LVM逻辑卷操作实录

ゞ浴缸里的玫瑰 2021-12-16 07:39 306阅读 0赞

之前讲了[LVM基础详细说明][LVM]，现在记录下LVM逻辑卷的操作实录。

# 一、准备物理分区（Physical Partions） #

首先，我们需要选择用于 LVM 的物理存储器。这些通常是标准分区，但也可以是已创建的 Linux Software RAID 卷。这里我利用fdisk命令，将sdb、sdc两块磁盘分了两个区sdb1、sdc1， 通过fdisk的t指令指定分区为8e类型(Linux LVM) ，如下：

[root@localhost ~]# fdisk -l
    
    Disk /dev/sda: 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: 0x00099e91
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1   *        2048   104857599    52427776   83  Linux
    
    Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x8c6de33b
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sdb1            2048    41943039    20970496   8e  Linux LVM
    
    Disk /dev/sdc: 32.2 GB, 32212254720 bytes, 62914560 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: 0xe60d5065
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sdc1            2048    62914559    31456256   8e  Linux LVM

# 二、创建物理卷PV（Physical Volumes） #

[root@localhost ~]# pvcreate /dev/sdb1    # 如果没有pvcreate\命令，可以使用yum install -y lvm2进行安装
      Physical volume "/dev/sdb1" successfully created.
    [root@localhost ~]# pvcreate /dev/sdc1    #可以使用pcvreate /dev/{sdb1,sdc1}
      Physical volume "/dev/sdc1" successfully created.

# 三、创建卷组VG（Volume Groups）,命名为vg\_test1 #

[root@localhost ~]# vgcreate vg_test1 /dev/sdb1 
      Volume group "vg_test1" successfully created
    [root@localhost ~]# vgdisplay 
      --- Volume group ---
      VG Name               vg_test1
      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               <20.00 GiB
      PE Size               4.00 MiB
      Total PE              5119
      Alloc PE / Size       0 / 0   
      Free  PE / Size       5119 / <20.00 GiB
      VG UUID               o8efai-0E75-XBW3-Oaxn-pIf3-BiLS-SpAAD3

# 四、创建逻辑卷LV（Logical Volumes） ,命名为lv\_test1 #

创建逻辑卷的命令为lvcreate，-l 参数为定PE数来设定逻辑分区大小，也可以使用-L参数直接指定逻辑分区大小，-n参数指定逻辑分区名称。

[root@localhost ~]# lvcreate -L 10G -n lv_test1 vg_test1
      Logical volume "lv_test1" created.
    [root@localhost ~]# lvdisplay 
      --- Logical volume ---
      LV Path                /dev/vg_test1/lv_test1
      LV Name                lv_test1
      VG Name                vg_test1
      LV UUID                zcIjip-NOAH-zNyI-lPrB-1f44-wHoi-cgtTSz
      LV Write Access        read/write
      LV Creation host, time localhost.localdomain, 2019-07-05 15:22:45 +0800
      LV Status              available
      # open                 0
      LV Size                10.00 GiB
      Current LE             2560
      Segments               1
      Allocation             inherit
      Read ahead sectors     auto
      - currently set to     256
      Block device           253:0

# 五、创建文件系统并挂载 #

在逻辑卷上创建ext4文件系统:

[root@localhost ~]# mkfs -t ext4 /dev/vg_test1/lv_test1    # 可以直接使用mkfs.ext4进行格式化
    [root@localhost ~]# mount /dev/vg_test1/lv_test1 /data/
    [root@localhost ~]# df -h
    Filesystem                     Size  Used Avail Use% Mounted on
    /dev/sda1                       50G  1.5G   49G   3% /
    devtmpfs                       903M     0  903M   0% /dev
    tmpfs                          912M     0  912M   0% /dev/shm
    tmpfs                          912M  8.6M  904M   1% /run
    tmpfs                          912M     0  912M   0% /sys/fs/cgroup
    tmpfs                          183M     0  183M   0% /run/user/0
    /dev/mapper/vg_test1-lv_test1  9.8G   37M  9.2G   1% /data

# 六、动态调整LVM分区大小 #

LVM的最大好处就是可以动态地调整分区大小，而无须重新启动，下面让我们来体验一下吧！  
继续上面的实例，现假设逻辑卷 /dev/vg\_test1/lv\_test1空间不足，需要增加其大小，我们分两种情况讨论：

## 1、当卷组中有剩余的空间 ##

通过vgdisplay命令可以检查当前卷组空间使用情况:

