CentOS 7 磁盘扩容

假设已经添加了磁盘,到了需要在系统里操作的步骤

对新增加的硬盘进行分区

fidsk -l
fdisk /dev/sda (根据实际情况选择)
n	(新增加一个分区)
p	(区类型选择为主分区)
回车	(分区号)
回车　（起始扇区）
回车　（结束扇区）
t
上面的分区号
8e 将分区“Linux”的类型更改为“Linux LVM”
w 保存
reboot

对新增加的硬盘格式化

mkfs.ext4 /dev/sda3

添加新LVM到已有的LVM组，实现扩容

lvm　　　　　　　　　　　　 进入lvm管理
lvm> pvcreate /dev/sda3 这是初始化刚才的分区，必须的
lvm>vgextend centos /dev/sda3 将初始化过的分区加入到虚拟卷组vg_dc01
lvm>lvextend -L +100G /dev/mapper/centos-root　　扩展已有卷的容量（注意容量大小）
lvm>pvdisplay　　　　　　　　　　　　　　 查看卷容量，这时你会看到一个很大的卷了
lvm>quit　

以上只是卷扩容了，下面是文件系统的真正扩容，输入以下命令：

resize2fs /dev/mapper/centos-root

resize2fs: Bad magic number in super-block 当尝试打开 /dev/mapper/centos-root 时

报错：当尝试打开 /dev/mapper/centos-root 时 找不到有效的文件系统超级块

因为我的centos7的某些分区用的是xfs的文件系统（使用df -T查看即可知道）

将resize2fs替换为xfs_growfs，重新执行一遍即可，如下：

 xfs_growfs /dev/mapper/centos-root

步骤记录

[root@last ~]# 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): p

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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: 0x000ae200

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   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 (41943040-209715199, default 41943040):
Using default value 41943040
Last sector, +sectors or +size{K,M,G} (41943040-209715199, default 209715199):
Using default value 209715199
Partition 3 of type Linux and of size 80 GiB is set

Command (m for help): p

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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: 0x000ae200

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
/dev/sda3        41943040   209715199    83886080   83  Linux

Command (m for help): t
Partition number (1-3, default 3): 8e
Partition number (1-3, default 3):
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: 107.4 GB, 107374182400 bytes, 209715200 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: 0x000ae200

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
/dev/sda3        41943040   209715199    83886080   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@last ~]#
[root@last ~]# reboot
Connection to 192.168.50.130 closed by remote host.
Connection to 192.168.50.130 closed.
➜  frelon
➜  frelon
➜  frelon ssh root@192.168.50.130
Last login: Sat Sep 19 04:08:59 2020 from 192.168.50.1
[root@last ~]# 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
5242880 inodes, 20971520 blocks
1048576 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2168455168
640 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, 7962624, 11239424, 20480000

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

[root@last ~]#
[root@last ~]#
[root@last ~]# lvm
lvm> 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.
lvm>
lvm> vgextend centos /dev/sda3
  Volume group "centos" successfully extended
lvm> lvextend -L +79G /dev/mapper/centos-root
  Size of logical volume centos/root changed from <17.00 GiB (4351 extents) to <96.00 GiB (24575 extents).
  Logical volume centos/root successfully resized.
lvm> quit
  Exiting.
[root@last ~]# xfs_
xfs_admin      xfs_db         xfs_fsr        xfs_io         xfs_metadump   xfs_quota
xfs_bmap       xfs_estimate   xfs_growfs     xfs_logprint   xfs_mkfile     xfs_repair
xfs_copy       xfs_freeze     xfs_info       xfs_mdrestore  xfs_ncheck     xfs_rtcp
[root@last ~]# xfs_
xfs_admin      xfs_db         xfs_fsr        xfs_io         xfs_metadump   xfs_quota
xfs_bmap       xfs_estimate   xfs_growfs     xfs_logprint   xfs_mkfile     xfs_repair
xfs_copy       xfs_freeze     xfs_info       xfs_mdrestore  xfs_ncheck     xfs_rtcp
[root@last ~]# xfs_growfs /dev/mapper/c
centos-root  centos-swap  control
[root@last ~]# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1113856 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=4455424, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 4455424 to 25164800
[root@last ~]#
[root@last ~]#
[root@last ~]# df -h
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 898M     0  898M   0% /dev
tmpfs                    910M     0  910M   0% /dev/shm
tmpfs                    910M  9.5M  901M   2% /run
tmpfs                    910M     0  910M   0% /sys/fs/cgroup
/dev/mapper/centos-root   96G  1.4G   95G   2% /
/dev/sda1               1014M  150M  865M  15% /boot
tmpfs                    182M     0  182M   0% /run/user/0

　由于在安装centos系统的时候，如果在安装时没有分配磁盘空间，选择的是默认分配的，在安装完成后，可以发现大容量磁盘往往分配在了home下面。

如果要把home下面的磁盘空间分配到root磁盘下面。可以进行如下操作。

1.查看CentOS的系统版本

[root@controller ~]# cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)

2.查看分区

df -h (centos-home和centos-root每人的名字可能不一样)

[root@controller ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        50G  8.5G   42G  17% /
devtmpfs        1.9G     0  1.9G   0% /dev
tmpfs           1.9G     0  1.9G   0% /dev/shm
tmpfs           1.9G  8.7M  1.9G   1% /run
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda6        20G   33M   20G   1% /home
/dev/sda5        26G  804M   26G   4% /var
/dev/sda2       2.0G  125M  1.9G   7% /boot
/dev/loop0      4.1G  4.1G     0 100% /mnt/centos
/dev/loop1      2.7G  2.7G     0 100% /mnt/xiandi
tmpfs           378M     0  378M   0% /run/user/0

3.备份home分区文件

[root@controller ~]# tar cvzf /mnt/home.tar /home/
tar: Removing leading `/' from member names
/home/
/home/frelon/

4.卸载/home，如果无法卸载，先终止使用/home文件系统的进程

[root@controller ~]# umount /home （卸载）

如果卸载时，发现/home在使用中，所以先终止。

[root@controller ~]# fuser -km /home/（终止）

再次卸载，没有报错，表示成功。

[root@controller ~]# umount /home （卸载）

5.删除/home所在的lv

lvremove /dev/mapper/centos-home

6.扩展/root所在的lv

lvextend -L +100G /dev/mapper/centos-root

7.扩展/root文件系统

xfs_growfs /dev/mapper/centos-root

8.重新创建home lv （创建时计算好剩余的磁盘容量，建议比剩余小1G左右）

lvcreate -L 41G -n /dev/mapper/centos-home 

9.创建文件系统

mkfs.xfs /dev/mapper/centos-home

10.挂载home

mount /dev/mapper/centos-home

11.home文件恢复

tar xvf /tmp/home.tar -C /home/

12.再次使用df -h查看系统磁盘大小

可以看到home下面100G的磁盘容量已经转移到root下面了，至此，转移任务结束。此为在CentOS7.2系统下测试使用的，在CentOS6版本下还没测试过。

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