【Linux】记录人生第一次LVM操作全过程：新建LV、扩容LV

痛定思痛。 2023-10-05 16:18 4阅读 0赞

本篇文章主要给需要对指定文件目录进行扩容或者创建LV的小白提供参考。

最近测试环境的RocketMQ总是报磁盘不足，测试环境的机器是我们自己玩的，运维不管，业务团队每次找我解决，我就使用du -h --max-depth=1尝试着删除一些无用的大文件，但是治标不治本，于是，不懂运维的开发，不是好的产品，我决定来一次扩容！

经过一阵子在知识的海洋里扑腾之后，初步了解了LVM(Logical Volume Manager)相关的一些知识：磁盘(Disk)、分区(Partition)、物理卷PV(Physical Volume)、卷组VG(Volume Group)、逻辑卷LV(Logical Volume)等等，详细的含义请自行查找专业的资料。

### 扩容LV ###

最后挂载到文件目录的存储其实是LV，所以对LV进行扩容即可，步骤大概是：

1、基于磁盘剩余的空间创建分区；

2、根据创建好的分区，创建PV；

3、将PV扩展到目标VG；

4、扩展VG中的LV；

演示如下：

先看看各个文件目录容量的使用情况：可以看到经常报磁盘满的目录neworiental使用了81%，接下来就是针对该目录进行扩容。

[root@XXGL-T-TJSYZ-REDIS-01 ~]# df -lh
    Filesystem                   Size  Used Avail Use% Mounted on
    devtmpfs                      16G     0   16G   0% /dev
    tmpfs                         16G  113M   16G   1% /dev/shm
    tmpfs                         16G  1.6G   15G  10% /run
    tmpfs                         16G     0   16G   0% /sys/fs/cgroup
    /dev/mapper/vg_root-lvall     31G   12G   19G  39% /
    /dev/mapper/vg_root-lvusr     10G  6.8G  3.3G  68% /usr
    /dev/mapper/vg_root-lvtmp    5.0G   43M  5.0G   1% /tmp
    /dev/mapper/vg_new-lvnew      60G   48G   12G  81% /neworiental
    /dev/mapper/vg_new-lvbackup  5.0G   33M  5.0G   1% /backup
    /dev/mapper/vg_root-lvvar    5.0G  2.2G  2.9G  43% /var
    /dev/sda1                    497M  219M  279M  44% /boot
    tmpfs                        3.2G     0  3.2G   0% /run/user/0
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

查看系统中的磁盘使用情况

[root@XXGL-T-TJSYZ-REDIS-01 ~]# fdisk -l
    
    Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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: 0x00011297
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1   *        2048     1026047      512000   83  Linux
    /dev/sda2         1026048    74434559    36704256   8e  Linux LVM
    /dev/sda3        74434560   128960511    27262976   8e  Linux LVM
    /dev/sda4       128960512   209715199    40377344    5  Extended
    /dev/sda5       128962560   170905599    20971520   8e  Linux LVM
    /dev/sda6       170907648   209715199    19403776   8e  Linux LVM
    
    Disk /dev/mapper/vg_root-lvall: 33.2 GB, 33181138944 bytes, 64806912 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    
    
    Disk /dev/mapper/vg_root-lvusr: 10.7 GB, 10737418240 bytes, 20971520 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    
    
    Disk /dev/mapper/vg_root-lvvar: 5368 MB, 5368709120 bytes, 10485760 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    
    
    Disk /dev/mapper/vg_root-lvtmp: 5368 MB, 5368709120 bytes, 10485760 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    
    Disk /dev/sdb: 107.4 GB, 107374182400 bytes, 209715200 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: 0xa646c2a2
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sdb1            2048    41945087    20971520   8e  Linux LVM
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

看这条信息：Disk /dev/sdb: 107.4 GB, 107374182400 bytes, 209715200 sectors，总共107.4G，该磁盘已经有了一个pv：/dev/sdb1，我们继续在该磁盘上建立分区。（sectors是扇面，一个扇面大小是 1\* 512 = 512个字节）

[root@XXGL-T-TJSYZ-REDIS-01 ~]# 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.
    
