或移除其他的分区到这个逻辑设备中，从而实现了弹性管理磁盘。
PV：物理卷（physical volume）；物理卷就是指硬盘分区或从逻辑上与磁盘分区具有同样功能的设备（如raid），是LVM的基本储存逻辑块，但和基本的物理存储介质（如分区，磁盘等）比较，却包含有与LVM相关的管理参数
VG：卷组（volume group）LVM卷组类似于非LVM系统中的物理硬盘，尤其物理卷组成，可以在卷组上创建一个或多个LVM分区（逻辑卷），LVM卷组由一个或多个物理卷组成
LV：逻辑卷（logical volume）LVM的逻辑卷类似非LVM系统中的硬盘分区，在逻辑卷之上可以创建文件系统。
LVM就是将一些零碎的磁盘分区（PV）合并成一个较大的磁盘（VG），然后在根据需要对这个较大的磁盘（VG）进行划分成不同的大小分区（LV），这些小的分区（LV）是可以动态的扩展和缩小的，这就是LVM的逻辑卷管理过程。所谓LVM的大磁盘就是将许多PV整合成的VG，那么这个大磁盘最大可达到多少容量呢？我们知道在文件系统里面数据存储的最小单位是块（block），不过在LVM当中数据储存的最小单位是PE，PE的的作用同block的作用一样，需要注意到是LVM默认使用的PE大小是4M，而LVM的VG最多能包含65534个PE，也就是说默认LVM的VG会有4×65534M/1024M=256G，所以PE的大小决定了VG的最大容量，当然我们在创建VG的时候可指定PE大小，从而来决定VG的大小。
二、LVM实现
1）前期准备几块硬盘或者分区来模拟PV
[root@test-centos7-node1 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 50G 0 disk
├─sda1 8:1 0 2G 0 part /boot
├─sda2 8:2 0 2G 0 part [SWAP]
└─sda3 8:3 0 46G 0 part /
sdb 8:16 0 50G 0 disk
sr0 11:0 1 792M 0 rom
[root@test-centos7-node1 ~]# fdisk /dev/sdb
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 0x6180123f.
Command (m for help): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes, 104857600 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: 0x6180123f
Device Boot Start End Blocks Id System
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 (2048-104857599, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-104857599, default 104857599): +10G
Partition 1 of type Linux and of size 10 GiB is set
Command (m for help): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes, 104857600 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: 0x6180123f
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20973567 10485760 83 Linux
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p
Partition number (2-4, default 2):
First sector (20973568-104857599, default 20973568):
Using default value 20973568
Last sector, +sectors or +size{K,M,G} (20973568-104857599, default 104857599): +10G
Partition 2 of type Linux and of size 10 GiB is set
Command (m for help): t
Partition number (1,2, default 2):
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): p
Partition number (3,4, default 3):
First sector (41945088-104857599, default 41945088):
Using default value 41945088
Last sector, +sectors or +size{K,M,G} (41945088-104857599, default 104857599): +10G
Partition 3 of type Linux and of size 10 GiB is set
Command (m for help): t
Partition number (1-3, default 3):
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: 53.7 GB, 53687091200 bytes, 104857600 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: 0x6180123f
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20973567 10485760 8e Linux LVM
/dev/sdb2 20973568 41945087 10485760 8e Linux LVM
/dev/sdb3 41945088 62916607 10485760 8e Linux LVM
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@test-centos7-node1 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 50G 0 disk
├─sda1 8:1 0 2G 0 part /boot
├─sda2 8:2 0 2G 0 part [SWAP]
└─sda3 8:3 0 46G 0 part /
sdb 8:16 0 50G 0 disk
├─sdb1 8:17 0 10G 0 part
├─sdb2 8:18 0 10G 0 part
└─sdb3 8:19 0 10G 0 part
sr0 11:0 1 792M 0 rom
[root@test-centos7-node1 ~]#
说明：这里是用的分区来模拟硬盘当作PV，这里需要注意一点，就是我们分区完保存后，可能存在不同不到问题，就是我们分区完用lsblk看不到分区，可用 partprobe来同步分区信息。centos6 使用partx -a /dev/sdb来增加分区同步到内存，如果是删除某个分区，就需要执行partx -d -nr # /dev/sdb 此命令表示从/dev/sdb的分区信息中删除sdb#分区信息，并同步到内存中。这里还需要注意一点的是我们分区的类型要选8e 表示Linux LVM
2）装lvm2这个包
[root@test-centos7-node1 ~]# lvs
-bash: lvs: command not found
[root@test-centos7-node1 ~]# yum info lvm2
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
Available Packages
Name : lvm2
Arch : x86_64
Epoch : 7
Version : 2.02.185
Release : 2.el7_7.2
Size : 1.3 M
Repo : updates/7/x86_64
Summary : Userland logical volume management tools
URL : http://sources.redhat.com/lvm2
License : GPLv2
Description : LVM2 includes all of the support for handling read/write operations on
: physical volumes (hard disks, RAID-Systems, magneto optical, etc.,
: multiple devices (MD), see mdadm(8) or even loop devices, see
: losetup(8)), creating volume groups (kind of virtual disks) from one
: or more physical volumes and creating one or more logical volumes
: (kind of logical partitions) in volume groups.
