Linux磁盘分配 把home的空间扩容给root
1 背景
系统用来一段时间后，写入数据发现硬盘空间提示不足，当时感觉很奇怪，我的硬盘是500G，也没有什么大文件，为什么存在硬盘不足的情况呢。一查看硬盘使用情况，发现root分区只有50G，home有450G，现在知道为什么提示硬盘不足了，root分区既然只有50G，为什么root分区只有50G呢？后来在网上查了下才知道，再安装系统的时候，如果不进行操作硬盘分区，默认的情况下，root默认比较小，大部分分区会给home。知道原因了，现在只有想办法把home的空间扩容给root。
2 查看现在的分区情况
利用df -h 显示，centos-home 有442G，centos-root 只有50G
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
devtmpfs 7.8G 0 7.8G 0% /dev
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 7.8G 5.8M 7.8G 1% /run
tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup
/dev/mapper/centos-root 50G 26G 25G 51% / # root 的空间
/dev/sda1 497M 165M 332M 34% /boot
/dev/mapper/centos-home 442G 33M 442G 1% /home # home 的空间
利用vgdisplay 显示，没有空闲的空间
[root@localhost /]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <499.51 GiB
PE Size 4.00 MiB
Total PE 127874
Alloc PE / Size 25056 / <97.88 GiB
Free PE / Size 0 / 0 # 没有空闲的空间
VG UUID CLUqlt-jF82-fC40-de7C-lHA6-78ff-khtCWW
3 从home分区转移出空间
3.1 备份home目录
# 切换到根下
cd /
# 打包home下所有文件
tar -czvf home.tgz home/
# 存放到tmp路径下
mv home.tgz /tmp
3.2 卸载home目录
# 杀掉home下的所有进程（不杀进程后边卸载会报错）如果提示fuser命令不存在，就安装fuser：yum -y install psmisc
fuser -km /home/
# 卸载home
umount /home
# 删除逻辑卷
lvremove /dev/centos/home
利用vgdisplay 显示，空闲空间401G
[root@localhost /]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <499.51 GiB
PE Size 4.00 MiB
Total PE 127874
Alloc PE / Size 25056 / <97.88 GiB
Free PE / Size 102818 / 401.63 GiB # 空闲空间401G
VG UUID CLUqlt-jF82-fC40-de7C-lHA6-78ff-khtCWW
3.3 从新就home分区并且还原home
# 创建新的home卷，并分配空间。
# L表示大小，默认单位为M；n表示卷名；这里的centos是CentOS7安装系统的时候就默认建立好的卷组名。
[root@localhost /]# lvcreate -L 40G -n home centos
WARNING: xfs signature detected on /dev/centos/home at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/centos/home.
Logical volume "home" created.
利用vgdisplay 显示，home分区为40G
[root@localhost /]# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID nvewrv-rB8K-K1oW-jrWo-8aRU-Li2N-PNd0Uv
LV Write Access read/write
LV Creation host, time localhost, 2022-11-03 15:22:30 +0800
LV Status available
# open 2
LV Size <7.88 GiB
Current LE 2016
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID J3pQhK-l2WV-ps3V-AVs5-EZ2H-1Ebs-xcOCcS
LV Write Access read/write
LV Creation host, time localhost, 2022-11-03 15:22:30 +0800
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/centos/home
LV Name home
VG Name centos
LV UUID s1ApJs-Aaok-KkTb-klfk-Da7p-pVYA-Hy2fzD
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2022-12-02 21:21:16 +0800
LV Status available
# open 1
LV Size 40.00 GiB
Current LE 10240
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
再次查看闲置空间大小：vgdisplay 我这显示还有300多，准备都给到root
[root@localhost /]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <499.51 GiB
PE Size 4.00 MiB
Total PE 127874
Alloc PE / Size 25056 / <97.88 GiB
Free PE / Size 82818 / 361.63 GiB
VG UUID CLUqlt-jF82-fC40-de7C-lHA6-78ff-khtCWW
# 在home上建立xfs文件系统
[root@localhost /]# mkfs -t xfs /dev/centos/home
meta-data=/dev/centos/home isize=512 agcount=4, agsize=2621440 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=10485760, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=5120, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# 挂载home
[root@localhost /]# mount /dev/centos/home /home
# 查看
[root@localhost /]# df -h
文件系统 容量 已用 可用 已用% 挂载点
devtmpfs 7.8G 0 7.8G 0% /dev
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 7.8G 5.8M 7.8G 1% /run
tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup
/dev/mapper/centos-root 50G 26G 25G 51% /
/dev/sda1 497M 165M 332M 34% /boot
overlay 50G 26G 25G 51%
/dev/mapper/centos-home 40G 33M 0G 0% /home # home 的空间
# 解压之前备份的压缩包至home目录
[root@localhost /]# tar -xzvf /tmp/home.tgz -C /home
# 这时会有两层home目录，把里边的内容移动出来：
[root@localhost /]# mv /home/home/* /home/
# 然后删除内部的home目录：
[root@localhost /]# rm -rf /home/home/
4 扩容root
4.1 分配空间给root
# 分配400G空间给root（根据自己的空闲空间决定）
[root@localhost /]# lvextend -L +400G /dev/centos/root
Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 450.00 GiB (115200 extents).
Logical volume centos/root successfully resized.
再次查看闲置空间大小：lvdisplay，root的空间为450G
[root@localhost /]# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID nvewrv-rB8K-K1oW-jrWo-8aRU-Li2N-PNd0Uv
LV Write Access read/write
LV Creation host, time localhost, 2022-11-03 15:22:30 +0800
LV Status available
# open 2
LV Size <7.88 GiB
Current LE 2016
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID J3pQhK-l2WV-ps3V-AVs5-EZ2H-1Ebs-xcOCcS
LV Write Access read/write
LV Creation host, time localhost, 2022-11-03 15:22:30 +0800
LV Status available
# open 1
LV Size 450.00 GiB
Current LE 115200
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/centos/home
LV Name home
VG Name centos
LV UUID s1ApJs-Aaok-KkTb-klfk-Da7p-pVYA-Hy2fzD
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2022-12-02 21:21:16 +0800
LV Status available
# open 1
LV Size 40.00 GiB
Current LE 10240
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
4.2 扩展root 卷XFS 文件系统的大小
# 扩展root 卷XFS 文件系统的大小
[root@localhost /]# xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=256 agcount=4, agsize=3276800 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 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=0
log =internal bsize=4096 blocks=6400, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 13107200 to 117964800
4.3 检查分配结果，大功告成
[root@localhost /]# df -h
文件系统 容量 已用 可用 已用% 挂载点
devtmpfs 7.8G 0 7.8G 0% /dev
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 7.8G 5.8M 7.8G 1% /run
tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup
/dev/mapper/centos-root 450G 26G 425G 6% /
/dev/sda1 497M 165M 332M 34% /boot
overlay 450G 26G 425G 6%
/dev/mapper/centos-home 40G 33M 40G 1% /home