問題描述：根目錄空間佔用率100%

首先用傳統resize2fs方式調整分割槽：

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.

報錯原因是因為檔案系統是xfs（fdisk -l檢視），不再支援resize2fs

解決思路：

①確認分割槽型別為lvm

②檢視到home分割槽有大量閒置空間，決定將home的空間分配給 /

解除安裝home >> 刪除home >> 將home的空間新增到 " / " >> 重新分配home >> 格式化home >> 完成

會用到的命令：

df -h　　　　　　 # 檢視磁碟空間

lsblk　　　　　　　# 檢視塊裝置詳情

fdisk -l # 檢視分割槽詳情

lvremove\lvcreate # 邏輯卷刪除/建立

lvdisplay\vgdisplay\pvdisplay #檢視邏輯卷/卷組/物理卷

xfs_growfs # 載入xfs_growfs

操作過程：

1、分析：檢視分割槽詳情，看到sda2為lvm邏輯卷，所以可以通過將home的空間轉移到根分割槽

# 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備份

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

3、umount解除安裝

# 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，則使用fuser解除佔用
# fuser -m -v -i -k /home

4、刪除home邏輯卷（lv），將home的空間騰出來到卷組（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、重新調整 / 的大小

# lvextend -L 250G /dev/mapper/centos-root  # 調整到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重新整理

# 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、將剩下的空間重新劃分到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.

建立完成別忘了格式化

# 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並檢視

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

8、完成

9、別忘了把home備份還原