[root@test-centos7-node1 ~]# yum install lvm2 -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
Resolving Dependencies
--> Running transaction check
---> Package lvm2.x86_64 7:2.02.185-2.el7_7.2 will be installed
--> Processing Dependency: lvm2-libs = 7:2.02.185-2.el7_7.2 for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Processing Dependency: device-mapper-persistent-data >= 0.7.0-0.1.rc6 for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Processing Dependency: liblvm2app.so.2.2(Base)(64bit) for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Processing Dependency: libdevmapper.so.1.02(DM_1_02_141)(64bit) for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Processing Dependency: libdevmapper-event.so.1.02(Base)(64bit) for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Processing Dependency: liblvm2app.so.2.2()(64bit) for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Processing Dependency: libdevmapper-event.so.1.02()(64bit) for package: 7:lvm2-2.02.185-2.el7_7.2.x86_64
--> Running transaction check
---> Package device-mapper-event-libs.x86_64 7:1.02.158-2.el7_7.2 will be installed
---> Package device-mapper-libs.x86_64 7:1.02.140-8.el7 will be updated
--> Processing Dependency: device-mapper-libs = 7:1.02.140-8.el7 for package: 7:device-mapper-1.02.140-8.el7.x86_64
---> Package device-mapper-libs.x86_64 7:1.02.158-2.el7_7.2 will be an update
---> Package device-mapper-persistent-data.x86_64 0:0.8.5-1.el7 will be installed
---> Package lvm2-libs.x86_64 7:2.02.185-2.el7_7.2 will be installed
--> Processing Dependency: device-mapper-event = 7:1.02.158-2.el7_7.2 for package: 7:lvm2-libs-2.02.185-2.el7_7.2.x86_64
--> Running transaction check
---> Package device-mapper.x86_64 7:1.02.140-8.el7 will be updated
---> Package device-mapper.x86_64 7:1.02.158-2.el7_7.2 will be an update
---> Package device-mapper-event.x86_64 7:1.02.158-2.el7_7.2 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
============================================================================================================================
Package Arch Version Repository Size
============================================================================================================================
Installing:
lvm2 x86_64 7:2.02.185-2.el7_7.2 updates 1.3 M
Installing for dependencies:
device-mapper-event x86_64 7:1.02.158-2.el7_7.2 updates 190 k
device-mapper-event-libs x86_64 7:1.02.158-2.el7_7.2 updates 189 k
device-mapper-persistent-data x86_64 0.8.5-1.el7 base 423 k
lvm2-libs x86_64 7:2.02.185-2.el7_7.2 updates 1.1 M
Updating for dependencies:
device-mapper x86_64 7:1.02.158-2.el7_7.2 updates 294 k
device-mapper-libs x86_64 7:1.02.158-2.el7_7.2 updates 322 k
Transaction Summary