    Command (m for help): m //先看看帮助信息
    Command action
       a   toggle a bootable flag
       b   edit bsd disklabel
       c   toggle the dos compatibility flag
       d   delete a partition
       g   create a new empty GPT partition table
       G   create an IRIX (SGI) partition table
       l   list known partition types
       m   print this menu
       n   add a new partition //正是我要使用的
       o   create a new empty DOS partition table
       p   print the partition table
       q   quit without saving changes
       s   create a new empty Sun disklabel
       t   change a partition's system id
       u   change display/entry units
       v   verify the partition table
       w   write table to disk and exit
       x   extra functionality (experts only)
    
    Command (m for help): n //新建分区
    Partition type:
       p   primary (1 primary, 0 extended, 3 free)
       e   extended
    Select (default p): p //选择默认的p
    Partition number (2-4, default 2): 2//定义分区编号，因为分区1已经使用了，所以默认从2开始
    First sector (41945088-209715199, default 41945088): //使用默认的 直接回车
    Using default value 41945088
    Last sector, +sectors or +size{K,M,G} (41945088-209715199, default 209715199): +40G //定义分区的大小，别忘了加号
    Partition 2 of type Linux and of size 40 GiB is set //提示分区2已设置
    
    Command (m for help): t //创建完之后，还需要对分区进行修改
    Partition number (1,2, default 2): 2 //选择刚刚创建的2
    Hex code (type L to list all codes): 8e //修改分区的类型为8e，对应Linux LVM类型
    Changed type of partition 'Linux' to 'Linux LVM'
    
    Command (m for help): w //保存
    The partition table has been altered!
    
    Calling ioctl() to re-read partition table.
    
    WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
    The kernel still uses the old table. The new table will be used at
    the next reboot or after you run partprobe(8) or kpartx(8)
    Syncing disks.
    [root@XXGL-T-TJSYZ-REDIS-01 ~]# partprobe //刷新分区表
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

经过上边的操作，使用fdisk -l 可以看到刚刚创建的分区信息：/dev/sdb2

[root@XXGL-T-TJSYZ-REDIS-01 /]# fdisk -l
    ...
    ...
    Disk /dev/sdb: 107.4 GB, 107374182400 bytes, 209715200 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: 0xa646c2a2
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sdb1            2048    41945087    20971520   8e  Linux LVM
    /dev/sdb2        41945088   125831167    41943040   8e  Linux LVM

/dev/sdb2就是刚刚创建的分区，接下来创建PV

[root@XXGL-T-TJSYZ-REDIS-01 ~]# pvcreate  /dev/sdb2 //创建pv：pvcreate 分区名
      Physical volume "/dev/sdb2" successfully created.
    [root@XXGL-T-TJSYZ-REDIS-01 ~]# pvdisplay //显示当前的所有pv
      --- Physical volume ---
      PV Name               /dev/sda2
      VG Name               vg_root
      PV Size               35.00 GiB / not usable 4.00 MiB
      Allocatable           yes (but full)
      PE Size               4.00 MiB
      Total PE              8960
      Free PE               0
      Allocated PE          8960
      PV UUID               yC67Cm-Hvxr-aXde-ovxA-1qME-UEIa-hmkzgq
       
      --- Physical volume ---
      PV Name               /dev/sdb1
      VG Name               vg_root
      PV Size               20.00 GiB / not usable 4.00 MiB
      Allocatable           yes 
      PE Size               4.00 MiB
      Total PE              5119
      Free PE               24
      Allocated PE          5095
      PV UUID               GSGymp-CDjX-wkra-1kCn-b3fj-upgx-PQHf4X
       
      --- Physical volume ---
      PV Name               /dev/sda3
      VG Name               vg_new
      PV Size               <26.00 GiB / not usable 3.00 MiB
      Allocatable           yes (but full)
      PE Size               4.00 MiB
      Total PE              6655
      Free PE               0
      Allocated PE          6655
      PV UUID               NTfuir-ISnX-Z3n0-EW4K-lVO8-dW6W-92Qrsx
       
      --- Physical volume ---
      PV Name               /dev/sda5
      VG Name               vg_new
      PV Size               20.00 GiB / not usable 4.00 MiB
      Allocatable           yes (but full)
      PE Size               4.00 MiB
      Total PE              5119
      Free PE               0
      Allocated PE          5119
      PV UUID               KnrJ1f-FyYN-ThU6-BqTK-VX17-sNbE-gmbzDr
       
      --- Physical volume ---
      PV Name               /dev/sda6
      VG Name               vg_new
      PV Size               18.50 GiB / not usable 0   
      Allocatable           yes 
      PE Size               4.00 MiB
      Total PE              4737
      Free PE               24
      Allocated PE          4713
      PV UUID               Tc7uLW-dDHC-bELB-Rvlf-GNeQ-w26P-c0w1OK
       