[root@localhost ~]# vgdisplay 
      --- Volume group ---
      VG Name               vg_test1
      System ID             
      Format                lvm2
      Metadata Areas        1
      Metadata Sequence No  2
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                1
      Open LV               1
      Max PV                0
      Cur PV                1
      Act PV                1
      VG Size               <20.00 GiB
      PE Size               4.00 MiB
      Total PE              5119
      Alloc PE / Size       2560 / 10.00 GiB
      Free  PE / Size       2559 / <10.00 GiB
      VG UUID               o8efai-0E75-XBW3-Oaxn-pIf3-BiLS-SpAAD3

确定当前卷组剩余空间10GB，剩余PE数量为2559个。在这里将所有的剩余空间全部增加给逻辑卷 /dev/vg\_test1/lv\_test1

[root@localhost ~]# lvextend -l +2559 /dev/vg_test1/lv_test1 
      Size of logical volume vg_test1/lv_test1 changed from 10.00 GiB (2560 extents) to <20.00 GiB (5119 extents).
      Logical volume vg_test1/lv_test1 successfully resized.

修改逻辑卷大小后，通过resize2fs来修改文件系统的大小：

[root@localhost ~]# resize2fs /dev/vg_test1/lv_test1 
    resize2fs 1.42.9 (28-Dec-2013)
    Filesystem at /dev/vg_test1/lv_test1 is mounted on /data; on-line resizing required
    old_desc_blocks = 2, new_desc_blocks = 3
    The filesystem on /dev/vg_test1/lv_test1 is now 5241856 blocks long.

再次查看文件系统的大小：

[root@localhost ~]# df -h
    Filesystem                     Size  Used Avail Use% Mounted on
    /dev/sda1                       50G  1.5G   49G   3% /
    devtmpfs                       903M     0  903M   0% /dev
    tmpfs                          912M     0  912M   0% /dev/shm
    tmpfs                          912M  8.6M  904M   1% /run
    tmpfs                          912M     0  912M   0% /sys/fs/cgroup
    tmpfs                          183M     0  183M   0% /run/user/0
    /dev/mapper/vg_test1-lv_test1   20G   44M   19G   1% /data

## 2、当卷组中空间不足时 ##

当卷组中没有足够的空间用于扩展逻辑卷的大小时，就需要增加卷组的容量，而增加卷组容量的唯一办法就是向卷组中添加新的物理卷。  
首先需要对新增加的磁盘进行分区、创建物理卷等工作，接下来是利用vgextend命令将新的物理卷加入到卷组中, 这里使用/dev/sdc1。

[root@localhost ~]# vgextend vg_test1 /dev/sdc1 
      Volume group "vg_test1" successfully extended
    [root@localhost ~]# vgdisplay 
      --- Volume group ---
      VG Name               vg_test1
      System ID             
      Format                lvm2
      Metadata Areas        2
      Metadata Sequence No  4
      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               49.99 GiB
      PE Size               4.00 MiB
      Total PE              12798
      Alloc PE / Size       5119 / <20.00 GiB
      Free  PE / Size       7679 / <30.00 GiB
      VG UUID               o8efai-0E75-XBW3-Oaxn-pIf3-BiLS-SpAAD3

对逻辑卷进行扩容

[root@localhost ~]# lvextend -L +20G /dev/vg_test1/lv_test1  
      Size of logical volume vg_test1/lv_test1 changed from <20.00 GiB (5119 extents) to <40.00 GiB (10239 extents).
      Logical volume vg_test1/lv_test1 successfully resized.

修改逻辑卷大小后，通过resize2fs来修改文件系统的大小：

[root@localhost ~]# resize2fs /dev/vg_test1/lv_test1 
    resize2fs 1.42.9 (28-Dec-2013)
    Filesystem at /dev/vg_test1/lv_test1 is mounted on /data; on-line resizing required
    old_desc_blocks = 3, new_desc_blocks = 5
    The filesystem on /dev/vg_test1/lv_test1 is now 10484736 blocks long.

再次查看文件系统的大小：

参考文章：[https://www.cnblogs.com/kevingrace/p/5845634.html][https_www.cnblogs.com_kevingrace_p_5845634.html]

[LVM]: https://blog.csdn.net/wc1695040842/article/details/94716620
[https_www.cnblogs.com_kevingrace_p_5845634.html]: https://www.cnblogs.com/kevingrace/p/5845634.html