============================================================================================================================
Install 1 Package (+4 Dependent packages)
Upgrade ( 2 Dependent packages)
Total download size: 3.8 M
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
(1/7): device-mapper-event-1.02.158-2.el7_7.2.x86_64.rpm | 190 kB 00:00:00
(2/7): device-mapper-event-libs-1.02.158-2.el7_7.2.x86_64.rpm | 189 kB 00:00:00
(3/7): device-mapper-libs-1.02.158-2.el7_7.2.x86_64.rpm | 322 kB 00:00:00
(4/7): lvm2-2.02.185-2.el7_7.2.x86_64.rpm | 1.3 MB 00:00:00
(5/7): device-mapper-1.02.158-2.el7_7.2.x86_64.rpm | 294 kB 00:00:00
(6/7): lvm2-libs-2.02.185-2.el7_7.2.x86_64.rpm | 1.1 MB 00:00:00
(7/7): device-mapper-persistent-data-0.8.5-1.el7.x86_64.rpm | 423 kB 00:00:00
----------------------------------------------------------------------------------------------------------------------------
Total 4.3 MB/s | 3.8 MB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : 7:device-mapper-1.02.158-2.el7_7.2.x86_64 1/9
Updating : 7:device-mapper-libs-1.02.158-2.el7_7.2.x86_64 2/9
Installing : 7:device-mapper-event-libs-1.02.158-2.el7_7.2.x86_64 3/9
Installing : 7:device-mapper-event-1.02.158-2.el7_7.2.x86_64 4/9
Installing : 7:lvm2-libs-2.02.185-2.el7_7.2.x86_64 5/9
Installing : device-mapper-persistent-data-0.8.5-1.el7.x86_64 6/9
Installing : 7:lvm2-2.02.185-2.el7_7.2.x86_64 7/9
Created symlink from /etc/systemd/system/sysinit.target.wants/lvm2-lvmpolld.socket to /usr/lib/systemd/system/lvm2-lvmpolld.socket.
Cleanup : 7:device-mapper-1.02.140-8.el7.x86_64 8/9
Cleanup : 7:device-mapper-libs-1.02.140-8.el7.x86_64 9/9
Verifying : 7:device-mapper-libs-1.02.158-2.el7_7.2.x86_64 1/9
Verifying : 7:device-mapper-1.02.158-2.el7_7.2.x86_64 2/9
Verifying : device-mapper-persistent-data-0.8.5-1.el7.x86_64 3/9
Verifying : 7:lvm2-2.02.185-2.el7_7.2.x86_64 4/9
Verifying : 7:lvm2-libs-2.02.185-2.el7_7.2.x86_64 5/9
Verifying : 7:device-mapper-event-1.02.158-2.el7_7.2.x86_64 6/9
Verifying : 7:device-mapper-event-libs-1.02.158-2.el7_7.2.x86_64 7/9
Verifying : 7:device-mapper-1.02.140-8.el7.x86_64 8/9
Verifying : 7:device-mapper-libs-1.02.140-8.el7.x86_64 9/9
Installed:
lvm2.x86_64 7:2.02.185-2.el7_7.2
Dependency Installed:
device-mapper-event.x86_64 7:1.02.158-2.el7_7.2 device-mapper-event-libs.x86_64 7:1.02.158-2.el7_7.2
device-mapper-persistent-data.x86_64 0:0.8.5-1.el7 lvm2-libs.x86_64 7:2.02.185-2.el7_7.2
Dependency Updated:
device-mapper.x86_64 7:1.02.158-2.el7_7.2 device-mapper-libs.x86_64 7:1.02.158-2.el7_7.2
Complete!
[root@test-centos7-node1 ~]#
说明：最小化安装系统默认系统上没有安装这个包的，所以我们需要把这个包装上才可创建LVM
3）创建PV
[root@test-centos7-node1 ~]# pvcreate /dev/sdb{1,2,3}
Physical volume "/dev/sdb1" successfully created.
Physical volume "/dev/sdb2" successfully created.
Physical volume "/dev/sdb3" successfully created.