      "/dev/sdb2" is a new physical volume of "40.00 GiB"
      --- NEW Physical volume ---
      PV Name               /dev/sdb2
      VG Name               
      PV Size               40.00 GiB
      Allocatable           NO
      PE Size               0   
      Total PE              0
      Free PE               0
      Allocated PE          0
      PV UUID               3CMhqd-SZr6-V9bQ-ofKV-C3TC-DUhP-9qB8Wv
       
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

看上面的最后一条NEW Physical volume，就是新创建好的PV

这一步如果出现这个错误，执行一下命令：partprobe即可（问题所在： 内核没有成功同步分区信息，所有才需要使用"partprobe"命令来手动同步）

[root@mq03 ~]# pvcreate /dev/sdb2
    File descriptor 3 (socket:[421941890]) leaked on pvcreate invocation. Parent PID 197714: -bash
      Device /dev/sdb2 not found.

接下来扩展VG：如果不知道你的目录对应的LV属于哪个VG，使用df -h 目录名查看：

[root@XXGL-T-TJSYZ-REDIS-01 /]# df -h /neworiental/
    Filesystem                Size  Used Avail Use% Mounted on
    /dev/mapper/vg_new-lvnew  100G   51G   50G  51% /neworiental
    [root@XXGL-T-TJSYZ-REDIS-01 /]#

看该目录的Filesystem对应的信息：/dev/mapper/vg\_new-lvnew，后面的vg\_new-lvnew命名规则是：VG名称-LV名称，所以定位到neworiental目录对应的VG是vg\_new

[root@XXGL-T-TJSYZ-REDIS-03 ~]# vgs //查看当前的所有vg
      VG      #PV #LV #SN Attr   VSize   VFree 
      vg_new    1   2   0 wz--n-  64.50g  4.00m
      vg_root   2   5   0 wz--n- <55.00g 96.00m
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# vgdisplay -v vg_new //指定vg查看信息
      --- Volume group ---
      VG Name               vg_new
      System ID             
      Format                lvm2
      Metadata Areas        1
      Metadata Sequence No  5
      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               64.50 GiB
      PE Size               4.00 MiB
      Total PE              16513
      Alloc PE / Size       16512 / 64.50 GiB
      Free  PE / Size       1 / 4.00 MiB
      VG UUID               UOiRzY-x5yr-4ZCn-JtWw-hNIg-SgSc-etx1kO
       
      --- Logical volume ---
      LV Path                /dev/vg_new/lvnew
      LV Name                lvnew
      VG Name                vg_new
      LV UUID                0M2v3T-LHZs-8lkR-ocbC-v0bs-eRz2-BjRsf2
      LV Write Access        read/write
      LV Creation host, time localhost.localdomain, 2017-06-15 10:23:32 +0800
      LV Status              available
      # open                 1
      LV Size                59.50 GiB
      Current LE             15232
      Segments               2
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     256
      Block device           253:3
       
      --- Logical volume ---
      LV Path                /dev/vg_new/lvbackup
      LV Name                lvbackup
      VG Name                vg_new
      LV UUID                Z0QEKs-Io1j-yqOw-Uipq-IDHL-zRNH-DlElyp
      LV Write Access        read/write
      LV Creation host, time localhost.localdomain, 2017-06-15 10:23:32 +0800
      LV Status              available
      # open                 1
      LV Size                5.00 GiB
      Current LE             1280
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     256
      Block device           253:4
       
      --- Physical volumes ---
      PV Name               /dev/sda3     
      PV UUID               NTfuir-ISnX-Z3n0-EW4K-lVO8-dW6W-92Qrsx
      PV Status             allocatable
      Total PE / Free PE    16513 / 1

可以看到目录neworiental对应的VG：vg\_new的大小为64.50 GiB；对应的LV：lvnew的大小为59.5G，路径(LV Path)为：/dev/vg\_new/lvnew

下面开始扩容：

[root@XXGL-T-TJSYZ-REDIS-03 ~]# vgextend vg_new /dev/sdb2 //扩容VG：vgextend VG名称 PV名称
      Volume group "vg_new" successfully extended

