Linux LVM逻辑卷管理

朱雀 2023-06-02 07:45 206阅读 0赞

![CentOS-Logo][]

使用`Linux`好久了，一定会意识到一个问题，某个分区容量不够用了，想要扩容怎么办？这里就涉及到`LVM`逻辑卷的管理了，可以动态调整`Linux`分区容量。

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# LVM 概述 #

全称`Logical Volume Manager`，可以动态调整磁盘容量，提高磁盘管理灵活性。

在安装`CentOS 7`的过程中选择自动分区时，默认就是以`LVM`的方案安装的系统。

但是`/boot`分区必须独立出来，不能基于`LVM`创建。

## PV 物理卷 ##

物理卷，`Physical Volume`，是`LVM`机制的基本存储设备，通常对应一个普通分区或是整个硬盘。

创建物理卷时，会在分区或磁盘头部创建一个用于记录`LVM`属性的保留区块，并把存储空间分割成默认大小为`4MB`的基本单元（Physical Extend，PE），从而构成物理卷。

普通分区先转换分区类型为`8e`；整块硬盘，可以将所有的空间划分为一个主分区再做调整。

## VG 卷组 ##

卷组，`Volume Group`，是由一个或多个物理卷组成的一个整体。可以动态添加、移除物理卷，创建时可以指定`PE`大小。

## LV 逻辑卷 ##

逻辑卷，`Logical Volume`，建立在卷组之上，与物理卷没有直接关系。格式化后，即可挂载使用。

## 三者关系 ##

![关系图][1746090-20190824115054266-234089390.jpg]

通过以上对三者的解释可以看出，建立`LVM`的过程。首先，将普通分区或整个硬盘创建为物理卷；然后，将一个或多个物理卷创建为卷组；最后，在卷组上分割不同的数据存储空间形成逻辑卷。有了逻辑卷，就可以格式化、挂载使用了。

--------------------

# LVM 管理 #

## LVM 常用命令 ##

<table> 
 <thead> 
  <tr> 
   <th style="text-align:left;">功能</th> 
   <th style="text-align:left;">PV 管理命令</th> 
   <th style="text-align:left;">VG 管理命令</th> 
   <th style="text-align:left;">LV 管理命令</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td style="text-align:left;">Scan（扫描）</td> 
   <td style="text-align:left;">pvscan</td> 
   <td style="text-align:left;">vgscan</td> 
   <td style="text-align:left;">lvscan</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">Create（建立）</td> 
   <td style="text-align:left;">pvcreate</td> 
   <td style="text-align:left;">vgcreate</td> 
   <td style="text-align:left;">lvcreate</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">Display（显示）</td> 
   <td style="text-align:left;">pvdisplay</td> 
   <td style="text-align:left;">vgdisplay</td> 
   <td style="text-align:left;">lvdisplay</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">Remove（移除）</td> 
   <td style="text-align:left;">pvremove</td> 
   <td style="text-align:left;">vgremove</td> 
   <td style="text-align:left;">lvremove</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">Extend（扩展）</td> 
   <td style="text-align:left;">/</td> 
   <td style="text-align:left;">vgextend</td> 
   <td style="text-align:left;">lvextend</td> 
  </tr> 
  <tr> 
   <td style="text-align:left;">Reduce（减少）</td> 
   <td style="text-align:left;">/</td> 
   <td style="text-align:left;">vgreduce</td> 
   <td style="text-align:left;">lvreduce</td> 
  </tr> 
 </tbody> 
</table>

## PV 管理 ##

### pvsacn ###

*  扫描列出系统中所有的物理卷

`-e`:仅显示属于输出卷组的物理卷  
`-n`：仅显示不属于任何卷组的物理卷

[root@localhost ~]# pvscan
      PV /dev/sda2   VG centos          lvm2 [<19.00 GiB / 0    free]
      PV /dev/sdb1                      lvm2 [<20.00 GiB]
      PV /dev/sdc1                      lvm2 [<20.00 GiB]
      Total: 3 [58.99 GiB] / in use: 1 [<19.00 GiB] / in no VG: 2 [<40.00 GiB]

### pvcreate ###

*  将分区或整个硬盘转换成物理卷

[root@localhost ~]# pvcreate /dev/sd{b,c}1
      Physical volume "/dev/sdb1" successfully created.
      Physical volume "/dev/sdc1" successfully created.