[root@test-centos7-node1 ~]# pvscan
PV /dev/sdb1 lvm2 [10.00 GiB]
PV /dev/sdb3 lvm2 [10.00 GiB]
PV /dev/sdb2 lvm2 [10.00 GiB]
Total: 3 [30.00 GiB] / in use: 0 [0 ] / in no VG: 3 [30.00 GiB]
[root@test-centos7-node1 ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 --- 10.00g 10.00g
/dev/sdb2 lvm2 --- 10.00g 10.00g
/dev/sdb3 lvm2 --- 10.00g 10.00g
[root@test-centos7-node1 ~]# pvdisplay
"/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 MsszES-YPdm-YGQl-7rgg-B6gX-Q4xu-T8m1gz
"/dev/sdb3" is a new physical volume of "10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb3
VG Name
PV Size 10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID BMMx8p-zu9O-ns61-G9DU-iKMR-NmZO-crCjlR
"/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 LPynpW-twlu-fxwg-OlCT-jA2A-R5UI-fvqWLj
[root@test-centos7-node1 ~]#
说明：pvcreate 命令表示创建PV 后面跟硬盘或分区对应的设备文件，pvscan 命令作用是搜索系统里面任何具有PV属性的磁碟，PV属性就是通过pvcreate创建过的磁碟，pvs是查看pv简要情况，pvdisplay 查看pv的详细信息。当然我们要移除某块盘，让其不具备PV属性，可以用pvremove + 磁盘的设备文件路径
[root@test-centos7-node1 ~]# pvremove /dev/sdb3 Labels on physical volume "/dev/sdb3" successfully wiped. [root@test-centos7-node1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb1 lvm2 --- 10.00g 10.00g /dev/sdb2 lvm2 --- 10.00g 10.00g [root@test-centos7-node1 ~]#
说明：移除pv的前提是它没有在任何VG里面才可做移除，否则移除不了
4）创建VG
[root@test-centos7-node1 ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 --- 10.00g 10.00g
/dev/sdb2 lvm2 --- 10.00g 10.00g
[root@test-centos7-node1 ~]# pvcreate /dev/sdb3
Physical volume "/dev/sdb3" successfully created.
[root@test-centos7-node1 ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 --- 10.00g 10.00g
/dev/sdb2 lvm2 --- 10.00g 10.00g
/dev/sdb3 lvm2 --- 10.00g 10.00g
[root@test-centos7-node1 ~]# vgcreate test -s 8M /dev/sdb{1,2,3}
Volume group "test" successfully created
[root@test-centos7-node1 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
test 3 0 0 wz--n- <29.98g <29.98g
[root@test-centos7-node1 ~]# vgscan
Reading volume groups from cache.
Found volume group "test" using metadata type lvm2
[root@test-centos7-node1 ~]# vgdisplay
--- Volume group ---
VG Name test
System ID
Format lvm2
Metadata Areas 3
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 3
Act PV 3
VG Size <29.98 GiB
PE Size 8.00 MiB
Total PE 3837
Alloc PE / Size 0 / 0
Free PE / Size 3837 / <29.98 GiB
VG UUID 31vxAP-L5jb-8Yxm-25m2-LdD0-ee8R-sdTjum
[root@test-centos7-node1 ~]# vgreduce test /dev/sdb3
Removed "/dev/sdb3" from volume group "test"
[root@test-centos7-node1 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
test 2 0 0 wz--n- 19.98g 19.98g
[root@test-centos7-node1 ~]# vgcreate test2 /dev/sdb3
Volume group "test2" successfully created
[root@test-centos7-node1 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
test 2 0 0 wz--n- 19.98g 19.98g
test2 1 0 0 wz--n- <10.00g <10.00g
[root@test-centos7-node1 ~]# vgdisplay test2
--- Volume group ---
VG Name test2
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
VG Size <10.00 GiB
PE Size 4.00 MiB
Total PE 2559
Alloc PE / Size 0 / 0
Free PE / Size 2559 / <10.00 GiB
VG UUID rc94SP-JAlk-63Rw-n5xz-qB0d-grnT-ItrMvT
