linux如何无损调整分区大小

情况：

1. home：500g
2. root：50g
3. root分区不够用

思路：把home分区的空间划一部分到root分区

# 设置home分区大小为200g，释放300g空间
$ lvreduce -l 200g /dev/centos/home

# 将空闲空间扩展到root分区
$ lvextend -l +100%free /dev/centos/root

# 使用xfs文件系统自带的命令集增加分区空间
$ xfs_growfs /dev/mapper/centos-root

实例

situation

挂载在根目录的分区 /dev/mapper/centos-root 爆满，占用100%

$ df -h
filesystem        size used avail use% mounted on
/dev/mapper/centos-root  50g  50g  19m 100% /
devtmpfs         32g   0  32g  0% /dev
tmpfs           32g   0  32g  0% /dev/shm
tmpfs           32g 2.5g  29g  8% /run
tmpfs           32g   0  32g  0% /sys/fs/cgroup
/dev/mapper/centos-home 476g  33m 476g  1% /home
/dev/sda1        497m 238m 259m 48% /boot
tmpfs          6.3g   0 6.3g  0% /run/user/0

analyze

挂载在根目录的分区空间太小，只有50g，而服务器 home 目录为非常用目录，挂在了近500g的空间。

思路：从 centos-home 分区划出300g空间到 centos-root 分区。

operation

1.查看各分区信息

$ lvdisplay
--- logical volume ---
lv path        /dev/centos/home
lv name        home
vg name        centos
lv uuid        1fat1e-bqsa-1hxr-mce2-5vz1-xzbz-ii1slv
lv write access    read/write
lv creation host, time localhost, 2016-10-26 17:23:47 +0800
lv status       available
# open         0
lv size        475.70 gib
current le       121778
segments        1
allocation       inherit
read ahead sectors   auto
- currently set to   256
block device      253:2

--- logical volume ---
lv path        /dev/centos/root
lv name        root
vg name        centos
lv uuid        ld64zy-yc3z-szab-dajk-03ym-2gm8-pfj4oo
lv write access    read/write
lv creation host, time localhost, 2016-10-26 17:23:48 +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   256
block device      253:0

2.减少/home分区空间

# 释放 /dev/centos/home 分区 300g 的空间
# 命令设置 /dev/centos/home 分区 200g空间
$ lvreduce -l 200g /dev/centos/home
warning: reducing active logical volume to 200.00 gib.
 this may destroy your data (filesystem etc.)
do you really want to reduce centos/home? [y/n]: y
 size of logical volume centos/home changed from 475.70 gib (121778 extents) to 200.00 gib (51200 extents).
 logical volume centos/home successfully resized.

3.增加/root分区空间

$ lvextend -l +100%free /dev/centos/root
size of logical volume centos/root changed from 50.06 gib (12816 extents) to 325.76 gib (83394 extents).
logical volume centos/root successfully resized.

4.扩展xfs文件空间大小

$ xfs_growfs /dev/mapper/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 85395456

完成

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