### pvdisplay ###

*  显示物理卷的详细信息

[root@localhost ~]# pvdisplay
      --- Physical volume ---
      PV Name               /dev/sda2
      VG Name               centos
      PV Size               <19.00 GiB / not usable 3.00 MiB
      Allocatable           yes (but full)
      PE Size               4.00 MiB
      Total PE              4863
      Free PE               0
      Allocated PE          4863
      PV UUID               E4eovQ-CgPo-OSDK-75MO-BfD8-pGsP-BUlqip
    
      "/dev/sdb1" is a new physical volume of "<20.00 GiB"
      --- NEW Physical volume ---
      PV Name               /dev/sdb1
      VG Name
      PV Size               <20.00 GiB
      Allocatable           NO
      PE Size               0
      Total PE              0
      Free PE               0
      Allocated PE          0
      PV UUID               gR5mm3-f50o-XLTq-34GY-n6Iz-WXkQ-uMZAkJ
    
      "/dev/sdc1" is a new physical volume of "<20.00 GiB"
      --- NEW Physical volume ---
      PV Name               /dev/sdc1
      VG Name
      PV Size               <20.00 GiB
      Allocatable           NO
      PE Size               0
      Total PE              0
      Free PE               0
      Allocated PE          0
      PV UUID               O2gKxa-ONts-kyXK-zZrO-3dDg-FhtI-V6GPy9

### pvremove ###

*  删除指定的物理卷，还原成普通分区或磁盘

**TIPS**：只有不属于卷组的物理卷才可以删除还原。

[root@localhost ~]# pvremove /dev/sdd1
      Labels on physical volume "/dev/sdd1" successfully wiped.

## VG 管理 ##

### vgscan ###

*  扫描系统中已建立的`LVM`卷组

[root@localhost ~]# vgscan
      Reading volume groups from cache.
      Found volume group "class" using metadata type lvm2
      Found volume group "centos" using metadata type lvm2

### vgcreate ###

*  将一个或多个物理卷创建为一个卷组

`-l`：卷组上允许创建的最大逻辑卷数  
`-p`：卷组中允许添加的最大物理卷数  
`-s`：卷组上的物理卷的`PE`大小

[root@localhost ~]# vgcreate class /dev/sd{b,c}1
      Volume group "class" successfully created

### vgdisplay ###

*  显示系统中各卷组的详细信息

[root@localhost ~]# vgdisplay
      --- Volume group ---
      VG Name               class
      System ID
      Format                lvm2
      Metadata Areas        2
      Metadata Sequence No  1
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                0
      Open LV               0
      Max PV                0
      Cur PV                2
      Act PV                2
      VG Size               39.99 GiB
      PE Size               4.00 MiB
      Total PE              10238
      Alloc PE / Size       0 / 0
      Free  PE / Size       10238 / 39.99 GiB
      VG UUID               ZtQvGX-YOdy-U8wj-mGQs-TT1e-1PBR-dBNKAG
    
      --- Volume group ---
      VG Name               centos
      System ID
      Format                lvm2
      Metadata Areas        1
      Metadata Sequence No  3
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                2
      Open LV               2
      Max PV                0
      Cur PV                1
      Act PV                1
      VG Size               <19.00 GiB
      PE Size               4.00 MiB
      Total PE              4863
      Alloc PE / Size       4863 / <19.00 GiB
      Free  PE / Size       0 / 0
      VG UUID               bLPJGb-SQQ3-KcUb-OSdo-qaMR-9hJE-MTkc7a

### vgremove ###

*  删除指定的卷组

**TIPS**：卷组下面的逻辑卷没有被挂载使用，卷组删除时会一并删除下面的逻辑卷。

[root@localhost ~]# vgremove class
      Volume group "class" successfully removed

### vgextend ###

*  添加新的物理卷，动态扩展卷组的磁盘空间

[root@localhost ~]# vgextend class /dev/sdd1
      Volume group "class" successfully extended

### vgreduce ###

*  删除卷组中的物理卷，减少卷组容量，

`-a`：如果命令行中没有指定要删除的物理卷，则删除所有的空物理卷。（all）

**TIPS**：删除啊前确保对应的物理卷没有在使用，就是下面没有逻辑卷，否则删除不了。

[root@localhost ~]# vgreduce class /dev/sdd1
      Removed "/dev/sdd1" from volume group "class"

[root@localhost ~]# vgreduce -a class
      Physical volume "/dev/sdb1" still in use
      Physical volume "/dev/sdc1" still in use
      Removed "/dev/sdd1" from volume group "class"

## LV 管理 ##

### lvscan ###

*  扫描系统中已建立的`LVM`逻辑卷

[root@localhost ~]# lvscan
      ACTIVE            '/dev/class/stu01' [25.00 GiB] inherit
      ACTIVE            '/dev/class/stu02' [14.99 GiB] inherit
      ACTIVE            '/dev/centos/swap' [2.00 GiB] inherit
      ACTIVE            '/dev/centos/root' [<17.00 GiB] inherit

### lvcreate ###

*  从指定的卷组中分割空间，创建新的逻辑卷

`-L`：指定逻辑卷的大小，单位为`KMGT`  
`-l`：指定百分比创建，如`50%vg`卷组的一半空间、`100%free`所有剩下的。  
`-n`：指定逻辑卷的名称

[root@localhost ~]# lvcreate -L 15G -n stu01 class
      Logical volume "stu01" created.