[root@test-centos7-node1 ~]# vgremove test2
Volume group "test2" successfully removed
[root@test-centos7-node1 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
test 2 0 0 wz--n- 19.98g 19.98g
[root@test-centos7-node1 ~]#
说明：同样的vgcreate 表示创建VG 其用法格式是vgcreate VGNAME [option] 储存设备路径 其中-s表示指定PE的大小，VGNAME表示VG的名称，需要说明的是，指定名称不能和系统现有的VG名称相同；vgs查看系统上所有VG的简要信息，vgscan搜寻系统上面是否有VG，vgdisplay查看所有VG的详细信息，当然此例中只有一个，我们也可在后面指定查看某个VG的详细信息，只需要指定其VG名称即可；有关vg的命令有很多其中vgreduce的作用是在VG内移除PV，vgremove的作用是删除一个VG，这两个命令都需要在其后指定要操作的VG名称
5）创建LV
[root@test-centos7-node1 ~]# lvs [root@test-centos7-node1 ~]# lvcreate -L 2G -n aaa test Logical volume "aaa" created. [root@test-centos7-node1 ~]# lvcreate -L 3G -n bbb test Logical volume "bbb" created. [root@test-centos7-node1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert aaa test -wi-a----- 2.00g bbb test -wi-a----- 3.00g [root@test-centos7-node1 ~]# lvscan ACTIVE '/dev/test/aaa' [2.00 GiB] inherit ACTIVE '/dev/test/bbb' [3.00 GiB] inherit [root@test-centos7-node1 ~]# lvdisplay --- Logical volume --- LV Path /dev/test/aaa LV Name aaa VG Name test LV UUID R9weh0-D85B-rMcW-oYSM-dAQb-gIQh-RXxITP LV Write Access read/write LV Creation host, time test-centos7-node1, 2020-01-06 09:05:23 -0500 LV Status available # open 0 LV Size 2.00 GiB Current LE 256 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:0 --- Logical volume --- LV Path /dev/test/bbb LV Name bbb VG Name test LV UUID LYwvZj-ogpf-nwtF-mja6-xwwl-A24W-BslJOu LV Write Access read/write LV Creation host, time test-centos7-node1, 2020-01-06 09:05:34 -0500 LV Status available # open 0 LV Size 3.00 GiB Current LE 384 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:1 [root@test-centos7-node1 ~]# lvresize -L +4G /dev/test/aaa Size of logical volume test/aaa changed from 2.00 GiB (256 extents) to 6.00 GiB (768 extents). Logical volume test/aaa successfully resized. [root@test-centos7-node1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert aaa test -wi-a----- 6.00g bbb test -wi-a----- 3.00g [root@test-centos7-node1 ~]# lvresize -L -1G /dev/test/bbb WARNING: Reducing active logical volume to 2.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce test/bbb"bbb" successfully removed [root@test-centos7-node1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert aaa test -wi-a----- 2.00g [root@test-centos7-node1 ~]#
说明：lvcreate 命令作用是创建LV 其中-L表示指定LV的大小，-n表示lv的名称 最后跟VG的名称，表示从那个VG上创建LV；lvs 命令作用是查看系统所有的lv简要信息 ；lvdisplay 查看LV的详细信息，后面可以跟VG的名称表示查看指定VG上的所有LV的详细信息；lvreduce 命令作用是缩减指定LV里的空间，如果指定的大小是负数如-3M 表示缩减3M 如果指定的是 3M 则表示缩减至3M ，这个需要注意，还有这个命令指定大小不能以类似+4M来指定；lvresize此命令的作用是调整LV的容量大小，这个命令指定调整大小+表示增加多少，-表示减少多少，若没有+/-表示调整到指定大小，lvresize和lvreduce这两个命令后面都是跟的lv对应设备的路径（其实不是真的设备路径，是设备的软连接路径），不能指定其名称；lvremove命令作用是删除指定的LV,若指定的是vg名，表示删除该VG上的所有LV，若需要删除某个LV 需要指定其对应设备路径。
到此lvm就已经实现，后续就可以直接格式化，然后挂载使用了
[root@test-centos7-node1 ~]# vgs
VG #PV #LV #SN Attr VSize VFree
test 2 0 0 wz--n- 19.98g 19.98g
[root@test-centos7-node1 ~]# lvcreate -l 100%FREE -n xxx test
WARNING: xfs signature detected on /dev/test/xxx at offset 0. Wipe it"xxx" created.
