Ubuntu 20.04.3 server 服务器版系统，磁盘如何扩容

环境：
Ubuntu 20.04.3-live-server

问题描述：
Ubuntu 20.04.3-live-server 磁盘如何扩容，磁盘空间有50G，新安装的系统默认只分配20G

1.查看磁盘信息

df -h
Filesystem                         Size  Used Avail Use% Mounted on
udev                               3.9G     0  3.9G   0% /dev
tmpfs                              790M  1.2M  789M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv  19G  0.9G  17G   5% /
tmpfs                              3.9G   16K  3.9G   1% /dev/shm
tmpfs                              5.0M     0  5.0M   0% /run/lock
tmpfs                              3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/loop0                          56M   56M     0 100% /snap/core18/2128
/dev/loop2                          71M   71M     0 100% /snap/lxd/21029
/dev/loop1                          33M   33M     0 100% /snap/snapd/12704
/dev/vda2                          976M  108M  801M  12% /boot
/dev/loop3                          44M   44M     0 100% /snap/snapd/14549
/dev/loop4                          56M   56M     0 100% /snap/core18/2284
/dev/loop5                          62M   62M     0 100% /snap/core20/1328
/dev/loop6                          68M   68M     0 100% /snap/lxd/21835
tmpfs                              790M     0  790M   0% /run/user/0

2.显示存在的卷组信息

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               <499.00 GiB
  PE Size               4.00 MiB
  Total PE              127743
  Alloc PE / Size       51200 / 200.00 GiB
  Free  PE / Size       76543 / <29.00 GiB
  VG UUID               kynKuT-rtTy-Sk9v-txe6-0VKJ-JFxK-2soNbx

Free PE/size显示还有29G可以扩容

解决方案：

1.调整方案

1.例如增大至220G
lvextend -L 220G /dev/mapper/ubuntu--vg-ubuntu--lv    

2.例如减小至80G
lvreduce -L 80G /dev/mapper/ubuntu--vg-ubuntu--lv

3.例如增加120G
lvextend -L +120G /dev/mapper/ubuntu--vg-ubuntu--lv    

4.例如减小10G
lvreduce -L -10G /dev/mapper/ubuntu--vg-ubuntu--lv   

5.例如调整为50G    
lvresize -L  50G /dev/mapper/ubuntu--vg-ubuntu--lv 

6.例如扩容利用Free PE/size全部空间
lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv

（以上选择自己需要扩容的命令）

7.最后执行变更
resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv  

2.扩容

1.这选择输入lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv
  
  Size of logical volume ubuntu-vg/ubuntu-lv changed from 20.00 GiB (51200 extents) to <499.00 GiB (127743 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.

2.执行resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv

resize2fs 1.45.5 (07-Jan-2020)
Filesystem at /dev/mapper/ubuntu--vg-ubuntu--lv is mounted on /; on-line resizing required
old_desc_blocks = 25, new_desc_blocks = 63
The filesystem on /dev/mapper/ubuntu--vg-ubuntu--lv is now 130808832 (4k) blocks long.

3.查看磁盘信息

df -h
Filesystem                         Size  Used Avail Use% Mounted on
udev                               3.9G     0  3.9G   0% /dev
tmpfs                              790M  1.2M  789M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv  49G  0.9G  46G   2% /
tmpfs                              3.9G   16K  3.9G   1% /dev/shm
tmpfs                              5.0M     0  5.0M   0% /run/lock
tmpfs                              3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/loop0                          56M   56M     0 100% /snap/core18/2128
/dev/loop2                          71M   71M     0 100% /snap/lxd/21029
/dev/loop1                          33M   33M     0 100% /snap/snapd/12704
/dev/vda2                          976M  108M  801M  12% /boot
/dev/loop3                          44M   44M     0 100% /snap/snapd/14549
/dev/loop4                          56M   56M     0 100% /snap/core18/2284
/dev/loop5                          62M   62M     0 100% /snap/core20/1328
/dev/loop6                          68M   68M     0 100% /snap/lxd/21835
tmpfs                              790M     0  790M   0% /run/user/0

可以看到：

/dev/mapper/ubuntu–vg-ubuntu–lv 49G 0.9G 46G 2% /

扩容完成