[root@localhost ~]# lvcreate -l 100%free -n stu02 class
      Logical volume "stu02" created.

### lvdisplay ###

*  显示逻辑卷的详细信息

[root@localhost ~]# lvdisplay
      --- Logical volume ---
      LV Path                /dev/class/stu01
      LV Name                stu01
      VG Name                class
      LV UUID                XUP7dq-IM9f-PdKk-XpDH-J1hx-kkuB-cOu3Qx
      LV Write Access        read/write
      LV Creation host, time localhost.localdomain, 2019-08-24 09:42:35 +0800
      LV Status              available
      # open                 0
      LV Size                25.00 GiB
      Current LE             6400
      Segments               2
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     8192
      Block device           253:2
    
      --- Logical volume ---
      LV Path                /dev/class/stu02
      LV Name                stu02
      VG Name                class
      LV UUID                P7iMC1-X0oT-6TCH-vLYj-HW2j-6QMu-rS7Jyp
      LV Write Access        read/write
      LV Creation host, time localhost.localdomain, 2019-08-24 09:59:30 +0800
      LV Status              available
      # open                 0
      LV Size                14.99 GiB
      Current LE             3838
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     8192
      Block device           253:3
    
      --- Logical volume ---
      LV Path                /dev/centos/swap
      LV Name                swap
      VG Name                centos
      LV UUID                NXiaXT-T6yv-ktM2-plyS-j6Hg-hkvu-1JQ2eL
      LV Write Access        read/write
      LV Creation host, time localhost, 2019-08-16 17:12:19 +0800
      LV Status              available
      # open                 2
      LV Size                2.00 GiB
      Current LE             512
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     8192
      Block device           253:1
    
      --- Logical volume ---
      LV Path                /dev/centos/root
      LV Name                root
      VG Name                centos
      LV UUID                7FnsfT-B8xi-3vgu-8N0k-nzNn-8Rra-eoE4iC
      LV Write Access        read/write
      LV Creation host, time localhost, 2019-08-16 17:12:19 +0800
      LV Status              available
      # open                 1
      LV Size                <17.00 GiB
      Current LE             4351
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     8192
      Block device           253:0

### lvremove ###

*  删除指定的逻辑卷

**TIPS**：备份数据，解挂载，删除。

[root@localhost ~]# umount /mnt/stu02/
    [root@localhost ~]# lvremove /dev/class/stu02

### lvextend ###

*  动态扩展`LVM`逻辑卷的空间大小

`-L`：指定扩展逻辑卷的大小，单位为`KMGT`  
`-l`：指定百分比扩建，如`100%free`所有剩下的。

[root@localhost ~]# lvextend -L +8G /dev/class/stu01
    [root@localhost ~]# lvextend -L +8G /dev/class/stu02

**TIPS**：已挂载，使用在线调整大小，`xfs`使用`xfs_growfs`，`ext4`使用`resize2fs`。

[root@localhost ~]# xfs_growfs /dev/class/stu01
    [root@localhost ~]# resize2fs /dev/class/stu02

### lvreduce ###

*  减少`LVM`逻辑卷的空间大小，

`-L`：指定逻辑卷的大小，单位为`KMGT`

**TIPS**：对于`xfs`文件系统，备份数据，解挂载，减少空间，强制格式化，重新挂载。需要注意`xfs`文件系统只能扩大，不能缩小，非要缩小的话，只有缩小后并强制格式化，但这么做数据就丢失了。

[root@localhost ~]# umount /mnt/stu01/
    [root@localhost ~]# lvreduce -L -10G /dev/class/stu01
    [root@localhost ~]# mkfs.xfs -f /dev/class/stu01
    [root@localhost ~]# mount -a
    [root@localhost ~]# df -hT

**TIPS**：对于`ext4`这类文件系统，备份数据，解挂载，`e2fsck -f`检查文件系统完整性，`resize2fs`设置文件系统大小，`lvreduce`设置逻辑卷大小，重新挂载。

[root@localhost ~]# umount /mnt/stu02/
    [root@localhost ~]# e2fsck -f /dev/class/stu02
    [root@localhost ~]# resize2fs /dev/class/stu02 10G
    [root@localhost ~]# lvreduce -L 10G /dev/class/stu02
    [root@localhost ~]# mount -a
    [root@localhost ~]# df -hT