[root@test-centos7-node1 ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
xxx test -wi-a----- 19.98g
[root@test-centos7-node1 ~]# mkfs.xfs -f /dev/test/xxx
meta-data=/dev/test/xxx isize=512 agcount=4, agsize=1309696 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=5238784, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@test-centos7-node1 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 50G 0 disk
├─sda1 8:1 0 2G 0 part /boot
├─sda2 8:2 0 2G 0 part [SWAP]
└─sda3 8:3 0 46G 0 part /
sdb 8:16 0 50G 0 disk
├─sdb1 8:17 0 10G 0 part
│ └─test-xxx 253:0 0 20G 0 lvm
├─sdb2 8:18 0 10G 0 part
│ └─test-xxx 253:0 0 20G 0 lvm
└─sdb3 8:19 0 10G 0 part
sr0 11:0 1 792M 0 rom
[root@test-centos7-node1 ~]# mount /dev/test/xxx /mnt
[root@test-centos7-node1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 46G 1.6G 45G 4% /
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.6M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sda1 2.0G 135M 1.9G 7% /boot
tmpfs 378M 0 378M 0% /run/user/0
/dev/mapper/test-xxx 20G 33M 20G 1% /mnt
[root@test-centos7-node1 ~]#
三、扩容LV
1）创建PV，并将其加入到VG中
[root@test-centos7-node1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb1 test lvm2 a-- 9.99g 0 /dev/sdb2 test lvm2 a-- 9.99g 0 [root@test-centos7-node1 ~]# vgdisplay --- Volume group --- VG Name test System ID Format lvm2 Metadata Areas 2 Metadata Sequence No 28 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 19.98 GiB PE Size 8.00 MiB Total PE 2558 Alloc PE / Size 2558 / 19.98 GiB Free PE / Size 0 / 0 VG UUID 31vxAP-L5jb-8Yxm-25m2-LdD0-ee8R-sdTjum [root@test-centos7-node1 ~]#
说明：从上面的信息可以看到VG的大小是19.98G 也就是两块PV的大小。现在我们新创建一个pv，然后加到vg里
[root@test-centos7-node1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb1 test lvm2 a-- 9.99g 0 /dev/sdb2 test lvm2 a-- 9.99g 0 [root@test-centos7-node1 ~]# pvcreate /dev/sdb3 Physical volume "/dev/sdb3" successfully created. [root@test-centos7-node1 ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb1 test lvm2 a-- 9.99g 0 /dev/sdb2 test lvm2 a-- 9.99g 0 /dev/sdb3 lvm2 --- 10.00g 10.00g [root@test-centos7-node1 ~]# vgs VG #PV #LV #SN Attr VSize VFree test 2 1 0 wz--n- 19.98g 0 [root@test-centos7-node1 ~]# vgextend test /dev/sdb3 Volume group "test" successfully extended [root@test-centos7-node1 ~]# vgs VG #PV #LV #SN Attr VSize VFree test 3 1 0 wz--n- <29.98g 9.99g [root@test-centos7-node1 ~]# vgdisplay --- Volume group --- VG Name test System ID Format lvm2 Metadata Areas 3 Metadata Sequence No 31 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 1 Max PV 0 Cur PV 3 Act PV 3 VG Size <29.98 GiB PE Size 8.00 MiB Total PE 3837 Alloc PE / Size 2558 / 19.98 GiB Free PE / Size 1279 / 9.99 GiB VG UUID 31vxAP-L5jb-8Yxm-25m2-LdD0-ee8R-sdTjum [root@test-centos7-node1 ~]#
说明：vgextend命令作用是将指定pv加入到指定VG中，VG指定其名称即可，pv需指定其设备路径
2）将新加的VG的PE加入到xxx LV里
[root@test-centos7-node1 ~]# vgs VG #PV #LV #SN Attr VSize VFree test 3 1 0 wz--n- <29.98g 9.99g [root@test-centos7-node1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert xxx test -wi-ao---- 19.98g [root@test-centos7-node1 ~]# lvdisplay --- Logical volume --- LV Path /dev/test/xxx LV Name xxx VG Name test LV UUID ihOo41-gh1L-eSHK-iLXY-UGfF-J6uI-UmVWhF LV Write Access read/write LV Creation host, time test-centos7-node1, 2020-01-06 10:00:08 -0500 LV Status available # open 1 LV Size 19.98 GiB Current LE 2558 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:0 [root@test-centos7-node1 ~]# lvextend -l +100%FREE /dev/test/xxx Size of logical volume test/xxx changed from 19.98 GiB (2558 extents) to <29.98 GiB (3837 extents). Logical volume test/xxx