解决ubuntu--vg-ubuntu--lv磁盘空间不足

安装 Ubuntu Server 的时候 磁盘分区 选择了 LVM，所以系统根目录默认占用磁盘大小只有 4G，在安装软件时发现磁盘空间 4G 已经无法满足，所以需要利用 LVM 对磁盘进行扩容

• 使用 Docker 拉取 MySQL 镜像时发现磁盘空间不够：no space left on device

  root@ubuntu:~# docker pull mysql:5.7.29
  5.7.29: Pulling from library/mysql
  68ced04f60ab: Pull complete 
  f9748e016a5c: Pull complete 
  da54b038fed1: Pull complete 
  6895ec5eb2c0: Pull complete 
  111ba0647b87: Pull complete 
  c1dce60f2f1a: Pull complete 
  702ec598d0af: Pull complete 
  63cca87a5d4d: Pull complete 
  ec05b7b1c5c7: Extracting [==================================================>]  112.2MB/112.2MB
  834b1d9f49b0: Download complete 
  8ded6a30c87c: Download complete 
  failed to register layer: Error processing tar file(exit status 1): write /usr/sbin/mysqld: no space left on device

• 查看文件系统磁盘空间的使用情况

  root@ubuntu:~# df -h
  Filesystem                         Size  Used Avail Use% Mounted on
  udev                               451M     0  451M   0% /dev
  tmpfs                               97M  1.3M   96M   2% /run
  /dev/mapper/ubuntu--vg-ubuntu--lv  3.9G  3.4G  287M  93% /
  tmpfs                              482M     0  482M   0% /dev/shm
  tmpfs                              5.0M     0  5.0M   0% /run/lock
  tmpfs                              482M     0  482M   0% /sys/fs/cgroup
  /dev/loop0                          92M   92M     0 100% /snap/core/8689
  /dev/loop1                          90M   90M     0 100% /snap/core/8268
  /dev/sda2                          976M   77M  832M   9% /boot
  tmpfs                               97M     0   97M   0% /run/user/0

  可以发现 /dev/mapper/ubuntu--vg-ubuntu--lv 虚拟机根目录空间只有 3.9G，使用了 93%，不足以再安装 MySQL

• 查看 LVM 卷组的信息

  root@ubuntu:~# vgdisplay
    --- Volume group ---
    VG Name               ubuntu-vg
    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               <19.00 GiB
    PE Size               4.00 MiB
    Total PE              4863
    Alloc PE / Size       1024 / 4.00 GiB
    Free  PE / Size       3839 / <15.00 GiB
    VG UUID               hZPoxm-kSBU-fmKs-2yXD-hHoe-3T7e-PCIFSe

  Free PE / Size 3839 / <15.00 GiB，这是还可以扩充的大小

• 使用命令进行磁盘扩容

  lvextend -L 10G /dev/mapper/ubuntu--vg-ubuntu--lv      //增大或减小至19G
  lvextend -L +10G /dev/mapper/ubuntu--vg-ubuntu--lv     //增加10G
  lvreduce -L -10G /dev/mapper/ubuntu--vg-ubuntu--lv     //减小10G
  lvresize -l  +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv   //按百分比扩容
  
  resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv            //执行调整

• 具体操作如下

  // 按百分比进行磁盘扩容
  root@ubuntu:~# lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv
    Size of logical volume ubuntu-vg/ubuntu-lv changed from 4.00 GiB (1024 extents) to <19.00 GiB (4863 extents).
    Logical volume ubuntu-vg/ubuntu-lv successfully resized.
  
  // 刷新分区
  root@ubuntu:~# resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv 
  resize2fs 1.44.1 (24-Mar-2018)
  Filesystem at /dev/mapper/ubuntu--vg-ubuntu--lv is mounted on /; on-line resizing required
  old_desc_blocks = 3, new_desc_blocks = 3
  The filesystem on /dev/mapper/ubuntu--vg-ubuntu--lv is now 4979712 (4k) blocks long.
  
  // 查看文件系统磁盘空间的使用情况（发现此时已经扩容到19G）
  root@ubuntu:~# df -h
  Filesystem                         Size  Used Avail Use% Mounted on
  udev                               451M     0  451M   0% /dev
  tmpfs                               97M  1.3M   96M   2% /run
  /dev/mapper/ubuntu--vg-ubuntu--lv   19G  3.9G   14G  22% /
  tmpfs                              482M     0  482M   0% /dev/shm
  tmpfs                              5.0M     0  5.0M   0% /run/lock
  tmpfs                              482M     0  482M   0% /sys/fs/cgroup
  /dev/loop0                          92M   92M     0 100% /snap/core/8689
  /dev/loop1                          90M   90M     0 100% /snap/core/8268
  /dev/sda2                          976M   77M  832M   9% /boot
  tmpfs                               97M     0   97M   0% /run/user/0
  
  // 再次查看LVM卷组的信息（可扩容的空间已经成为0）
  root@ubuntu:~# vgdisplay
    --- Volume group ---
    VG Name               ubuntu-vg
    System ID
    Format                lvm2
    Metadata Areas        1
    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                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               hZPoxm-kSBU-fmKs-2yXD-hHoe-3T7e-PCIFSe