--------------------

# LVM 实验 #

## 创建 LVM 逻辑卷 ##

1.添加两块`20G`的磁盘，重启机器，并对其进行分区，全部空间分为一个主分区，类型改为`Linux LVM`，ID为`8e`。分区过程省略，不清楚可参考[上一篇博客][Link 1]。

[root@localhost ~]# fdisk -l /dev/sd{b,c} | grep -i "linux lvm"
    /dev/sdb1            2048    41943039    20970496   8e  Linux LVM
    /dev/sdc1            2048    41943039    20970496   8e  Linux LVM

2.将`/dev/sdb1`、`/dev/sdc1`转换为物理卷。

[root@localhost ~]# pvcreate /dev/sd{b,c}1
      Physical volume "/dev/sdb1" successfully created.
      Physical volume "/dev/sdc1" successfully created.

3.创建名称为`class`的卷组，并将`sdb1`和`sdc1`添加进卷组。

[root@localhost ~]# vgcreate class /dev/sd{b,c}1
      Volume group "class" successfully created

4.划分大小为`15G`，名称为`stu01`的逻辑卷，然后再扩容`10G`；剩下的空间创建名称为`stu02`的逻辑卷。

[root@localhost ~]# lvcreate -L 15G -n stu01 class
      Logical volume "stu01" created.
    [root@localhost ~]# lvextend -L +10G /dev/class/stu01
      Size of logical volume class/stu01 changed from 15.00 GiB (3840 extents) to 25.00 GiB (6400 extents).
      Logical volume class/stu01 successfully resized.

[root@localhost ~]# lvcreate -l 100%free -n stu02 class
      Logical volume "stu02" created.

5.格式化逻辑卷，`stu01`为`xfs`，`stu02`为`ext4`，设置自动挂载，挂载后就可以使用了。

[root@localhost ~]# mkfs.xfs /dev/class/stu01
    meta-data=/dev/class/stu01       isize=512    agcount=4, agsize=1638400 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0, sparse=0
    data     =                       bsize=4096   blocks=6553600, imaxpct=25
             =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
    log      =internal log           bsize=4096   blocks=3200, version=2
             =                       sectsz=512   sunit=0 blks, lazy-count=1
    realtime =none                   extsz=4096   blocks=0, rtextents=0

[root@localhost ~]# mkfs.ext4 /dev/class/stu02
    mke2fs 1.42.9 (28-Dec-2013)
    Filesystem label=
    OS type: Linux
    Block size=4096 (log=2)
    Fragment size=4096 (log=2)
    Stride=0 blocks, Stripe width=0 blocks
    983040 inodes, 3930112 blocks
    196505 blocks (5.00%) reserved for the super user
    First data block=0
    Maximum filesystem blocks=2151677952
    120 block groups
    32768 blocks per group, 32768 fragments per group
    8192 inodes per group
    Superblock backups stored on blocks:
            32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208
    
    Allocating group tables: done
    Writing inode tables: done
    Creating journal (32768 blocks): done
    Writing superblocks and filesystem accounting information: done

[root@localhost ~]# mkdir /mnt/stu0{1,2}
    [root@localhost ~]# vim /etc/fstab
    //最后面添加下面两行内容
    /dev/class/stu01        /mnt/stu01      xfs     defaults        0 0
    /dev/class/stu02        /mnt/stu02      ext4    defaults        0 0

[root@localhost ~]# mount -a
    [root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G  927M   17G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  904M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
    /dev/mapper/class-stu01 xfs        25G   33M   25G   1% /mnt/stu01
    /dev/mapper/class-stu02 ext4       15G   41M   14G   1% /mnt/stu02

## 扩容 LVM 逻辑卷 ##

1.再添加一块20G的磁盘，重启机器，并对其进行分区，全部空间分为一个主分区，类型改为`Linux LVM`，ID为`8e`。

[root@localhost ~]# fdisk -l /dev/sd{b..d} | grep -i "linux lvm"
    /dev/sdb1            2048    41943039    20970496   8e  Linux LVM
    /dev/sdc1            2048    41943039    20970496   8e  Linux LVM
    /dev/sdd1            2048    41943039    20970496   8e  Linux LVM

2.将`/dev/sdd1`转换为物理卷。

[root@localhost ~]# pvcreate /dev/sdd1
      Physical volume "/dev/sdd1" successfully created.

