背景
自己在家里老笔记搭建的CentOS7系统用来跑一些服务，前段时间通过samba共享存储把小米摄像头视频进行实时转存到笔记本上，最近发现磁盘不足了，因为我默认是挂载到根目录下的，以前安装操作系统时把所有空间分配给了/home目录下，现在根目录的磁盘空间，又不想更改目录，所以打算把/home目录的空间腾出挂载给根目录，于是有了本篇文章。
准备工作
查看当前磁盘分配：
代码语言：javascript复制[root@lcrycentos7 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 1.7G 0 1.7G 0% /dev
tmpfs tmpfs 1.7G 0 1.7G 0% /dev/shm
tmpfs tmpfs 1.7G 170M 1.6G 10% /run
tmpfs tmpfs 1.7G 0 1.7G 0% /sys/fs/cgroup
/dev/mapper/centos_centos7-root xfs 50G 28G 23G 55% /
/dev/sda1 xfs 1014M 311M 704M 31% /boot
/dev/mapper/centos_centos7-home xfs 411G 33M 411G 1% /home
overlay overlay 50G 28G 23G 55% /var/lib/docker/overlay2/0e259cb791ddad0681ebfd184c6408ed5078d362c54b9a9a0815c6edc1f98cf7/merged
tmpfs tmpfs 347M 0 347M 0% /run/user/0- 确认 /home 挂载点的文件系统路径
/dev/mapper/centos_centos7-home所对应的卷组 centos 和逻辑卷 home - 确认 / 挂载点的文件系统路径
/dev/mapper/centos_centos7-root所对应的卷组 centos 和逻辑卷 root - Centos系统默认是xfs文件系统，且xfs文件系统只能扩容不能缩减，在必须缩减逻辑卷容量的前提下，需要使用
xfsdump/xfsrestore进行备份和还原
扩缩容操作
备份 /home 挂载点内容
代码语言：javascript复制## 若没有先安装工具
[root@lcrycentos7 ~]# yum -y install xfsdump
[root@lcrycentos7 ~]# xfsdump -f /home.xfsdump /home
xfsdump: using file dump (drive_simple) strategy
xfsdump: version 3.1.7 (dump format 3.0) - type ^C for status and control
============================= dump label dialog ==============================
please enter label for this dump session (timeout in 300 sec)
-> home
session label entered: "home"
--------------------------------- end dialog ---------------------------------
xfsdump: level 0 dump of lcrycentos7:/home
xfsdump: dump date: Sat Apr 16 10:44:14 2022
xfsdump: session id: 44b0f62a-7a5d-40bd-aecb-23b588e7d01f
xfsdump: session label: "home"
xfsdump: ino map phase 1: constructing initial dump list
xfsdump: ino map phase 2: skipping (no pruning necessary)
xfsdump: ino map phase 3: skipping (only one dump stream)
xfsdump: ino map construction complete
xfsdump: estimated dump size: 20800 bytes
xfsdump: /var/lib/xfsdump/inventory created
============================= media label dialog =============================
please enter label for media in drive 0 (timeout in 300 sec)
-> home
media label entered: "home"
--------------------------------- end dialog ---------------------------------
xfsdump: creating dump session media file 0 (media 0, file 0)
xfsdump: dumping ino map
xfsdump: dumping directories
xfsdump: dumping non-directory files
xfsdump: ending media file
xfsdump: media file size 21352 bytes
xfsdump: dump size (non-dir files) : 0 bytes
xfsdump: dump complete: 11 seconds elapsed
xfsdump: Dump Summary:
xfsdump: stream 0 /home.xfsdump OK (success)
xfsdump: Dump Status: SUCCESS成功备份后，卸载 /home 挂载点
代码语言：javascript复制[root@lcrycentos7 ~]# umount /home减少 /home 挂载点对应的逻辑卷大小
代码语言：javascript复制[root@lcrycentos7 ~]# lvreduce -L 80G /dev/mapper/centos_centos7-home
WARNING: Reducing active logical volume to 80.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce centos_centos7/home? [y/n]: y
Size of logical volume centos_centos7/home changed from <411.13 GiB (105249 extents) to 80.00 GiB (20480 extents).
