问题描述：根目录空间占用率100%

首先用传统resize2fs方式调整分区：

resize2fs -p /dev/mapper/centos-home 50G
resize2fs 1.42.9 (28-Dec-2013)
resize2fs: Bad magic number in super-block while trying to open /dev/mapper/centos-home
Couldn't find valid filesystem superblock.

报错原因是因为文件系统是xfs（fdisk -l查看），不再支持resize2fs

解决思路：

①确认分区类型为lvm

②查看到home分区有大量闲置空间，决定将home的空间分配给 /

卸载home  >>  删除home  >>  将home的空间添加到 " / "   >>   重新分配home  >>   格式化home  >> 完成

会用到的命令：

df -h　　　　　　   # 查看磁盘空间

lsblk　　　　　　　# 查看块设备详情

fdisk -l                      # 查看分区详情

lvremove\lvcreate    # 逻辑卷删除/创建

lvdisplay\vgdisplay\pvdisplay   #查看逻辑卷/卷组/物理卷

xfs_growfs               # 加载xfs_growfs

操作过程：

1、分析：查看分区详情，看到sda2为lvm逻辑卷，所以可以通过将home的空间转移到根分区

# lsblk
NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
fd0               2:0    1     4K  0 disk
sda               8:0    0   300G  0 disk
├─sda1            8:1    0   500M  0 part /boot
└─sda2            8:2    0 299.5G  0 part
  ├─centos-root 253:0    0    50G  0 lvm  /
  ├─centos-swap 253:1    0   9.8G  0 lvm  [SWAP]
  └─centos-home 253:2    0 239.6G  0 lvm  /home
sr0              11:0    1  1024M  0 rom

2、/home备份

# mkdir /tmp/home
# cp -r /home/* /tmp/home

3、umount卸载

# umount /home
umount: /home: target is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

# 如果提示busy，则使用fuser解除占用
# fuser -m -v -i -k /home

4、删除home逻辑卷（lv），将home的空间腾出来到卷组（vg）

# lvremove /dev/mapper/centos-home
Do you really want to remove active logical volume home? [y/n]: y
  Logical volume "home" successfully removed

5、重新调整 / 的大小

# lvextend -L 250G /dev/mapper/centos-root  # 调整到250G
  Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 250.00 GiB (64000 extents).
  Logical volume root successfully resized.

xfs_growfs刷新

# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=256    agcount=4, agsize=3276800 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=0        finobt=0
data     =                       bsize=4096   blocks=13107200, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=0
log      =internal               bsize=4096   blocks=6400, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 13107200 to 65536000

6、将剩下的空间重新划分到home中

# lvcreate -l +100%free -n home centos         # -n 指定lv的名字，centos是vg的名字   
  Logical volume "home" created.

创建完成别忘了格式化

# mkfs.xfs /dev/centos/home
meta-data=/dev/centos/home       isize=256    agcount=4, agsize=2601472 blks
         =                       sectsz=4096  attr=2, projid32bit=1
         =                       crc=0        finobt=0
data     =                       bsize=4096   blocks=10405888, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=0
log      =internal log           bsize=4096   blocks=5081, version=2
         =                       sectsz=4096  sunit=1 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

7、重新mount并查看

# mount /dev/mapper/centos-home /home

8、完成

9、别忘了把home备份还原