放弃阿里云的服务器，将wp迁移到家里的工控机之后一直就有个疑问。安装之后的磁盘空间显示的容量只有硬盘大小的一半。导致我一度以为实际磁盘就是100G的。

于是今天搜索了一下才发现是系统磁盘lvm管理导致的问题，默认安装之后只会使用磁盘一般的空间。

What is LVM

LVM stands for Logical Volume Management. It is a system of managing logical volumes, or filesystems, that is much more advanced and flexible than the traditional method of partitioning a disk into one or more segments and formatting that partition with a filesystem.

 

Why use LVM?

For a long time I wondered why anyone would want to use LVM when you can use gparted to resize and move partitions just fine. The answer is that lvm can do these things better, and some nifty new things that you just can’t do otherwise. I will explain several tasks that lvm can do and why it does so better than other tools, then how to do them. First you should understand the basics of lvm.

obaby@h4ck:~$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
tmpfs                              784M  1.6M  783M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv   98G   29G   65G  31% /
tmpfs                              3.9G     0  3.9G   0% /dev/shm
tmpfs                              5.0M  4.0K  5.0M   1% /run/lock
/dev/sda2                          2.0G  268M  1.6G  15% /boot
/dev/sda1                          1.1G  6.1M  1.1G   1% /boot/efi
tmpfs                              784M   76K  784M   1% /run/user/131
tmpfs                              784M   64K  784M   1% /run/user/1000

df命令可以看到挂载硬盘就是98g。

obaby@h4ck:~$ lsblk
NAME                      MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0                       7:0    0  63.4M  1 loop /snap/core20/1950
loop1                       7:1    0  63.3M  1 loop
loop2                       7:2    0  49.8M  1 loop
loop3                       7:3    0  63.4M  1 loop /snap/core20/1974
loop4                       7:4    0 111.9M  1 loop /snap/lxd/24322
loop5                       7:5    0  53.3M  1 loop /snap/snapd/19457
loop7                       7:7    0  53.3M  1 loop /snap/snapd/19361
sda                         8:0    0 238.5G  0 disk
├─sda1                      8:1    0     1G  0 part /boot/efi
├─sda2                      8:2    0     2G  0 part /boot
└─sda3                      8:3    0 235.4G  0 part
  └─ubuntu--vg-ubuntu--lv 253:0    0   100G  0 lvm  /

lsblk可以看到磁盘是挂载在sda3下面。

obaby@h4ck:~$ sudo 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               235.42 GiB
  PE Size               4.00 MiB
  Total PE              60268
  Alloc PE / Size       25600 / 100.00 GiB
  Free  PE / Size       34668 / 135.42 GiB
  VG UUID               xeAkGF-zg8u-iEMN-DNR9-FeTX-hnHi-UVfS6F

vgdisplay可以看到磁盘vg size 为235G。

所以可以扩展系统分区，由于所有的数据目前都在/home目录下，所以也没必要创建新的分区。当然更稳妥的办法是创建一个新分区挂载之后，数据都放到新分区上。

直接扩展系统分区：

obaby@h4ck:~$ sudo lvextend -l +100%FREE  /dev/mapper/ubuntu--vg-ubuntu--lv
  Size of logical volume ubuntu-vg/ubuntu-lv changed from 100.00 GiB (25600 extents) to 235.42 GiB (60268 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.

重新计算大小：

obaby@h4ck:~$ sudo resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/mapper/ubuntu--vg-ubuntu--lv is mounted on /; on-line resizing required
old_desc_blocks = 13, new_desc_blocks = 30
The filesystem on /dev/mapper/ubuntu--vg-ubuntu--lv is now 61714432 (4k) blocks long.

再次查看磁盘空间：

obaby@h4ck:~$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
tmpfs                              784M  1.6M  783M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv  232G   29G  193G  13% /
tmpfs                              3.9G     0  3.9G   0% /dev/shm
tmpfs                              5.0M  4.0K  5.0M   1% /run/lock
/dev/sda2                          2.0G  268M  1.6G  15% /boot
/dev/sda1                          1.1G  6.1M  1.1G   1% /boot/efi
tmpfs                              784M   76K  784M   1% /run/user/131
tmpfs                              784M   64K  784M   1% /run/user/1000

现在系统盘分区大小就对上了。

参考链接：https://www.bilibili.com/read/cv23646901