Linux磁碟管理之LVM
阿新 • • 發佈：2020-01-07
一、LVM介紹
在我們管理Linux磁碟的時候，通常會遇到這麼一種情況。在最初規劃Linux的磁碟的時候，我們給某個分區劃分了一定量的磁碟空間，使用一段時間後，發現我們規劃的磁碟空間不足了，這個時候怎麼辦？我們肯定要想辦法給擴容呀，找一塊磁碟分割槽，格式化，然後掛載，然後把資料拷貝到新加的磁碟上，然後把原有的磁碟解除安裝掉，通常我們是這樣做的。這樣一來雖然達到了擴容的目的，但是費時費力；如果第二次擴容，空間還是不夠，我們又要重複上面的步驟；如果分配的磁碟空間過大，使用了很久才發現它根本用不到那麼多空間，這個時候是不是又要調整呀，聽著就感覺很繁瑣。這時候你肯定要想有沒有那種可掛載上一塊盤，我們利用某種管理手段，可以線上的調整磁碟的空間，這樣有節約了時間，也可實現彈性管理磁碟。對，lvm就有這樣的功能。
LVM（logical volume manager）邏輯卷管理，它可以彈性的管理檔案系統的容量，LVM的工作原理是將一個或多個底層塊裝置組織成一個邏輯裝置，這個邏輯裝置可以在未來新增或移除其他的分割槽到這個邏輯裝置中，從而實現了彈性管理磁碟。
PV：物理卷（physical volume）；物理卷就是指硬碟分割槽或從邏輯上與磁碟分割槽具有同樣功能的裝置（如raid），是LVM的基本儲存邏輯塊，但和基本的物理儲存介質（如分割槽，磁碟等）比較，卻包含有與LVM相關的管理引數
VG：卷組（volume group）LVM卷組類似於非LVM系統中的物理硬碟，尤其物理卷組成，可以在卷組上建立一個或多個LVM分割槽（邏輯卷），LVM卷組由一個或多個物理卷組成
LV：邏輯卷（logical volume）LVM的邏輯卷類似非LVM系統中的硬碟分割槽，在邏輯卷之上可以建立檔案系統。
LVM就是將一些零碎的磁碟分割槽（PV）合併成一個較大的磁碟（VG），然後在根據需要對這個較大的磁碟（VG）進行劃分成不同的大小分割槽（LV），這些小的分割槽（LV）是可以動態的擴充套件和縮小的，這就是LVM的邏輯卷管理過程。所謂LVM的大磁碟就是將許多PV整合成的VG，那麼這個大磁碟最大可達到多少容量呢？我們知道在檔案系統裡面資料儲存的最小單位是塊（block），不過在LVM當中資料儲存的最小單位是PE，PE的的作用同block的作用一樣，需要注意到是LVM預設使用的PE大小是4M，而LVM的VG最多能包含65534個PE，也就是說預設LVM的VG會有4×65534M/1024M=256G，所以PE的大小決定了VG的最大容量，當然我們在建立VG的時候可指定PE大小，從而來決定VG的大小。
二、LVM實現
1）前期準備幾塊硬碟或者分割槽來模擬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 ~]#
說明：這裡是用的分割槽來模擬硬碟當作PV，這裡需要注意一點，就是我們分割槽完儲存後，可能存在不同不到問題，就是我們分割槽完用lsblk看不到分割槽，可用 partprobe來同步分割槽資訊。centos6 使用partx -a /dev/sdb來增加分割槽同步到記憶體，如果是刪除某個分割槽，就需要執行partx -d -nr # /dev/sdb 此命令表示從/dev/sdb的分割槽資訊中刪除sdb#分割槽資訊，並同步到記憶體中。這裡還需要注意一點的是我們分割槽的型別要選8e 表示Linux LVM
2）裝lvm2這個包
[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 ~]#
說明：最小化安裝系統預設系統上沒有安裝這個包的，所以我們需要把這個包裝上才可建立LVM
3）建立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 ~]#
說明：pvcreate 命令表示建立PV 後面跟硬碟或分割槽對應的裝置檔案，pvscan 命令作用是搜尋系統裡面任何具有PV屬性的磁碟，PV屬性就是通過pvcreate建立過的磁碟，pvs是檢視pv簡要情況，pvdisplay 檢視pv的詳細資訊。當然我們要移除某塊盤，讓其不具備PV屬性，可以用pvremove + 磁碟的裝置檔案路徑
[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 ~]#
說明：移除pv的前提是它沒有在任何VG裡面才可做移除，否則移除不了
4）建立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 ~]#
說明：同樣的vgcreate 表示建立VG 其用法格式是vgcreate VGNAME [option] 儲存裝置路徑 其中-s表示指定PE的大小，VGNAME表示VG的名稱，需要說明的是，指定名稱不能和系統現有的VG名稱相同；vgs檢視系統上所有VG的簡要資訊，vgscan搜尋系統上面是否有VG，vgdisplay檢視所有VG的詳細資訊，當然此例中只有一個，我們也可在後面指定檢視某個VG的詳細資訊，只需要指定其VG名稱即可；有關vg的命令有很多其中vgreduce的作用是在VG內移除PV，vgremove的作用是刪除一個VG，這兩個命令都需要在其後指定要操作的VG名稱
5）建立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? [y/n]: y Size of logical volume test/bbb changed from 3.00 GiB (384 extents) to 2.00 GiB (256 extents). Logical volume test/bbb 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----- 2.00g [root@test-centos7-node1 ~]# lvreduce -L 3G /dev/test/aaa WARNING: Reducing active logical volume to 3.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce test/aaa? [y/n]: y Size of logical volume test/aaa changed from 6.00 GiB (768 extents) to 3.00 GiB (384 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----- 3.00g bbb test -wi-a----- 2.00g [root@test-centos7-node1 ~]# lvreduce -L -1G /dev/test/aaa WARNING: Reducing active logical volume to 2.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce test/aaa? [y/n]: y Size of logical volume test/aaa changed from 3.00 GiB (384 extents) to 2.00 GiB (256 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----- 2.00g bbb test -wi-a----- 2.00g [root@test-centos7-node1 ~]# lvremove /dev/test/bbb Do you really want to remove active logical volume test/bbb? [y/n]: y Logical volume "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 ~]#
