Linux Centos 根目录扩展分区（保级教程）

1. 扩展背景

虚拟机初始分配20G内存，扩容到80G。

2.列出磁盘信息

可以得知容量信息以及即将创建的PV路径（通常为“/dev/sda累加数字”），下面例子为sda2，预期扩展60G

# 列出各分区使用情况
[root@master02 ~]# df -hl
# 查看现有磁盘情况
[root@master02 ~]# fdisk -l
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Disk /dev/sda: 85.9 GB, 85899345920 bytes, 167772160 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000ae5b5

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM

Disk /dev/mapper/centos-root: 18.2 GB, 18249416704 bytes, 35643392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
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3. 对磁盘进行分区

    sudo fdisk /dev/sda(你的磁盘号)
    命令行提示下输入:
  【n】添加新分区。
  【p】创建主分区。
  【回车】分区号  　--默认分区编号 
  【回车】--默认起始扇区位置。
  【回车】--默认结束扇区位置。 如果要把100G全部分给这个分区，直接两次回车。如果分60G输入+60G
  【t】      --修改分区类型
  【8e】   --修改为LVM
  【w】    --保存
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具体操作如下：

[root@master02 ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help):【n】
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p): 【p】
Partition number (3,4, default 3): 【回车】
First sector (41943040-167772159, default 41943040): 【回车】
Using default value 41943040
Last sector, +sectors or +size{K,M,G} (41943040-167772159, default 167772159): 【回车】
Using default value 167772159
Partition 3 of type Linux and of size 60 GiB is set

Command (m for help): t
Partition number (1-3, default 3): 【回车】
Hex code (type L to list all codes): 【8e]
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help):【w】
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

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4. 重启Linux

重启linux，必须reboot，否则无法格式化。

reboot
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5. 将PV加入卷组centos并分区

• 始化PV并加入卷组centos

 pvcreate /dev/sda3
 vgextend centos /dev/sda3
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• 将空余容量分配给逻辑分区
  +60G根据本次要扩展的容量得出，具体数值看分配扩展空间的大小，如果60G空间溢出，可以选择59G

 lvextend -L +60G /dev/mapper/centos-root
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• 重载

xfs_growfs /dev/centos/root
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具体操作步骤如下：

[root@master02 ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                7FxqiT-LSfr-380m-aXO0-i8k4-O7TC-oRxCA0
  LV Write Access        read/write
  LV Creation host, time localhost, 2023-11-10 18:42:59 +0800
  LV Status              available
  # open                 2
  LV Size                2.00 GiB
  Current LE             512
  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                2MCadI-YApB-DtaL-a8uo-eubT-SwzJ-CYvmif
  LV Write Access        read/write
  LV Creation host, time localhost, 2023-11-10 18:42:59 +0800
  LV Status              available
  # open                 1
  LV Size                <17.00 GiB
  Current LE             4351
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
   
[root@master02 ~]# lvextend -L +60G /dev/mapper/centos-root
  Insufficient free space: 15360 extents needed, but only 15359 available
[root@master02 ~]# lvextend -L +59G /dev/mapper/centos-root
  Size of logical volume centos/root changed from <17.00 GiB (4351 extents) to <76.00 GiB (19455 extents).
  Logical volume centos/root successfully resized.
[root@master02 ~]# xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1113856 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=4455424, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 4455424 to 19921920
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6.查看分区结果

/dev/mapper/centos-root已经扩展到75G

[root@master02 ~]# df -hl
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 1.4G     0  1.4G   0% /dev
tmpfs                    1.4G     0  1.4G   0% /dev/shm
tmpfs                    1.4G   11M  1.4G   1% /run
tmpfs                    1.4G     0  1.4G   0% /sys/fs/cgroup
/dev/mapper/centos-root   76G  4.6G   72G   7% /
/dev/sda1               1014M  223M  792M  22% /boot
tmpfs                    283M   24K  283M   1% /run/user/1001
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