3.若是卷组剩余空间不够，就要先对`class`卷组进行扩容。

[root@localhost ~]# vgdisplay class
      --- Volume group ---
      VG Name               class
      System ID
      Format                lvm2
      Metadata Areas        2
      Metadata Sequence No  6
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                2
      Open LV               2
      Max PV                0
      Cur PV                2
      Act PV                2
      VG Size               39.99 GiB
      PE Size               4.00 MiB
      Total PE              10238
      Alloc PE / Size       10238 / 39.99 GiB
      Free  PE / Size       0 / 0
      VG UUID               iB1h9h-2uQa-rD7o-GBVK-pOCA-ek2c-TXieLr

[root@localhost ~]# vgextend class /dev/sdd1
      Volume group "class" successfully extended

[root@localhost ~]# vgdisplay class
      --- Volume group ---
      VG Name               class
      System ID
      Format                lvm2
      Metadata Areas        3
      Metadata Sequence No  7
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                2
      Open LV               2
      Max PV                0
      Cur PV                3
      Act PV                3
      VG Size               <59.99 GiB
      PE Size               4.00 MiB
      Total PE              15357
      Alloc PE / Size       10238 / 39.99 GiB
      Free  PE / Size       5119 / <20.00 GiB
      VG UUID               iB1h9h-2uQa-rD7o-GBVK-pOCA-ek2c-TXieLr

4.对`stu01`和`stu02`都扩容`8G`，分别使用`xfs_growfs`和`resize2fs`在线调整大小。

[root@localhost ~]# lvextend -L +8G /dev/class/stu01
      Size of logical volume class/stu01 changed from 25.00 GiB (6400 extents) to 33.00 GiB (8448 extents).
      Logical volume class/stu01 successfully resized.

[root@localhost ~]# lvextend -L +8G /dev/class/stu02
      Size of logical volume class/stu02 changed from 14.99 GiB (3838 extents) to 22.99 GiB (5886 extents).
      Logical volume class/stu02 successfully resized.

[root@localhost ~]# xfs_growfs /dev/class/stu01
    meta-data=/dev/mapper/class-stu01 isize=512    agcount=4, agsize=1638400 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0 spinodes=0
    data     =                       bsize=4096   blocks=6553600, imaxpct=25
             =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
    log      =internal               bsize=4096   blocks=3200, version=2
             =                       sectsz=512   sunit=0 blks, lazy-count=1
    realtime =none                   extsz=4096   blocks=0, rtextents=0
    data blocks changed from 6553600 to 8650752

[root@localhost ~]# resize2fs /dev/class/stu02
    resize2fs 1.42.9 (28-Dec-2013)
    Filesystem at /dev/class/stu02 is mounted on /mnt/stu02; on-line resizing required
    old_desc_blocks = 2, new_desc_blocks = 3
    The filesystem on /dev/class/stu02 is now 6027264 blocks long.

[root@localhost ~]# df -hT
    Filesystem              Type      Size  Used Avail Use% Mounted on
    /dev/mapper/centos-root xfs        17G  927M   17G   6% /
    devtmpfs                devtmpfs  901M     0  901M   0% /dev
    tmpfs                   tmpfs     912M     0  912M   0% /dev/shm
    tmpfs                   tmpfs     912M  8.7M  903M   1% /run
    tmpfs                   tmpfs     912M     0  912M   0% /sys/fs/cgroup
    /dev/sda1               xfs      1014M  143M  872M  15% /boot
    /dev/mapper/class-stu01 xfs        33G   33M   33G   1% /mnt/stu01
    /dev/mapper/class-stu02 ext4       23G   44M   22G   1% /mnt/stu02
    tmpfs                   tmpfs     183M     0  183M   0% /run/user/0

## 收缩 LVM 逻辑卷 ##

关于收缩 LVM 逻辑卷，可以参考上面的命令`lvreduce`。这会涉及到数据安全性问题，谨慎使用。

--------------------

# 总结 #

内容不多，但是还要实际操作才能了解。就是三步走，创建物理卷，创建卷组，创建逻辑卷，然后格式化并挂载使用。扩容的话，没有挂载使用，就正常扩，然后格式化挂载，已经挂载使用了，扩容后在线调整生效。还有下一篇关于磁盘配额。

转载于:https://www.cnblogs.com/llife/p/11404135.html

[CentOS-Logo]: /images/20230601/ecc7d7c41e3741958ae034ea43e6c4b3.png
[1746090-20190824115054266-234089390.jpg]: /images/20230601/582f8d3e96f444d59a46590cf5f39764.png
[Link 1]: https://www.cnblogs.com/llife/p/11388135.html