Linux Centos虚拟机扩容（/dev/mapper/centos-root）

场景

我们在使用linux虚拟机时会经常出现空间不够用的情况，下面主要分享下如何增加VMWare虚拟机(Linux)的根目录磁盘空间

实践

1、在虚拟机软件上,为对应的虚拟机扩充20G硬盘空间.

2、启用该虚拟机，使用Linux的fdisk分区工具给磁盘分区

[root@Agile936 ~]# 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: 0x000f0195

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    52428799    25164800   8e  Linux LVM

Disk /dev/mapper/centos-root: 23.6 GB, 23613931520 bytes, 46120960 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

[root@Agile936 ~]#

根据提示可以看到此系统的磁盘接口为scsi，对应‘sda’，下面进行分区.

• 输入m查看帮助信息，
• 再输入n(表示增加分区)，
• 回车后输入p(创建主分区)，
• 回车后partition number输入3(因为上面已经有两个分区sda1和sda2)，
• 回车会提示输入分区的start值(通过fdisk -l 可以看出sda2的end值为40960)，我们可以指定start值为40961，end值为默认即可(即当前最大值)，
• 回车后输入W进行保存，分区划分完毕。

[root@Agile936 ~]# 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): n   #表示增加分区
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p): p     # 创建主分区
Partition number (3,4, default 3): 3
First sector (52428800-104857599, default 52428800):
Using default value 52428800
Last sector, +sectors or +size{K,M,G} (52428800-104857599, default 104857599):
Using default value 104857599
Partition 3 of type Linux and of size 25 GiB is set

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.

查看当前分区情况:

[root@Agile936 ~]# 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: 0x000f0195

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    52428799    25164800   8e  Linux LVM
/dev/sda3        52428800   104857599    26214400   83  Linux

Disk /dev/mapper/centos-root: 23.6 GB, 23613931520 bytes, 46120960 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

可以看到/dev/sda3的Id号为83，我们要将其改成8e(LVM卷文件系统的Id)，具体方法同上，如下图所示：

[root@Agile936 ~]# 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): 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): 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.

重启后,查看最新的分区,修改成功

[root@Agile936 ~]# 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: 0x000f0195

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    52428799    25164800   8e  Linux LVM
/dev/sda3        52428800   104857599    26214400   8e  Linux LVM

Disk /dev/mapper/centos-root: 23.6 GB, 23613931520 bytes, 46120960 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

3、扩展文件系统

将该分区创建为文件系统：

[root@Agile936 ~]# mkfs.ext4 /dev/sda3
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1638400 inodes, 6553600 blocks
327680 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2155872256
200 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
	4096000

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

创建PV:

pvdisplay当前的物理卷

[root@Agile936 ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               <24.00 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              6143
  Free PE               1
  Allocated PE          6142
  PV UUID               WjHxHP-WmJh-MXl7-qixZ-EGJY-pFxb-MeJK88

pvcreate指令用于将物理硬盘分区初始化为物理卷，以便被LVM使用。要创建物理卷必须首先对硬盘进行分区，并且将硬盘分区的类型设置为“8e”后，才能使用pvcreat指令将分区初始化为物理卷。

[root@Agile936 ~]# pvcreate /dev/sda3
WARNING: ext4 signature detected on /dev/sda3 at offset 1080. Wipe it? [y/n]: y
  Wiping ext4 signature on /dev/sda3.
  Physical volume "/dev/sda3" successfully created.
[root@Agile936 ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos
  PV Size               <24.00 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              6143
  Free PE               1
  Allocated PE          6142
  PV UUID               WjHxHP-WmJh-MXl7-qixZ-EGJY-pFxb-MeJK88

  "/dev/sda3" is a new physical volume of "25.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sda3
  VG Name
  PV Size               25.00 GiB
  Allocatable           NO
  PE Size               0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               lM84VY-OQEa-qwf3-OyO6-W4bm-UNxk-Az6wRb

扩展VG:

当前需要扩充的lvm组名，可以通过vgdisplay查看：

[root@Agile936 ~]# 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               <24.00 GiB
  PE Size               4.00 MiB
  Total PE              6143
  Alloc PE / Size       6142 / 23.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               FWHNlT-utQu-jqv5-ukto-POcw-YOY5-9thDL8

vgextend指令用于动态的扩展卷组，它通过向卷组中添加物理卷来增加卷组的容量,可以看出可扩展的空间为24GB，接下来进行LV扩展，扩展空间要小于VG 的Free PE的大小，即小于24GB。

[root@Agile936 ~]# vgextend centos /dev/sda3
  Volume group "centos" successfully extended
[root@Agile936 ~]# 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               48.99 GiB
  PE Size               4.00 MiB
  Total PE              12542
  Alloc PE / Size       6142 / 23.99 GiB
  Free  PE / Size       6400 / 25.00 GiB
  VG UUID               FWHNlT-utQu-jqv5-ukto-POcw-YOY5-9thDL8

lvextend命令用于扩展空间，如下面将root分区扩展22GB。

[root@Agile936 ~]# lvextend -L +22G /dev/mapper/centos-root
  Size of logical volume centos/root changed from 21.99 GiB (5630 extents) to 43.99 GiB (11262 extents).
  Logical volume centos/root successfully resized.

命令使系统重新读取大小, 添加成功

[root@Agile936 ~]# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1441280 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=5765120, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2815, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 5765120 to 11532288
[root@Agile936 ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   44G  4.2G   40G  10% /
devtmpfs                 2.0G     0  2.0G   0% /dev
tmpfs                    2.0G     0  2.0G   0% /dev/shm
tmpfs                    2.0G  8.6M  2.0G   1% /run
tmpfs                    2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/sda1               1014M  143M  872M  15% /boot
tmpfs                    407M     0  407M   0% /run/user/0