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 ~]# lsblkNAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTsda      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/sdbWelcome 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 tableBuilding a new DOS disklabel with disk identifier 0x6180123f.Command (m for help): pDisk /dev/sdb: 53.7 GB, 53687091200 bytes, 104857600 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk identifier: 0x6180123f   Device Boot      Start         End      Blocks   Id  SystemCommand (m for help): nPartition type:   p   primary (0 primary, 0 extended, 4 free)   e   extendedSelect (default p): pPartition number (1-4, default 1): First sector (2048-104857599, default 2048): Using default value 2048Last sector, +sectors or +size{K,M,G} (2048-104857599, default 104857599): +10GPartition 1 of type Linux and of size 10 GiB is setCommand (m for help): pDisk /dev/sdb: 53.7 GB, 53687091200 bytes, 104857600 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk identifier: 0x6180123f   Device Boot      Start         End      Blocks   Id  System/dev/sdb1            2048    20973567    10485760   83  LinuxCommand (m for help): tSelected partition 1Hex code (type L to list all codes): 8eChanged type of partition 'Linux' to 'Linux LVM'Command (m for help): nPartition type:   p   primary (1 primary, 0 extended, 3 free)   e   extendedSelect (default p): pPartition number (2-4, default 2): First sector (20973568-104857599, default 20973568): Using default value 20973568Last sector, +sectors or +size{K,M,G} (20973568-104857599, default 104857599): +10GPartition 2 of type Linux and of size 10 GiB is setCommand (m for help): tPartition number (1,2, default 2): Hex code (type L to list all codes): 8eChanged type of partition 'Linux' to 'Linux LVM'Command (m for help): nPartition type:   p   primary (2 primary, 0 extended, 2 free)   e   extendedSelect (default p): pPartition number (3,4, default 3): First sector (41945088-104857599, default 41945088): Using default value 41945088Last sector, +sectors or +size{K,M,G} (41945088-104857599, default 104857599): +10GPartition 3 of type Linux and of size 10 GiB is setCommand (m for help): tPartition 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): pDisk /dev/sdb: 53.7 GB, 53687091200 bytes, 104857600 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk 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 LVMCommand (m for help): wThe partition table has been altered!Calling ioctl() to re-read partition table.Syncing disks.[root@test-centos7-node1 ~]# lsblkNAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTsda      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: fastestmirrorLoading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.comAvailable PackagesName        : lvm2Arch        : x86_64Epoch       : 7Version     : 2.02.185Release     : 2.el7_7.2Size        : 1.3 MRepo        : updates/7/x86_64Summary     : Userland logical volume management toolsURL         : http://sources.redhat.com/lvm2License     : GPLv2Description : 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 -yLoaded plugins: fastestmirrorLoading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.comResolving 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 ResolutionDependencies Resolved============================================================================================================================ Package                                   Arch               Version                             Repository           Size============================================================================================================================Installing: lvm2                                      x86_64             7:2.02.185-2.el7_7.2                updates             1.3 MInstalling 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 MUpdating 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 kTransaction Summary============================================================================================================================Install  1 Package  (+4 Dependent packages)Upgrade             ( 2 Dependent packages)Total download size: 3.8 MDownloading 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 checkRunning transaction testTransaction test succeededRunning 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? [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/bbbDo 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 ~]#

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 testWARNING: 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=0data     =                       bsize=4096   blocks=5238784, imaxpct=25         =                       sunit=0      swidth=0 blksnaming   =version 2              bsize=4096   ascii-ci=0 ftype=1log      =internal log           bsize=4096   blocks=2560, version=2         =                       sectsz=512   sunit=0 blks, lazy-count=1realtime =none                   extsz=4096   blocks=0, rtextents=0[root@test-centos7-node1 ~]# lsblkNAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTsda            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 -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 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 ~]# lsblkNAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTsda            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  /mntsr0           11:0    1  792M  0 rom  [root@test-centos7-node1 ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 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/xxxCouldn't find valid filesystem superblock.[root@test-centos7-node1 ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 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=0data     =                       bsize=4096   blocks=5238784, imaxpct=25         =                       sunit=0      swidth=0 blksnaming   =version 2              bsize=4096   ascii-ci=0 ftype=1log      =internal               bsize=4096   blocks=2560, version=2         =                       sectsz=512   sunit=0 blks, lazy-count=1realtime =none                   extsz=4096   blocks=0, rtextents=0data blocks changed from 5238784 to 7858176[root@test-centos7-node1 ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 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 -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 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 -hFilesystem      Size  Used Avail Use% Mounted on/dev/sda3        46G  1.6G   45G   4% /devtmpfs        1.9G     0  1.9G   0% /devtmpfs           1.9G     0  1.9G   0% /dev/shmtmpfs           1.9G  8.6M  1.9G   1% /runtmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1       2.0G  135M  1.9G   7% /boottmpfs           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 chunkPhase 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 = 3No modify flag set, skipping phase 5Phase 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? [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)挂载

[root@test-centos7-node1 ~]# mount /dev/test/xxx /mntmount: /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 -fmeta-data=/dev/test/xxx          isize=512    agcount=4, agsize=1309184 blks         =                       sectsz=512   attr=2, projid32bit=1         =                       crc=1        finobt=0, sparse=0data     =                       bsize=4096   blocks=5236736, imaxpct=25         =                       sunit=0      swidth=0 blksnaming   =version 2              bsize=4096   ascii-ci=0 ftype=1log      =internal log           bsize=4096   blocks=2560, version=2         =                       sectsz=512   sunit=0 blks, lazy-count=1realtime =none                   extsz=4096   blocks=0, rtextents=0[root@test-centos7-node1 ~]# mount  /dev/test/xxx  /mnt[root@test-centos7-node1 ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 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 -ThFilesystem           Type      Size  Used Avail Use% Mounted on/dev/sda3            xfs        46G  1.6G   45G   4% /devtmpfs             devtmpfs  1.9G     0  1.9G   0% /devtmpfs                tmpfs     1.9G     0  1.9G   0% /dev/shmtmpfs                tmpfs     1.9G  8.6M  1.9G   1% /runtmpfs                tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1            xfs       2.0G  135M  1.9G   7% /boottmpfs                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% /devtmpfs          tmpfs     1.9G     0  1.9G   0% /dev/shmtmpfs          tmpfs     1.9G  8.6M  1.9G   1% /runtmpfs          tmpfs     1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1      xfs       2.0G  135M  1.9G   7% /boottmpfs          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 sizesPass 2: Checking directory structurePass 3: Checking directory connectivityPass 4: Checking reference countsPass 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 12Gresize2fs 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? [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 ~]#

说明：这里缩减到的空间需同文件系统的大小一致或者缩减后的空间比文件系统调整的空间要大才行，这样才不能损坏文件系统，切记不能比文件系统调整的空间还小，小了，在缩减空间的时候就破坏了文件系统，会导致后续的挂载无法进行。

5)挂载

[root@test-centos7-node1 ~]# mount /dev/test/xxx /mnt[root@test-centos7-node1 ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda3              46G  1.6G   45G   4% /devtmpfs              1.9G     0  1.9G   0% /devtmpfs                 1.9G     0  1.9G   0% /dev/shmtmpfs                 1.9G  8.6M  1.9G   1% /runtmpfs                 1.9G     0  1.9G   0% /sys/fs/cgroup/dev/sda1             2.0G  135M  1.9G   7% /boottmpfs                 378M     0  378M   0% /run/user/0/dev/mapper/test-xxx   12G   41M   12G   1% /mnt[root@test-centos7-node1 ~]#