說明：lvcreate 命令作用是建立LV 其中-L表示指定LV的大小，-n表示lv的名稱 最後跟VG的名稱，表示從那個VG上建立LV；lvs 命令作用是檢視系統所有的lv簡要資訊 ；lvdisplay 檢視LV的詳細資訊，後面可以跟VG的名稱表示檢視指定VG上的所有LV的詳細資訊；lvreduce 命令作用是縮減指定LV裡的空間，如果指定的大小是負數如-3M 表示縮減3M 如果指定的是 3M 則表示縮減至3M ，這個需要注意，還有這個命令指定大小不能以類似+4M來指定；lvresize此命令的作用是調整LV的容量大小，這個命令指定調整大小+表示增加多少，-表示減少多少，若沒有+/-表示調整到指定大小，lvresize和lvreduce這兩個命令後面都是跟的lv對應裝置的路徑（其實不是真的裝置路徑，是裝置的軟連線路徑），不能指定其名稱；lvremove命令作用是刪除指定的LV,若指定的是vg名，表示刪除該VG上的所有LV，若需要刪除某個LV 需要指定其對應裝置路徑。
到此lvm就已經實現，後續就可以直接格式化，然後掛載使用了
[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? [y/n]: y
Wiping xfs signature on /dev/test/xxx.
Logical volume "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、擴容LV
1）建立PV，並將其加入到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 ~]#
說明：從上面的資訊可以看到VG的大小是19.98G 也就是兩塊PV的大小。現在我們新建立一個pv，然後加到vg裡
[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 ~]#
說明：vgextend命令作用是將指定pv加入到指定VG中，VG指定其名稱即可，pv需指定其裝置路徑
2）將新加的VG的PE加入到xxx LV裡
[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 ~]#
說明：可看到lvs裡的空間已經加上去，lvextend命令作用是將指定VG裡的空間新增到指定的lv中，上面的例子是把VG裡的所有空閒空間新增到/dev/test/xxx裡，當然還有一種情況在VG還有空餘的空間，我們可以用lvresize 來調整lv的大小；從上面的資訊可以看到我們把新的空間加入到VG和Lv中後，df 看掛載點空間卻沒有增加，接下來我們通過resize2fs將檔案系統同步到增大的空間。
[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 ~]#
說明：看來用此命令不行，因為resize2fs這個命令針對ext系列的檔案系統，xfs需要用 xfs_growfs來調整
[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、縮減LV（xfs檔案系統）
1）解除安裝已經掛好的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）強制進行磁碟檢測
[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 ~]#
說明：ext系列檔案系統可e2fsck命令檢查
3）調整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? [y/n]: y Size of logical volume test/xxx changed from <29.98 GiB (3837 extents) to <19.98 GiB (2557 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-a----- <19.98g [root@test-centos7-node1 ~]# lvdisplay --- Logical volume --- LV Path /dev/test/xxx LV Name xxx VG Name test LV UUID uhZZaz-Odd9-ibwY-2Z1Z-ZmNY-eZF7-0lXERT LV Write Access read/write LV Creation host, time test-centos7-node1, 2020-01-06 10:32:42 -0500 LV Status available # open 0 LV Size <19.98 GiB Current LE 2557 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:0 [root@test-centos7-node1 ~]#
4）掛載
[root@test-centos7-node1 ~]# mount /dev/test/xxx /mnt mount: /dev/mapper/test-xxx: can't read superblock [root@test-centos7-node1 ~]#
說明：做到這裡發現一個問題，xfs檔案系統是不支援邏輯捲縮減的，為什麼呢？xfs的檔案系統調整命令是xfs_growfs 這個命令只支援增大的操作。我們在調整lv大小的時候實際上是把檔案系統給破壞了，要想縮減空間，就必須重新格式化後在掛載，這樣一來如果原有的盤裡有資料就丟了。所以xfs上做LV的縮減沒有意義
[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、縮減LV（ext系列檔案系統）
1）解除安裝已掛載的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）強制執行磁碟檢測
[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 ~]#
說明：這一步我們在不執行的話，直接下一步它也會提示我們先做磁碟檢測
3）調整檔案系統大小
[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）調整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? [y/n]: y Size of logical volume test/xxx changed from <19.98 GiB (2557 extents) to 12.00 GiB (1536 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-a----- 12.00g [root@test-centos7-node1 ~]#
說明：這裡縮減到的空間需同文件系統的大小一致或者縮減後的空間比檔案系統調整的空間要大才行，這樣才不能損壞檔案系統，切記不能比檔案系統調整的空間還小，小了，在縮減空間的時候就破壞了檔案系統，會導致後續的掛載無法進行。
5）掛載
[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 ~]#