successfully resized. [root@test-centos7-node1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert xxx test -wi-ao---- <29.98g [root@test-centos7-node1 ~]# lvdisplay --- Logical volume --- LV Path /dev/test/xxx LV Name xxx VG Name test LV UUID ihOo41-gh1L-eSHK-iLXY-UGfF-J6uI-UmVWhF LV Write Access read/write LV Creation host, time test-centos7-node1, 2020-01-06 10:00:08 -0500 LV Status available # open 1 LV Size <29.98 GiB Current LE 3837 Segments 3 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:0 [root@test-centos7-node1 ~]# vgs VG #PV #LV #SN Attr VSize VFree test 3 1 0 wz--n- <29.98g 0 [root@test-centos7-node1 ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 50G 0 disk ├─sda1 8:1 0 2G 0 part /boot ├─sda2 8:2 0 2G 0 part [SWAP] └─sda3 8:3 0 46G 0 part / sdb 8:16 0 50G 0 disk ├─sdb1 8:17 0 10G 0 part │ └─test-xxx 253:0 0 30G 0 lvm /mnt ├─sdb2 8:18 0 10G 0 part │ └─test-xxx 253:0 0 30G 0 lvm /mnt └─sdb3 8:19 0 10G 0 part └─test-xxx 253:0 0 30G 0 lvm /mnt sr0 11:0 1 792M 0 rom [root@test-centos7-node1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 46G 1.6G 45G 4% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 2.0G 135M 1.9G 7% /boot tmpfs 378M 0 378M 0% /run/user/0 /dev/mapper/test-xxx 20G 33M 20G 1% /mnt [root@test-centos7-node1 ~]#
说明：可看到lvs里的空间已经加上去，lvextend命令作用是将指定VG里的空间添加到指定的lv中，上面的例子是把VG里的所有空闲空间添加到/dev/test/xxx里，当然还有一种情况在VG还有空余的空间，我们可以用lvresize 来调整lv的大小；从上面的信息可以看到我们把新的空间加入到VG和Lv中后，df 看挂载点空间却没有增加，接下来我们通过resize2fs将文件系统同步到增大的空间。
[root@test-centos7-node1 ~]# resize2fs /dev/test/xxx resize2fs 1.42.9 (28-Dec-2013) resize2fs: Bad magic number in super-block while trying to open /dev/test/xxx Couldn't find valid filesystem superblock. [root@test-centos7-node1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 46G 1.6G 45G 4% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 2.0G 135M 1.9G 7% /boot tmpfs 378M 0 378M 0% /run/user/0 /dev/mapper/test-xxx 20G 33M 20G 1% /mnt [root@test-centos7-node1 ~]#
说明：看来用此命令不行，因为resize2fs这个命令针对ext系列的文件系统，xfs需要用 xfs_growfs来调整
[root@test-centos7-node1 ~]# xfs_growfs /dev/test/xxx
meta-data=/dev/mapper/test-xxx isize=512 agcount=4, agsize=1309696 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=5238784, 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 5238784 to 7858176
[root@test-centos7-node1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 46G 1.6G 45G 4% /
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.6M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sda1 2.0G 135M 1.9G 7% /boot
tmpfs 378M 0 378M 0% /run/user/0
/dev/mapper/test-xxx 30G 33M 30G 1% /mnt
[root@test-centos7-node1 ~]#
四、缩减LV（xfs文件系统）
1）卸载已经挂好的LV
[root@test-centos7-node1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 46G 1.6G 45G 4% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 2.0G 135M 1.9G 7% /boot tmpfs 378M 0 378M 0% /run/user/0 /dev/mapper/test-xxx 30G 33M 30G 1% /mnt [root@test-centos7-node1 ~]# umount /mnt [root@test-centos7-node1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 46G 1.6G 45G 4% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 2.0G 135M 1.9G 7% /boot tmpfs 378M 0 378M 0% /run/user/0 [root@test-centos7-node1 ~]#
2）强制进行磁盘检测
[root@test-centos7-node1 ~]# xfs_repair -n /dev/test/xxx
Phase 1 - find and verify superblock...
Phase 2 - using internal log
- zero log...
- scan filesystem freespace and inode maps...
- found root inode chunk
Phase 3 - for each AG...
- scan (but don't clear) agi unlinked lists...
- process known inodes and perform inode discovery...
- agno = 0
- agno = 1
- agno = 2
- agno = 3
- process newly discovered inodes...