Logical volume centos_centos7/home successfully resized.增加 / 挂载点对应的逻辑卷大小（将卷组中的空闲空间全部扩展到根分区逻辑卷）
代码语言：javascript复制[root@lcrycentos7 ~]# lvextend -l 100%FREE /dev/mapper/centos_centos7-root
Size of logical volume centos_centos7/root changed from 50.00 GiB (12800 extents) to 381.13 GiB (97570 extents).
Logical volume centos_centos7/root successfully resized.注：这个是分配所有可用空间给根目录，也可以使用
lvextend -r -L 200G /dev/mapper/centos_centos7-root命令指定大小。 -L：指定逻辑卷的大小，单位为“kKmMgGtT”字节； -l：指定逻辑卷的大小（LE数）。
执行扩容生效
代码语言：javascript复制[root@lcrycentos7 ~]# xfs_growfs /dev/mapper/centos_centos7-root
meta-data=/dev/mapper/centos_centos7-root isize=512 agcount=4, agsize=3276800 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=13107200, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
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 99911680格式化 /home 挂载点对应的逻辑卷
代码语言：javascript复制[root@lcrycentos7 ~]# mkfs.xfs -f /dev/mapper/centos_centos7-home
meta-data=/dev/mapper/centos_centos7-home isize=512 agcount=4, agsize=5242880 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=20971520, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=10240, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0重新挂载 /home
代码语言：javascript复制[root@lcrycentos7 ~]# mount /home恢复备份内容到 /home 挂载点
代码语言：javascript复制[root@lcrycentos7 ~]# xfsrestore -f /home.xfsdump /home
xfsrestore: using file dump (drive_simple) strategy
xfsrestore: version 3.1.7 (dump format 3.0) - type ^C for status and control
xfsrestore: searching media for dump
xfsrestore: examining media file 0
xfsrestore: dump description:
xfsrestore: hostname: lcrycentos7
xfsrestore: mount point: /home
xfsrestore: volume: /dev/mapper/centos_centos7-home
xfsrestore: session time: Sat Apr 16 10:44:14 2022
xfsrestore: level: 0
xfsrestore: session label: "home"
xfsrestore: media label: "home"
xfsrestore: file system id: af18ea4a-cd62-4d8f-a1ac-752b805e20db
xfsrestore: session id: 44b0f62a-7a5d-40bd-aecb-23b588e7d01f
xfsrestore: media id: 9cf7c8b3-b948-4535-8750-097a66ccd991
xfsrestore: using online session inventory
xfsrestore: searching media for directory dump
xfsrestore: reading directories
xfsrestore: 1 directories and 0 entries processed
xfsrestore: directory post-processing
xfsrestore: restore complete: 0 seconds elapsed
xfsrestore: Restore Summary:
xfsrestore: stream 0 /home.xfsdump OK (success)
xfsrestore: Restore Status: SUCCESS检查扩容是否升级
代码语言：javascript复制[root@lcrycentos7 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 1.7G 0 1.7G 0% /dev
tmpfs tmpfs 1.7G 0 1.7G 0% /dev/shm
tmpfs tmpfs 1.7G 170M 1.6G 10% /run
tmpfs tmpfs 1.7G 0 1.7G 0% /sys/fs/cgroup
/dev/mapper/centos_centos7-root xfs 382G 28G 354G 8% /
/dev/sda1 xfs 1014M 311M 704M 31% /boot
overlay overlay 382G 28G 354G 8% /var/lib/docker/overlay2/0e259cb791ddad0681ebfd184c6408ed5078d362c54b9a9a0815c6edc1f98cf7/merged
tmpfs tmpfs 347M 0 347M 0% /run/user/0
/dev/mapper/centos_centos7-home xfs 80G 33M 80G 1% /home最后为了保险起见重启服务器再检查一遍
参考
CentOS根目录存储容量调整大小 Ubuntu 20.04.3-live-server 磁盘如何扩容
