虚拟机LVM卷扩展实际操作

一、LVM

LVM是逻辑盘卷管理（Logical Volume Manager）的简称，它是Linux环境下对磁盘分区进行管理的一种机制，LVM是建立在硬盘和分区之上的一个逻辑层，来提高磁盘分区管理的灵活性。LVM是在磁盘分区和文件系统之间添加的一个逻辑层，来为文件系统屏蔽下层磁盘分区布局，提供一个抽象的盘卷，在盘卷上建立文件系统。物理卷（physical volume）物理卷就是指硬盘分区或从逻辑上与磁盘分区具有同样功能的设备（如RAID），是LVM的基本存储逻辑块，但和基本的物理存储介质（如分区、磁盘等）比较，却包含有与LVM相关的管理参数。
结构：在整个LVM结构当中以此分为：“物理卷、物理卷分区、卷组、逻辑卷”，下面我详细解释一下这四种结构：

物理卷：Physical Volume，简称PV，一个物理卷只不过是一个有LVM管理数据添加在里面的物理存储介质。要使用LVM系统，首先对要用于LVM的磁盘进行初始化，初始化的目的就是将磁盘或分区标识为LVM 的物理卷。使用pvcreate 命令可以将一个磁盘标记为 LVM 物理卷。
物理分区：Physical Extents，简称PE，LVM将每个物理卷分别叫做物理分区的可寻址存储单元，存储单元的大小通常为几MB。磁盘的开头部分为LVM元数据，之后从索引为零开始，每个物理分区的索引依次递增一，按顺序进行分配。
卷组：Volume Group，简称VG，物理卷可以组织为卷组。卷组可以由一个或多个物理卷组成，同时系统中可以有多个卷组。创建了卷组之后，该卷组（而不是磁盘）便是表示数据存储的实体。因此，尽管以前是将磁盘从一个系统移动到另一个系统，使用了 LVM 之后，会将卷组从一个系统移动到另一个系统。出于这种原因，通常在一个系统上创建多个卷组会比较方便。
逻辑分区：Logical Extents，简称LE，逻辑卷的基本分配单元称为逻辑分区。逻辑分区映射到物理分区，因此，如果物理分区的尺寸小为4MB，那么逻辑分区的尺寸也将为4MB。逻辑卷的大小取决于所分配的逻辑分区数量。

二、实际操作

场景：扩展虚拟机已有磁盘空间。

[root@localhost ~]# cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)

1.vmware为虚拟机增加存储空间

扩展前

[root@localhost ~]# df -hT
Filesystem              Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos-root xfs        47G  2.0G   45G   5% /
devtmpfs                devtmpfs  903M     0  903M   0% /dev
tmpfs                   tmpfs     915M     0  915M   0% /dev/shm
tmpfs                   tmpfs     915M  9.4M  906M   2% /run
tmpfs                   tmpfs     915M     0  915M   0% /sys/fs/cgroup
/dev/sda1               xfs      1014M  146M  869M  15% /boot
tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
[root@localhost ~]# fdisk -l

Disk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 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
Disk label type: dos
Disk identifier: 0x000ad192

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200   104857599    51379200   8e  Linux LVM

Disk /dev/mapper/centos-root: 50.5 GB, 50457477120 bytes, 98549760 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


Disk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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

• 扩展操作

关闭虚拟机-设置-硬盘(SCSI)-扩展即可！

扩展后（增加10G）
注意：fdisk -l 执行结果，空间增加约10G，但此时df -hT看不出变化。

[root@localhost ~]# df -hT
Filesystem              Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos-root xfs        47G  2.1G   45G   5% /
devtmpfs                devtmpfs  903M     0  903M   0% /dev
tmpfs                   tmpfs     915M     0  915M   0% /dev/shm
tmpfs                   tmpfs     915M  9.3M  906M   2% /run
tmpfs                   tmpfs     915M     0  915M   0% /sys/fs/cgroup
/dev/sda1               xfs      1014M  146M  869M  15% /boot
tmpfs                   tmpfs     183M     0  183M   0% /run/user/0
[root@localhost ~]# fdisk -l

Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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
Disk label type: dos
Disk identifier: 0x000ad192

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200   104857599    51379200   8e  Linux LVM

Disk /dev/mapper/centos-root: 50.5 GB, 50457477120 bytes, 98549760 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


Disk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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

2.创建分区

说明：
m-帮助
n-新建分区
t-修改分区类型（与原先保持一致，都是8e，代表Linux LVM）
w-保存
q-退出

[root@localhost ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   g   create a new empty GPT partition table
   G   create an IRIX (SGI) partition table
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): p

Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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
Disk label type: dos
Disk identifier: 0x000ad192

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200   104857599    51379200   8e  Linux LVM

Command (m for help): n
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p):
Using default response p
Partition number (3,4, default 3):
First sector (104857600-125829119, default 104857600):
Using default value 104857600
Last sector, +sectors or +size{K,M,G} (104857600-125829119, default 125829119):
Using default value 125829119
Partition 3 of type Linux and of size 10 GiB is set

Command (m for help): p

Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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
Disk label type: dos
Disk identifier: 0x000ad192

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200   104857599    51379200   8e  Linux LVM
/dev/sda3       104857600   125829119    10485760   83  Linux

Command (m for help): t
Partition number (1-3, default 3): 3
Hex code (type L to list all codes): L

 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris
 1  FAT12           27  Hidden NTFS Win 82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      39  Plan 9          83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       3c  PartitionMagic  84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      40  Venix 80286     85  Linux extended  c7  Syrinx
 5  Extended        41  PPC PReP Boot   86  NTFS volume set da  Non-FS data
 6  FAT16           42  SFS             87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS/exFAT 4d  QNX4.x          88  Linux plaintext de  Dell Utility
 8  AIX             4e  QNX4.x 2nd part 8e  Linux LVM       df  BootIt
 9  AIX bootable    4f  QNX4.x 3rd part 93  Amoeba          e1  DOS access
 a  OS/2 Boot Manag 50  OnTrack DM      94  Amoeba BBT      e3  DOS R/O
 b  W95 FAT32       51  OnTrack DM6 Aux 9f  BSD/OS          e4  SpeedStor
 c  W95 FAT32 (LBA) 52  CP/M            a0  IBM Thinkpad hi eb  BeOS fs
 e  W95 FAT16 (LBA) 53  OnTrack DM6 Aux a5  FreeBSD         ee  GPT
 f  W95 Ext'd (LBA) 54  OnTrackDM6      a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            55  EZ-Drive        a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    56  Golden Bow      a8  Darwin UFS      f1  SpeedStor
12  Compaq diagnost 5c  Priam Edisk     a9  NetBSD          f4  SpeedStor
14  Hidden FAT16 <3 61  SpeedStor       ab  Darwin boot     f2  DOS secondary
16  Hidden FAT16    63  GNU HURD or Sys af  HFS / HFS+      fb  VMware VMFS
17  Hidden HPFS/NTF 64  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE
18  AST SmartSleep  65  Novell Netware  b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 70  DiskSecure Mult bb  Boot Wizard hid fe  LANstep
1c  Hidden W95 FAT3 75  PC/IX           be  Solaris boot    ff  BBT
1e  Hidden W95 FAT1 80  Old Minix
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p

Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 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
Disk label type: dos
Disk identifier: 0x000ad192

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200   104857599    51379200   8e  Linux LVM
/dev/sda3       104857600   125829119    10485760   8e  Linux LVM

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[root@localhost ~]# partprobe
Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only.
[root@localhost ~]# reboot

3.创建物理卷

注意：
/dev/sda3 的Allocatable为NO，PE Size为0

[root@localhost ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               <49.00 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              12543
  Free PE               1
  Allocated PE          12542
  PV UUID               9X3qlf-viCH-Cymx-D1eI-vKdd-Ua14-F4bweF

[root@localhost ~]# pvcreate /dev/sda3
  Physical volume "/dev/sda3" successfully created.
[root@localhost ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               <49.00 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              12543
  Free PE               1
  Allocated PE          12542
  PV UUID               9X3qlf-viCH-Cymx-D1eI-vKdd-Ua14-F4bweF

