【转载】CentOS7下使用LVM给系统硬盘扩容

原文地址：https://www.cnblogs.com/ding2016/p/9680690.html

简单介绍：

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。通过LVM系统管理员可以轻松管理磁盘分区，如：将若干个磁盘分区连接为一个整块的卷组（volumegroup），形成一个存储池。管理员可以在卷组上随意创建逻辑卷组（logicalvolumes），并进一步在逻辑卷组上创建文件系统。管理员通过LVM可以方便的调整存储卷组的大小，并且可以对磁盘存储按照组的方式进行命名、管理和分配。

扩容方案：

①添加新硬盘，并把新硬盘通过mount挂载到指定挂载点；（比如新建一个/data目录，把新硬盘挂载到/data下提供使用）

②添加新硬盘，通过LVM把新硬盘的空间划给原系统盘，实现动态扩容系统盘；（也可以在虚拟机设置里调大原有磁盘，再扩容）

此处记录一下在centos7下方案②的操作步骤。

测试目标：

把一台CentOS7.4虚拟机原系统磁盘扩容10G。（原系统盘30G，扩容至40G）

操作步骤：

1. 虚拟机编辑设置添加一块新硬盘

2. 查看一下

[root@server-10 ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 990M     0  990M   0% /dev
tmpfs                   1001M     0 1001M   0% /dev/shm
tmpfs                   1001M   57M  944M   6% /run
tmpfs                   1001M     0 1001M   0% /sys/fs/cgroup
/dev/mapper/centos-root   27G  5.8G   22G  22% /　　　　// 扩容后，再来看该项，作对比
/dev/sda1               1014M  154M  861M  16% /boot
tmpfs                    201M     0  201M   0% /run/user/0
[root@server-10 ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   30G  0 disk 
├─sda1            8:1    0    1G  0 part /boot
└─sda2            8:2    0   29G  0 part 
  ├─centos-root 253:0    0   27G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   10G  0 disk 　　　　// 新加的硬盘命名为sdb，已经存在，但是还没分区无法给系统使用
sr0              11:0    1 1024M  0 rom  

3. 给新硬盘创建分区（此处就默认创建一个分区）

[root@server-10 ~]# fdisk /dev/sdb
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): n　　// 添加新分区
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): 　　// 回车，默认p，主分区
Using default response p
Partition number (1-4, default 1): 　　// 回车，默认1
First sector (2048-20971519, default 2048): 　　// 回车，默认起始位置
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): 　　// 回车，默认最后位置
Using default value 20971519
Partition 1 of type Linux and of size 10 GiB is set

Command (m for help): t　　// 更改分区格式
Selected partition 1
Hex code (type L to list all codes): L　　// 查看可选项
 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　　// 更改分区格式为LVM
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p　　// 打印，查看改好的分区（blocks为分区大小 单位为kb）

Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 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: 0xa6e3dd82

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    20971519    10484736   8e  Linux LVM

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

Calling ioctl() to re-read partition table.
Syncing disks.

4. 再次查看分区，只是分区好，没挂载没加入系统根，无法使用

[root@server-10 ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   30G  0 disk 
├─sda1            8:1    0    1G  0 part /boot
└─sda2            8:2    0   29G  0 part 
  ├─centos-root 253:0    0   27G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   10G  0 disk 
└─sdb1            8:17   0   10G  0 part 
sr0              11:0    1 1024M  0 rom  

5. 把新的分区转换为物理卷

[root@server-10 ~]# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created.

6. 查看现有的卷组名，这里为centos

[root@server-10 ~]# vgdisplay 
  --- Volume group ---
  VG Name               centos　　// 这是Centos系统下默认的VG Name,RHEL系统显示为rhel
  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               <29.00 GiB　　//留意该值的变化
  PE Size               4.00 MiB
  Total PE              7423
  Alloc PE / Size       7422 / 28.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               RNpAgN-PLQm-M4vp-E37i-fhhp-mr2z-faLm3A

7. 把转换号的物理卷并到vg（卷组）中

[root@server-10 ~]# vgextend centos /dev/sdb1
  Volume group "centos" successfully extended

[root@server-10 ~]# 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               38.99 GiB　　//对比，变大了约10G
  PE Size               4.00 MiB
  Total PE              9982
  Alloc PE / Size       7422 / 28.99 GiB
  Free  PE / Size       2560 / 10.00 GiB
  VG UUID               RNpAgN-PLQm-M4vp-E37i-fhhp-mr2z-faLm3A

8. 查看逻辑卷，默认系统分了2个，选择对应逻辑卷路径

[root@server-10 ~]# lvdisplay 
  --- Logical volume ---
  LV Path                /dev/centos/swap　　//系统默认分了2G给swap,不用管
  LV Name                swap
  VG Name                centos
  LV UUID                w8yxWk-Qrth-x16P-jVg3-1haX-lZUH-0r1SkV
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2018-03-21 02:10:16 +0800
  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　　// 后面扩展该逻辑卷，记住该路径
  LV Name                root
  VG Name                centos
  LV UUID                ECEWl4-0AEW-W1Tn-acE2-GLpe-NxeD-v16tGb
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2018-03-21 02:10:16 +0800
  LV Status              available
  # open                 1
  LV Size                26.99 GiB
  Current LE             6910
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

9. 给逻辑卷扩展空间

[root@server-10 ~]# lvextend /dev/centos/root /dev/sdb1
  Size of logical volume centos/root changed from 26.99 GiB (6910 extents) to <36.99 GiB (9469 extents).
  Logical volume centos/root successfully resized.

10. 写入文件系统，使扩容生效。

[root@server-10 ~]# xfs_growfs /dev/mapper/centos-root 
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1768960 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=7075840, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=3455, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 7075840 to 9696256

如果是ext系统，可以使用resize2fs命令替换xfs_growfs命令。

11. 检查扩容效果

[root@server-10 ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 990M     0  990M   0% /dev
tmpfs                   1001M     0 1001M   0% /dev/shm
tmpfs                   1001M   57M  944M   6% /run
tmpfs                   1001M     0 1001M   0% /sys/fs/cgroup
/dev/mapper/centos-root   37G  5.8G   32G  16% /
/dev/sda1               1014M  154M  861M  16% /boot
tmpfs                    201M     0  201M   0% /run/user/0

对比最初的显示，扩容成功。

结束.