LVM 的基本概念

物理卷 Physical volume (PV)

可以在上面建立卷组的媒介，可以是硬盘分区，也可以是硬盘本身或者回环文件（loopback file）。物理卷包括一个特殊的 header，其余部分被切割为一块块物理区域（physical extents）。

卷组 Volume group (VG)

将一组物理卷收集为一个管理单元。

逻辑卷 Logical volume (LV)

虚拟分区，由物理区域（physical extents）组成。

物理区域 Physical extent (PE)

硬盘可供指派给逻辑卷的最小单位（通常为 4MB）。

磁盘操作相关命令

df -h（查看挂载点）

Filesystem                         Size  Used Avail Use% Mounted on
udev                               1.9G     0  1.9G   0% /dev
tmpfs                              395M  1.9M  393M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv   19G   15G  2.7G  85% /
tmpfs                              2.0G     0  2.0G   0% /dev/shm
tmpfs                              5.0M     0  5.0M   0% /run/lock
tmpfs                              2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/vda2                          976M  214M  695M  24% /boot
/dev/vda1                          511M  6.1M  505M   2% /boot/efi

vgdisplay（显示当前的 volume group）

--- 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               <18.50 GiB
  PE Size               4.00 MiB
  Total PE              4735
  Alloc PE / Size       4735 / <18.50 GiB
  Free  PE / Size       0 / 0
  VG UUID               85kJd0-aNqp-xkoX-HoGI-21DD-l2yL-Gn0Vzs

备注： 注意 VG SIZE，这里应该是你当前的可用空间大小，待扩容完毕，这里显示的应该是最终的大小

pvdisplay （显示当前的 physical volume）

--- Physical volume ---
  PV Name               /dev/vda3
  VG Name               ubuntu-vg
  PV Size               <18.50 GiB / not usable 2.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              4735
  Free PE               0
  Allocated PE          4735
  PV UUID               VJipfU-IpDx-HOqN-ljM4-KXjJ-V7cP-yuwuzf

开始 LVM 扩容

查看 fdisk

fdisk -l

Disk /dev/vda: 20 GiB, 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
Disklabel type: gpt
Disk identifier: 9D1CE45C-69DE-4DCB-9CB0-A2E3C23B3813

Device       Start      End  Sectors  Size Type
/dev/vda1     2048  1050623  1048576  512M EFI System
/dev/vda2  1050624  3147775  2097152    1G Linux filesystem
/dev/vda3  3147776 41940991 38793216 18.5G Linux filesystem


Disk /dev/vdb: 40 GiB, 42949672960 bytes, 83886080 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
Disklabel type: dos
Disk identifier: 0xdab9b80a

Device     Boot Start      End  Sectors Size Id Type
/dev/vdb1        2048 83886079 83884032  40G 83 Linux


Disk /dev/mapper/ubuntu--vg-ubuntu--lv: 18.5 GiB, 19860029440 bytes, 38789120 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

查看所有连接到电脑上的储存设备

fdisk -l |grep '/dev'

2块磁盘效果图（新增磁盘，尚未挂载）

Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
/dev/vda1     2048  1050623  1048576  512M EFI System
/dev/vda2  1050624  3147775  2097152    1G Linux filesystem
/dev/vda3  3147776 41940991 38793216 18.5G Linux filesystem
Disk /dev/vdb: 40 GiB, 42949672960 bytes, 83886080 sectors
Disk /dev/mapper/ubuntu--vg-ubuntu--lv: 18.5 GiB, 19860029440 bytes, 38789120 sectors

创建vdb分区

fdisk /dev/vdb

# 按如下操作
Welcome to fdisk (util-linux 2.31.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

The old ext4 signature will be removed by a write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xdab9b80a.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-83886079, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-83886079, default 83886079):

Created a new partition 1 of type 'Linux' and of size 40 GiB.

Command (m for help): w
The partition table has been altered.
Syncing disks.

格式化磁盘

mkfs -t ext4 /dev/vdb1

# 输出如下：
mke2fs 1.44.1 (24-Mar-2018)
Creating filesystem with 10485504 4k blocks and 2621440 inodes
Filesystem UUID: 368ba4ee-2a69-4d8d-80a3-bc61c82b7fd2
Superblock backups stored on blocks:
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
	4096000, 7962624

Allocating group tables: done
Writing inode tables: done
Creating journal (65536 blocks): done
Writing superblocks and filesystem accounting information: done

创建 PV

pvcreate /dev/vdb1

查看卷组

pvscan

# 输出如下：
PV /dev/vda3   VG ubuntu-vg       lvm2 [<18.50 GiB / 0    free]
  PV /dev/vdb1                      lvm2 [<40.00 GiB]
  Total: 2 [<58.50 GiB] / in use: 1 [<18.50 GiB] / in no VG: 1 [<40.00 GiB]

扩容 VG

vgdisplay

# 输出如下：
--- 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               <18.50 GiB
  PE Size               4.00 MiB
  Total PE              4735
  Alloc PE / Size       4735 / <18.50 GiB
  Free  PE / Size       0 / 0
  VG UUID               85kJd0-aNqp-xkoX-HoGI-21DD-l2yL-Gn0Vzs

vgextend ubuntu-vg /dev/vdb1

# 输出如下：
Volume group "ubuntu-vg" successfully extended

vgdisplay

--- Volume group ---
  VG Name               ubuntu-vg
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  3
  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               58.49 GiB
  PE Size               4.00 MiB
  Total PE              14974
  Alloc PE / Size       4735 / <18.50 GiB
  # 此处即为可以扩容的大小
  Free  PE / Size       10239 / <40.00 GiB
  VG UUID               85kJd0-aNqp-xkoX-HoGI-21DD-l2yL-Gn0Vzs

lvdisplay

--- Logical volume ---
  # 扩容路径
  LV Path                /dev/ubuntu-vg/ubuntu-lv
  LV Name                ubuntu-lv
  VG Name                ubuntu-vg
  LV UUID                DYHQsn-UfPl-OOtz-O1aI-9PzP-gGb6-L2XVXz
  LV Write Access        read/write
  LV Creation host, time ubuntu-server, 2020-09-09 23:39:29 +0800
  LV Status              available
  # open                 1
  LV Size                <18.50 GiB
  Current LE             4735
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

扩容 LV

# 增加指定大小
lvextend -L +30G /dev/ubuntu-vg/ubuntu-lv
# 按百分比扩容
lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv

# 输出如下：
Size of logical volume ubuntu-vg/ubuntu-lv changed from <18.50 GiB (4735 extents) to 58.49 GiB (14974 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.

刷新分区

resize2fs /dev/ubuntu-vg/ubuntu-lv

df -h 
# 成功扩容：
Filesystem                         Size  Used Avail Use% Mounted on
udev                               1.9G     0  1.9G   0% /dev
tmpfs                              395M  1.9M  393M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv   58G   15G   41G  27% /
tmpfs                              2.0G     0  2.0G   0% /dev/shm
tmpfs                              5.0M     0  5.0M   0% /run/lock
tmpfs                              2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/vda2                          976M  214M  695M  24% /boot
/dev/vda1                          511M  6.1M  505M   2% /boot/efi