1、关闭虚拟机，找到需要扩容的硬盘，修改为新的容量80GB，应用保存。

2、打开VM，进入系统，使用lsblk可以看到硬盘容量已经变为80GB，但硬盘根分区还没有扩容，使用df查看根文件系统也没有扩容。

[192.168.2.108] alpha@mascot.x ~ $ lsblk 
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0    7:0    0 111.9M  1 loop /snap/lxd/24322
loop1    7:1    0  53.3M  1 loop /snap/snapd/19457
loop2    7:2    0  63.4M  1 loop /snap/core20/1974
sda      8:0    0    80G  0 disk 
├─sda1   8:1    0     1M  0 part 
└─sda2   8:2    0    25G  0 part /
sr0     11:0    1  1024M  0 rom  
[192.168.2.108] alpha@mascot.x ~ $ df -h
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           392M  1.1M  391M   1% /run
/dev/sda2        25G  7.7G   16G  33% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           392M  4.0K  392M   1% /run/user/1000

3、使用parted命令修改分区大小：

sudo parted /dev/sda

运行parted命令后，输入help查看命令列表。

[192.168.2.108] alpha@mascot.x ~ $ sudo parted /dev/sda
[sudo] password for alpha: 
GNU Parted 3.4
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) help                                                             align-check TYPE N                       check partition N for TYPE(min|opt) alignmenthelp [COMMAND]                           print general help, or help on COMMANDmklabel,mktable LABEL-TYPE               create a new disklabel (partition table)mkpart PART-TYPE [FS-TYPE] START END     make a partitionname NUMBER NAME                         name partition NUMBER as NAMEprint [devices|free|list,all|NUMBER]     display the partition table, available devices, free space, all found partitions, or a particularpartitionquit                                     exit programrescue START END                         rescue a lost partition near START and ENDresizepart NUMBER END                    resize partition NUMBERrm NUMBER                                delete partition NUMBERselect DEVICE                            choose the device to editdisk_set FLAG STATE                      change the FLAG on selected devicedisk_toggle [FLAG]                       toggle the state of FLAG on selected deviceset NUMBER FLAG STATE                    change the FLAG on partition NUMBERtoggle [NUMBER [FLAG]]                   toggle the state of FLAG on partition NUMBERunit UNIT                                set the default unit to UNITversion                                  display the version number and copyright information of GNU Parted
(parted)  

 输入print命令，打印当前分区表，会提示有可用空间，需要修复GPT，输入Fix修复：

(parted) print                                                            
Warning: Not all of the space available to /dev/sda appears to be used, you can fix the GPT to use all of the space (an extra 115343360
blocks) or continue with the current setting? 
Fix/Ignore? Fix
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sda: 85.9GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: Number  Start   End     Size    File system  Name  Flags1      1049kB  2097kB  1049kB                     bios_grub2      2097kB  26.8GB  26.8GB  ext4(parted) 

 修复GPT之后，可以输入print free查看可用的空间：

(parted) print free                                                       
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sda: 85.9GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: Number  Start   End     Size    File system  Name  Flags17.4kB  1049kB  1031kB  Free Space1      1049kB  2097kB  1049kB                     bios_grub2      2097kB  26.8GB  26.8GB  ext426.8GB  85.9GB  59.1GB  Free Space(parted) 

继续 输入resizepart 2 100%命令，将分区2扩容100%可用空间，输入Yes确认操作：

(parted) resizepart 2 100%                                                
Warning: Partition /dev/sda2 is being used. Are you sure you want to continue?
Yes/No? Yes
(parted)  

 输入q退出parted命令，再用lsblk查看，根分区大小已经变成80G，但使用df查看根文件系统，还是25G，没有扩容。

(parted) q                                                                
Information: You may need to update /etc/fstab.[192.168.2.108] alpha@mascot.x ~ $ lsblk                                  
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0    7:0    0  63.4M  1 loop /snap/core20/1974
loop1    7:1    0 111.9M  1 loop /snap/lxd/24322
loop2    7:2    0  53.3M  1 loop /snap/snapd/19457
loop3    7:3    0  38.8M  1 loop /snap/snapd/21759
loop4    7:4    0  63.9M  1 loop /snap/core20/2318
loop5    7:5    0    87M  1 loop /snap/lxd/28373
sda      8:0    0    80G  0 disk 
├─sda1   8:1    0     1M  0 part 
└─sda2   8:2    0    80G  0 part /
sr0     11:0    1  1024M  0 rom  
[192.168.2.108] alpha@mascot.x ~ $ df -h
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           392M  1.1M  391M   1% /run
/dev/sda2        25G  7.9G   16G  35% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           392M  4.0K  392M   1% /run/user/1000

4、使用resize2fs命令更新文件系统大小，再用df查看根文件系统大小已经更新：

sudo resize2fs /dev/sda2

[192.168.2.108] alpha@mascot.x ~ $ sudo resize2fs /dev/sda2 
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/sda2 is mounted on /; on-line resizing required
old_desc_blocks = 4, new_desc_blocks = 10
The filesystem on /dev/sda2 is now 20971003 (4k) blocks long.[192.168.2.108] alpha@mascot.x ~ $ df -h
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           392M  1.1M  391M   1% /run
/dev/sda2        79G  8.1G   68G  11% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           392M  4.0K  392M   1% /run/user/1000

结束。

参考：

ubuntu 扩展分区并将剩余空间添加到现有逻辑卷中_ubuntu扩展分区大小 将一个磁盘加到另一个当中-CSDN博客