提示扩容成功，下面看看VG信息

[root@XXGL-T-TJSYZ-REDIS-03 ~]# vgdisplay -v vg_new 
      --- Volume group ---
      VG Name               vg_new
      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               104.50 GiB
      PE Size               4.00 MiB
      Total PE              26752
      Alloc PE / Size       16512 / 64.50 GiB
      Free  PE / Size       10240 / 40.00 GiB
      VG UUID               UOiRzY-x5yr-4ZCn-JtWw-hNIg-SgSc-etx1kO

可以看到VG Size 104.50 GiB，已经加了40G，下面扩LV：lvextend -L +扩容大小 LV路径

[root@XXGL-T-TJSYZ-REDIS-03 ~]# lvextend -L +20G /dev/vg_new/lvnew //扩容LV
      Size of logical volume vg_new/lvnew changed from 59.50 GiB (15232 extents) to 79.50 GiB (20352 extents).
      Logical volume vg_new/lvnew successfully resized.
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# 
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# xfs_growfs /dev/vg_new/lvnew //这一步不要忘记，同步文件系统
    meta-data=/dev/mapper/vg_new-lvnew isize=512    agcount=12, agsize=1310720 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0 spinodes=0
    data     =                       bsize=4096   blocks=15597568, 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 15597568 to 20840448
    [root@XXGL-T-TJSYZ-REDIS-03 ~]#

**注意：xfs\_growfs是针对xfs类型的，如果是ext4，需要使用resize2fs命令，使用df -Th可以看文件系统类型**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzE0ODQwNTU5_size_16_color_FFFFFF_t_70_pic_center]

这样，LV就扩容成功了（本来是想扩40G的，操作失误了，不过无所谓，后面还可以再扩LV）

看看扩容后的文件目录信息：已经变成80G了

[root@XXGL-T-TJSYZ-REDIS-03 ~]# df -lh
    Filesystem                   Size  Used Avail Use% Mounted on
    devtmpfs                      16G     0   16G   0% /dev
    tmpfs                         16G  202M   16G   2% /dev/shm
    tmpfs                         16G  1.6G   15G  10% /run
    tmpfs                         16G     0   16G   0% /sys/fs/cgroup
    /dev/mapper/vg_root-lvall     31G   22G  9.5G  70% /
    /dev/mapper/vg_root-lvusr     10G  7.1G  3.0G  71% /usr
    /dev/sda1                    497M  219M  279M  44% /boot
    /dev/mapper/vg_new-lvbackup  5.0G   33M  5.0G   1% /backup
    /dev/mapper/vg_root-lvvar    5.0G  1.2G  3.9G  23% /var
    /dev/mapper/vg_new-lvnew      80G   47G   34G  58% /neworiental
    /dev/mapper/vg_root-lvtmp    5.0G   80M  5.0G   2% /tmp
    tmpfs                        3.2G     0  3.2G   0% /run/user/0

把剩下的20G再加上

[root@XXGL-T-TJSYZ-REDIS-03 ~]# lvextend -L +20G /dev/vg_new/lvnew
      Size of logical volume vg_new/lvnew changed from 79.50 GiB (20352 extents) to 99.50 GiB (25472 extents).
      Logical volume vg_new/lvnew successfully resized.
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# 
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# xfs_growfs /dev/vg_new/lvnew
    meta-data=/dev/mapper/vg_new-lvnew isize=512    agcount=16, agsize=1310720 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0 spinodes=0
    data     =                       bsize=4096   blocks=20840448, 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 20840448 to 26083328
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# 
    [root@XXGL-T-TJSYZ-REDIS-03 ~]# df -lh
    Filesystem                   Size  Used Avail Use% Mounted on
    devtmpfs                      16G     0   16G   0% /dev
    tmpfs                         16G  202M   16G   2% /dev/shm
    tmpfs                         16G  1.6G   15G  10% /run
    tmpfs                         16G     0   16G   0% /sys/fs/cgroup
    /dev/mapper/vg_root-lvall     31G   22G  9.5G  70% /
    /dev/mapper/vg_root-lvusr     10G  7.1G  3.0G  71% /usr
    /dev/sda1                    497M  219M  279M  44% /boot
    /dev/mapper/vg_new-lvbackup  5.0G   33M  5.0G   1% /backup
    /dev/mapper/vg_root-lvvar    5.0G  1.2G  3.9G  23% /var
    /dev/mapper/vg_new-lvnew     100G   47G   54G  47% /neworiental
    /dev/mapper/vg_root-lvtmp    5.0G   80M  5.0G   2% /tmp
    tmpfs                        3.2G     0  3.2G   0% /run/user/0
    [root@XXGL-T-TJSYZ-REDIS-03 ~]#