  "/dev/sda3" is a new physical volume of "10.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sda3
  VG Name
  PV Size               10.00 GiB
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               dR5sDM-j21d-xGiB-32WH-xhe4-Sa96-t03jtb

4.扩展卷组

[root@localhost ~]# vgdisplay
  --- Volume group ---
  VG Name               centos
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               <49.00 GiB
  PE Size               4.00 MiB
  Total PE              12543
  Alloc PE / Size       12542 / 48.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               682d9M-yRsn-60BJ-cY7f-nAVI-WA24-KmnhD1

[root@localhost ~]# vgextend centos /dev/sda3
  Volume group "centos" successfully extended
[root@localhost ~]# vgdisplay
  --- Volume group ---
  VG Name               centos
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               58.99 GiB
  PE Size               4.00 MiB
  Total PE              15102
  Alloc PE / Size       12542 / 48.99 GiB
  Free  PE / Size       2560 / 10.00 GiB
  VG UUID               682d9M-yRsn-60BJ-cY7f-nAVI-WA24-KmnhD1

5.逻辑卷扩展

[root@localhost ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                DmOkUA-Fq7K-eTwy-I338-jwiv-Qt7g-s9kdFW
  LV Write Access        read/write
  LV Creation host, time localhost, 2020-01-08 11:35:41 -0500
  LV Status              available
  # open                 2
  LV Size                2.00 GiB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1

  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                KZEsXa-9uNA-Nei7-gnu3-1tmU-BDwq-LSFo7Q
  LV Write Access        read/write
  LV Creation host, time localhost, 2020-01-08 11:35:42 -0500
  LV Status              available
  # open                 1
  LV Size                46.99 GiB
  Current LE             12030
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

[root@localhost ~]# lvextend -l +100%free /dev/mapper/centos-root
  Size of logical volume centos/root changed from 46.99 GiB (12030 extents) to 56.99 GiB (14590 extents).
  Logical volume centos/root successfully resized.

6.动态格式化扩容磁盘

[root@localhost ~]# lvextend -l +100%free /dev/mapper/centos-root
  Size of logical volume centos/root changed from 46.99 GiB (12030 extents) to 56.99 GiB (14590 extents).
  Logical volume centos/root successfully resized.
[root@localhost ~]# man lvextend
[root@localhost ~]# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=3079680 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=12318720, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=6015, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 12318720 to 14940160

7.验证(成功)

[root@localhost ~]# df -hT
Filesystem              Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos-root xfs        57G  2.1G   55G   4% /
devtmpfs                devtmpfs  903M     0  903M   0% /dev
tmpfs                   tmpfs     915M     0  915M   0% /dev/shm
tmpfs                   tmpfs     915M  9.3M  906M   2% /run
tmpfs                   tmpfs     915M     0  915M   0% /sys/fs/cgroup
/dev/sda1               xfs      1014M  146M  869M  15% /boot
tmpfs                   tmpfs     183M     0  183M   0% /run/user/0

三、汇总

调整磁盘大小前强烈建议对重要数据进行备份，特别是数据库数据。

df -hT
# 列出磁盘
fdisk -l
# 操作磁盘/dev/sda
fdisk /dev/sda

Command (m for help): p
Command (m for help): n
Command (m for help): t
Command (m for help): w

# 同步磁盘状态（若同步失败，重启虚拟机）
partprobe
reboot
# 查看物理卷
pvdisplay
# 创建物理卷
pvcreate /dev/sda3
# 查看卷组（1个或多个）
vgdisplay
# 扩展卷组centos 
vgextend centos /dev/sda3
# 查看lvm卷
lvdisplay
# 扩展lvm卷/dev/mapper/centos-root
lvextend -l +100%free /dev/mapper/centos-root
# 动态扩容
xfs_growfs /dev/mapper/centos-root
# 确认
df -hT

若宿主机新增一块磁盘；第2步（创建分区）改为操作磁盘/dev/sdb即可！

```shell
[root@localhost ~]# fdisk /dev/sdb

转载：
LVM扩展卷