LVM磁盘扩容

一、基本概念熟悉

LVM是 Logical Volume Manager（逻辑卷管理）它是Linux环境下对磁盘分区进行管理的一种机制。
LVM 的核心概念有:

• 物理卷 (PV): 一块物理硬盘, 或者硬盘上的一个分区. 也就是底层的物理存储设备.
• 卷组 (VG): 多个 PV 组成的一个存储池, 相当于一块虚拟大硬盘.
• 逻辑卷 (LV): 从 VG 之中划分, 相当于一个虚拟分区

将 PV 划分为许多小的数据存储块 (PE, 默认 4MB), VG 就是一堆 PE 的集合, 然后把 PE 分配给 LV. 当上层软件 (比如 filesystem 文件系统) 访问 LV 时, LVM 找出要访问的数据对应哪个 PE, 从而访问对应的 PV。

二、LVM扩容

Linux操作系统运行一段时间后，磁盘空间不足，需进行扩容。现将扩容过程进行记录。

1. 记录扩容前磁盘使用情况

查看磁盘分区情况：

[root@PAGL-FXQ-TEST ~]# fdisk -l

Disk /dev/vda: 1099.5 GB, 1099511627776 bytes, 2147483648 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: 0x000a9d54

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     2099199     1048576   83  Linux
/dev/vda2         2099200  2147483647  1072692224   8e  Linux LVM

Disk /dev/mapper/centos-root: 2181.0 GB, 2181029691392 bytes, 4259823616 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: 16.9 GB, 16911433728 bytes, 33030144 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/vdb: 1099.5 GB, 1099511627776 bytes, 2147483648 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: 0x3cfffab4

   Device Boot      Start         End      Blocks   Id  System
/dev/vdb1            2048  2147483647  1073740800   83  Linux

查看pv、vg、lv 情况（清楚pv的剩余情况；vg的名称和剩余情况；lv名称和剩余情况）

[root@PAGL-FXQ-TEST ~]# pvs
  PV         VG     Fmt  Attr PSize     PFree
  /dev/vda2  centos lvm2 a--  <1023.00g    0
  /dev/vdb1  centos lvm2 a--  <1024.00g    0
[root@PAGL-FXQ-TEST ~]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree
  centos   2   2   0 wz--n- <2.00t    0
[root@PAGL-FXQ-TEST ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao----  1.98t
  swap centos -wi-ao---- 15.75g

列出所有块设备的基本信息，包括设备名、大小和挂载点等

[root@PAGL-FXQ-TEST ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0              11:0    1  4.4G  0 rom  /mnt/cdrom
vda             252:0    0    1T  0 disk
├─vda1          252:1    0    1G  0 part /boot
└─vda2          252:2    0 1023G  0 part
  ├─centos-root 253:0    0    2T  0 lvm  /
  └─centos-swap 253:1    0 15.8G  0 lvm  [SWAP]
vdb             252:16   0    1T  0 disk
└─vdb1          252:17   0 1024G  0 part
  └─centos-root 253:0    0    2T  0 lvm  /

查看磁盘空间占用情况（知道根分区空间占93%，空间严重不足）

[root@PAGL-FXQ-TEST ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                  16G     0   16G   0% /dev
tmpfs                     16G  9.3M   16G   1% /dev/shm
tmpfs                     16G  1.5G   15G  10% /run
tmpfs                     16G     0   16G   0% /sys/fs/cgroup
/dev/mapper/centos-root  2.0T  1.9T  148G  93% /
/dev/vda1               1014M  202M  813M  20% /boot
tmpfs                    3.2G   52K  3.2G   1% /run/user/0
/dev/sr0                 4.4G  4.4G     0 100% /mnt/cdrom

2. 虚拟机添加磁盘

3. 添加磁盘后检查

可以看出多了/dev/vdc磁盘，如下：

  [root@PAGL-FXQ-TEST ~]# fdisk -l

Disk /dev/vda: 1099.5 GB, 1099511627776 bytes, 2147483648 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: 0x000a9d54

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     2099199     1048576   83  Linux
/dev/vda2         2099200  2147483647  1072692224   8e  Linux LVM

Disk /dev/mapper/centos-root: 2181.0 GB, 2181029691392 bytes, 4259823616 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: 16.9 GB, 16911433728 bytes, 33030144 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/vdb: 1099.5 GB, 1099511627776 bytes, 2147483648 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: 0x3cfffab4

   Device Boot      Start         End      Blocks   Id  System
/dev/vdb1            2048  2147483647  1073740800   83  Linux

Disk /dev/vdc: 2199.0 GB, 2199023255552 bytes, 4294967296 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

4.将新硬盘分区初始化

  [root@PAGL-FXQ-TEST centos]# pvcreate /dev/vdc
  Physical volume "/dev/vdc" successfully created.
  [root@PAGL-FXQ-TEST centos]# pvs
  PV         VG     Fmt  Attr PSize     PFree
  /dev/vda2  centos lvm2 a--  <1023.00g    0
  /dev/vdb1  centos lvm2 a--  <1024.00g    0
  /dev/vdc          lvm2 ---      2.00t 2.00t

5.将初始化后的分区添加到VG中

[root@PAGL-FXQ-TEST centos]# vgextend centos /dev/vdc
  Volume group "centos" successfully extended
[root@PAGL-FXQ-TEST centos]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree
  centos   3   2   0 wz--n- <4.00t <2.00t

5.将VG分配给lv

lvm的名称为/dev/centos/root

[root@PAGL-FXQ-TEST centos]# lvextend -l +100%FREE /dev/centos/root
  Size of logical volume centos/root changed from 1.98 TiB (519998 extents) to 3.98 TiB (1044285 extents).
  Logical volume centos/root successfully resized.
[root@PAGL-FXQ-TEST centos]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree
  centos   3   2   0 wz--n- <4.00t    0
[root@PAGL-FXQ-TEST centos]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao----  3.98t
  swap centos -wi-ao---- 15.75g

6.扩展文件系统

注意：lvextend扩展后只是扩展了lv的大小，而此时文件系统并未感知到，所有还需要使用xfs_growfs、resize2fs等命令来扩展文件系统，xfs_growf命令是扩展xfs文件系统，resize2fs是扩展ext4文件系统。

[root@PAGL-FXQ-TEST centos]# xfs_growfs  /dev/centos/root
meta-data=/dev/mapper/centos-root isize=512    agcount=9, agsize=66010624 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=532477952, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=128927, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 532477952 to 1069347840
[root@PAGL-FXQ-TEST centos]# df -h
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                  16G     0   16G   0% /dev
tmpfs                     16G  9.3M   16G   1% /dev/shm
tmpfs                     16G  1.5G   15G  10% /run
tmpfs                     16G     0   16G   0% /sys/fs/cgroup
/dev/mapper/centos-root  4.0T  1.9T  2.2T  47% /
/dev/vda1               1014M  202M  813M  20% /boot
tmpfs                    3.2G   52K  3.2G   1% /run/user/0
/dev/sr0                 4.4G  4.4G     0 100% /mnt/cdrom

扩容成功！！

参考
https://blog.csdn.net/MssGuo/article/details/120475752
https://www.bilibili.com/read/cv35761174/
https://blog.csdn.net/ichen820/article/details/138958377