OK，完成扩容，已经是100G了。

简单的总结一下步骤：

fdisk -l //查看磁盘列表
    
    fdisk /dev/sdb //进入磁盘
    ...
    ...
    ...
    
    partprobe //刷新
    
    pvcreate  /dev/sdb4 //创建PV：pvcreate 分区名
    
    vgextend vg0 /dev/sdb4 // 扩容vg：vgextend vg名 分区名
    
    lvextend -L +50G /dev/vg0/lv_root //扩展lv lvextend -L +size{
        单位} lv具体路径
    
    resize2fs /dev/vg0/lv_root //刷新文件系统，ext4类型用resize2fs，xfs类型用xfs_growfs

### 创建LV ###

如果要创建新的LV，前两步和扩容是一样的：都是创建分区、创建PV，所以从第三步讲：

3、根据PV创建VG

4、根据VG创建LV

5、挂载到目录

6、开机自动挂载

注意，以下操作是在另一台机器上进行的，PV还是/dev/sdb2，并不是之前使用过的。

创建新的VG：vgcreate VG名称 PV路径

[root@XXGL-T-TJSYZ-REDIS-01 ~]# vgcreate vg_rmq /dev/sdb2 
      Volume group "vg_rmq" successfully created
    [root@XXGL-T-TJSYZ-REDIS-01 ~]# vgdisplay
      --- Volume group ---
      VG Name               vg_root
      System ID             
      Format                lvm2
      Metadata Areas        2
      Metadata Sequence No  9
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                5
      Open LV               5
      Max PV                0
      Cur PV                2
      Act PV                2
      VG Size               <55.00 GiB
      PE Size               4.00 MiB
      Total PE              14079
      Alloc PE / Size       14055 / 54.90 GiB
      Free  PE / Size       24 / 96.00 MiB
      VG UUID               OGWFcu-Tl5c-mMUM-mGvr-zfre-krJb-O354MX
       
      --- Volume group ---
      VG Name               vg_rmq
      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               <40.00 GiB
      PE Size               4.00 MiB
      Total PE              10239
      Alloc PE / Size       0 / 0   
      Free  PE / Size       10239 / <40.00 GiB
      VG UUID               arB9H1-eHeS-3inJ-Ukle-hyQ2-p4Oe-6z41Wj
       
      --- Volume group ---
      VG Name               vg_new
      System ID             
      Format                lvm2
      Metadata Areas        3
      Metadata Sequence No  12
      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               <64.50 GiB
      PE Size               4.00 MiB
      Total PE              16511
      Alloc PE / Size       16487 / 64.40 GiB
      Free  PE / Size       24 / 96.00 MiB
      VG UUID               UOiRzY-x5yr-4ZCn-JtWw-hNIg-SgSc-etx1kO
       
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

可以看到新的VG：vg\_rmq已创建成功

接下来创建LV，创建LV之前，需要先确认VG所剩余的容量，因为VG真正的剩余容量是不足40G的，可以直接使用：lvcreate -L 39G -n LV名称 VG名称创建，即容量比40G少一点，也可先查看VG剩余的容量，再精确创建，使用命令：vgs -o +vg\_free\_count,vg\_extent\_count查看所有VG的容量剩余情况。

[root@XXGL-T-TJSYZ-REDIS-01 ~]# vgs -o +vg_free_count,vg_extent_count
      VG      #PV #LV #SN Attr   VSize   VFree   Free  #Ext 
      vg_new    3   2   0 wz--n- <64.50g  96.00m    24 16511
      vg_rmq    1   0   0 wz--n- <40.00g <40.00g 10239 10239
      vg_root   2   5   0 wz--n- <55.00g  96.00m    24 14079
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

可以看到还剩10239，为什么是这么些呢？具体需要看一下PE、LE相关知识，这里不做介绍，接下来使用命令精确创建：lvcreate -l大小 -n LV名称 VG名称（注意：小写的“l”别忘了）

[root@XXGL-T-TJSYZ-REDIS-01 ~]# lvcreate -l10239 -n lv_rmq_01 vg_rmq
      Logical volume "lv_rmq_01" created.
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