Phase 4 - check for duplicate blocks...
- setting up duplicate extent list...
- check for inodes claiming duplicate blocks...
- agno = 0
- agno = 1
- agno = 2
- agno = 3
No modify flag set, skipping phase 5
Phase 6 - check inode connectivity...
- traversing filesystem ...
- traversal finished ...
- moving disconnected inodes to lost+found ...
Phase 7 - verify link counts...
No modify flag set, skipping filesystem flush and exiting.
[root@test-centos7-node1 ~]#
说明：ext系列文件系统可e2fsck命令检查
3）调整lv大小
[root@test-centos7-node1 ~]# lvreduce -L -10G /dev/test/xxx WARNING: Reducing active logical volume to <19.98 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce test/xxx"htmlcode">[root@test-centos7-node1 ~]# mount /dev/test/xxx /mnt mount: /dev/mapper/test-xxx: can't read superblock [root@test-centos7-node1 ~]#说明：做到这里发现一个问题，xfs文件系统是不支持逻辑卷缩减的，为什么呢？xfs的文件系统调整命令是xfs_growfs 这个命令只支持增大的操作。我们在调整lv大小的时候实际上是把文件系统给破坏了，要想缩减空间，就必须重新格式化后在挂载，这样一来如果原有的盘里有数据就丢了。所以xfs上做LV的缩减没有意义
[root@test-centos7-node1 ~]# mkfs.xfs /dev/test/xxx -f meta-data=/dev/test/xxx isize=512 agcount=4, agsize=1309184 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=0, sparse=0 data = bsize=4096 blocks=5236736, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal log bsize=4096 blocks=2560, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 [root@test-centos7-node1 ~]# mount /dev/test/xxx /mnt [root@test-centos7-node1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 46G 1.6G 45G 4% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 2.0G 135M 1.9G 7% /boot tmpfs 378M 0 378M 0% /run/user/0 /dev/mapper/test-xxx 20G 33M 20G 1% /mnt [root@test-centos7-node1 ~]五、缩减LV（ext系列文件系统）
1）卸载已挂载的LV
[root@test-centos7-node1 ~]# df -Th Filesystem Type Size Used Avail Use% Mounted on /dev/sda3 xfs 46G 1.6G 45G 4% / devtmpfs devtmpfs 1.9G 0 1.9G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 xfs 2.0G 135M 1.9G 7% /boot tmpfs tmpfs 378M 0 378M 0% /run/user/0 /dev/mapper/test-xxx ext4 20G 45M 19G 1% /mnt [root@test-centos7-node1 ~]# umount /mnt [root@test-centos7-node1 ~]# df -Th Filesystem Type Size Used Avail Use% Mounted on /dev/sda3 xfs 46G 1.6G 45G 4% / devtmpfs devtmpfs 1.9G 0 1.9G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 xfs 2.0G 135M 1.9G 7% /boot tmpfs tmpfs 378M 0 378M 0% /run/user/0 [root@test-centos7-node1 ~]#2）强制执行磁盘检测
[root@test-centos7-node1 ~]# e2fsck -f /dev/test/xxx 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/test/xxx: 11/1310720 files (0.0% non-contiguous), 126322/5236736 blocks [root@test-centos7-node1 ~]#说明：这一步我们在不执行的话，直接下一步它也会提示我们先做磁盘检测
3）调整文件系统大小
[root@test-centos7-node1 ~]# resize2fs /dev/test/xxx 12G resize2fs 1.42.9 (28-Dec-2013) Resizing the filesystem on /dev/test/xxx to 3145728 (4k) blocks. The filesystem on /dev/test/xxx is now 3145728 blocks long. [root@test-centos7-node1 ~]#4）调整LV的大小
[root@test-centos7-node1 ~]# lvreduce -L 12G /dev/test/xxx WARNING: Reducing active logical volume to 12.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce test/xxx"htmlcode">[root@test-centos7-node1 ~]# mount /dev/test/xxx /mnt [root@test-centos7-node1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 46G 1.6G 45G 4% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.6M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 2.0G 135M 1.9G 7% /boot tmpfs 378M 0 378M 0% /run/user/0 /dev/mapper/test-xxx 12G 41M 12G 1% /mnt [root@test-centos7-node1 ~]#以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
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