可以看到，LV：lv\_rmq\_01创建成功，接下来需要创建LV对应的文件系统：mkfs.xfs LV路径，LV的路径可以通过命令lvdisplay查看：

[root@XXGL-T-TJSYZ-REDIS-01 /]# lvdisplay
    	...
      ...
      ...
      --- Logical volume ---
      LV Path                /dev/vg_rmq/lv_rmq_01
      LV Name                lvnew
      VG Name                vg_new
      LV UUID                0M2v3T-LHZs-8lkR-ocbC-v0bs-eRz2-BjRsf2
      LV Write Access        read/write
      LV Creation host, time localhost.localdomain, 2017-06-15 10:23:32 +0800
      LV Status              available
      # open                 1
      LV Size                99.40 GiB
      Current LE             25447
      Segments               5
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     256
      Block device           253:5
    	...
    	...
    	...
    [root@XXGL-T-TJSYZ-REDIS-01 /]#

创建文件系统（Filesystem）  
mkfs.xfs lv路径（ LV Path）

[root@XXGL-T-TJSYZ-REDIS-01 ~]# mkfs.xfs /dev/vg_rmq/lv_rmq_01
    meta-data=/dev/vg_rmq/lv_rmq_01  isize=512    agcount=4, agsize=2621184 blks
             =                       sectsz=512   attr=2, projid32bit=1
             =                       crc=1        finobt=0, sparse=0
    data     =                       bsize=4096   blocks=10484736, imaxpct=25
             =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
    log      =internal log           bsize=4096   blocks=5119, version=2
             =                       sectsz=512   sunit=0 blks, lazy-count=1
    realtime =none                   extsz=4096   blocks=0, rtextents=0
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

挂载文件系统到新的文件目录：mount LV路径 文件夹路径

[root@XXGL-T-TJSYZ-REDIS-01 ~]# mkdir /zhurunhua
    [root@XXGL-T-TJSYZ-REDIS-01 ~]# mount /dev/vg_rmq/lv_rmq_01 /zhurunhua
    [root@XXGL-T-TJSYZ-REDIS-01 ~]#

检查：

[root@XXGL-T-TJSYZ-REDIS-01 /]# df -lh
    Filesystem                      Size  Used Avail Use% Mounted on
    devtmpfs                        16G     0   16G   0% /dev
    tmpfs                           16G  113M   16G   1% /dev/shm
    tmpfs                           16G  1.6G   15G  10% /run
    tmpfs                           16G     0   16G   0% /sys/fs/cgroup
    /dev/mapper/vg_root-lvall       31G   13G   19G  39% /
    /dev/mapper/vg_root-lvusr       10G  6.8G  3.3G  68% /usr
    /dev/mapper/vg_root-lvtmp       5.0G   43M  5.0G   1% /tmp
    /dev/mapper/vg_root-lvvar       5.0G  2.2G  2.9G  43% /var
    /dev/mapper/vg_rmq-lv_rmq_01    100G   52G   49G  52% /zhurunhua
    [root@XXGL-T-TJSYZ-REDIS-01 /]#

开机自动挂载

修改/etc/fstab文件，添加以下信息

/dev/mapper/vg_rmq-lv_rmq_01 /zhurunhua xfs defaults 1 1
    
    第1列是设备名或者卷标（可通过df -lh查看：Filesystem列对应的信息）
    第2列是挂载点（也就是挂载目录）
    第3列是所要挂载设备的文件系统或者文件系统类型
    第4列是挂载选项，通常使用defaults就可以
    第5列设置是否使用dump备份，置0为不备份，置1，2为备份，但2的备份重要性比1小
    第6列设置是否开机的时候使用fsck检验所挂载的磁盘，置0为不检验，置1，2为检验，但置2盘比置1的盘晚检验。

后记：由于是第一次操作，也遇到一些问题，比如刚开始是想扩容的，但是操作成了创建，然后把新创建的LV挂到了文件目录上，导致一进去目录是空的，给我吓的，后来查了一下，把目录挂载到之前的文件系统就行了，然后又把新创建的LV、VG删掉，删LV的时候需要先从文件目录上卸载，卸载之前要把所有使用该目录的进程干掉，删完新创建的VG之后，又把PV重新扩展到需要扩容的VG中，才重新回到扩容的正轨，总之，纸上得来终觉浅，觉知此事要躬行，实践是检验真理的唯一标准，学习到很多，收获很多，路漫漫其修远兮，吾将上下而求索。

The End.

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