Linux系统系统盘扩容

　　在Linux学习过程中，可能会遇到根目录存储空间不足的问题，这时候如果只是新增一块硬盘并挂载到某个目录上，还需要将数据转移至新的硬盘中才能缓解存储压力。这种操作未免有些繁琐，那可不可以直接对跟目录进行扩容呢？当然是可以的，接下来就给大家介绍操作步骤：

　　实验环境：RHEL7系统（默认已部署LVM）、VMware Workstation 12虚拟软件

　　第1步：给虚拟机新增一块20GB的硬盘

　　第2步：查看系统盘的分区类型，最后记得输入q不保存退出

[root@linuxprobe ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.).

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

Command (m for help): p      //输入p查看分区信息

Disk /dev/sda: 21.5 GB,  bytes,  sectors
Units = sectors of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk label type: dos
Disk identifier: 0x00091636

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *                        Linux
/dev/sda2                    8e  Linux LVM    //分区类型为Linux LVM

　Command (m for help): q     //输入q不保存退出

　　第3步：对新硬盘进行分区，并设置分区类型

[root@linuxprobe ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.).

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

Command (m for help): n    //添加一个新分区
Partition type:
   p   primary ( primary,  extended,  free)
   e   extended
Select (default p): p    //主分区
Partition number (-, default ): 1    //分区编号为1
First sector (-, default ): <此处按下回车键>
Using default value
Last sector, +sectors or +size{K,M,G} (-, default ): +10G    //分区大小为10GB
Partition  of type Linux and of size  GiB is set

Command (m for help): p    //再次查看分区信息

Disk /dev/sdb: 21.5 GB,  bytes,  sectors
Units = sectors of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk label type: dos
Disk identifier: 0x1894a517

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1                         Linux     //新的分区添加成功，不过分区类型不对

Command (m for help): t   //变更分区的类型
Selected partition
Hex code (type L to list all codes): 8e    //输入8e即"Linux LVM"
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p     //再次查看分区信息

Disk /dev/sdb: 21.5 GB,  bytes,  sectors
Units = sectors of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk label type: dos
Disk identifier: 0x1894a517

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1                       8e  Linux LVM   //分区类型变更成功，与系统分区一致

Command (m for help): w      //最后记得要保存退出
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

　　第4步：让新添加的硬盘分区支持LVM技术

[root@linuxprobe ~]# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created

　　第5步：查看当前系统的卷组，并将/dev/sdb1硬盘分区加入到卷组中

[root@linuxprobe ~]# vgdisplay
  --- Volume group ---
  VG Name               rhel    //卷组名为"rhel"
  System ID
  Format                lvm2
  Metadata Areas
  Metadata Sequence No
  VG Access             read/write
  VG Status             resizable
  MAX LV
  Cur LV
  Open LV
  Max PV
  Cur PV
  Act PV                
  VG Size               19.51 GiB     //卷组的总容量大小
  PE Size               4.00 MiB
  Total PE
  Alloc PE / Size        / 19.51 GiB
  Free  PE / Size        /
  VG UUID               mGomiV-U0sF-wKii-YxOh-V7Gw-VEQ4-yIkcRD
[root@linuxprobe ~]# vgextend rhel /dev/sdb1         //把/dev/sdb1硬盘分区加入到rhel卷组中
  Volume group "rhel" successfully extended
[root@linuxprobe ~]# vgdisplay
  --- Volume group ---
  VG Name               rhel
  System ID
  Format                lvm2
  Metadata Areas
  Metadata Sequence No
  VG Access             read/write
  VG Status             resizable
  MAX LV
  Cur LV
  Open LV
  Max PV
  Cur PV
  Act PV                
  VG Size               29.50 GiB      //卷组的容量增大了10GB
  PE Size               4.00 MiB
  Total PE
  Alloc PE / Size        / 19.51 GiB
  Free  PE / Size        / 10.00 GiB
  VG UUID               mGomiV-U0sF-wKii-YxOh-V7Gw-VEQ4-yIkcRD

　　第6步：查看当前逻辑卷信息

[root@linuxprobe ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/rhel/swap    //用来充当SWAP分区，我们这里不管它
  LV Name                swap
  VG Name                rhel
  LV UUID                d2gNWI-6Oin-9Q3r-OGLp-0nf5-0Dun-Z8EvgS
  LV Write Access        read/write
  LV Creation host, time localhost, -- :: +
  LV Status              available
  # open
  LV Size                2.00 GiB
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

  --- Logical volume ---
  LV Path                /dev/rhel/root   //该逻辑卷实际就是Linux系统盘，我们将对它进行扩容
  LV Name                root     //逻辑卷名为root
  VG Name                rhel
  LV UUID                rI6Xvu-eCJx-0WFO-TuUj-LQWM-WuUc-3uE6zc
  LV Write Access        read/write
  LV Creation host, time localhost, -- :: +
  LV Status              available
  # open                 
  LV Size                17.51 GiB   //逻辑卷的大小，即系统盘大小
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

　　第7步：对root逻辑卷进行扩容操作

[root@linuxprobe ~]# lvextend -L +10G /dev/rhel/root
  Extending logical volume root to 27.51 GiB
  Insufficient free space:  extents needed, but only  available   //显示实际空闲容量不足10GB，比10GB稍微小一点点
[root@linuxprobe ~]# lvextend -L +5G /dev/rhel/root    //这里我们先扩容5GB
  Extending logical volume root to 22.51 GiB
  Logical volume root successfully resized
[root@linuxprobe ~]# lvdisplay 

----------------省略部分输出内容------------------------

  --- Logical volume ---
  LV Path                /dev/rhel/root
  LV Name                root
  VG Name                rhel
  LV UUID                rI6Xvu-eCJx-0WFO-TuUj-LQWM-WuUc-3uE6zc
  LV Write Access        read/write
  LV Creation host, time localhost, -- :: +
  LV Status              available
  # open                 
  LV Size                22.51 GiB   //容量已从17.51GB提升至22.51GB
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

　　第8步：重置root逻辑卷的大小。xfs系统不需要先umount操作

[root@linuxprobe ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   18G  .1G   15G  % /           //重置之前，先查看当前系统盘的大小，此时显示为18GB
devtmpfs               985M       985M   % /dev
tmpfs                  994M   80K  994M   % /dev/shm
tmpfs                  994M  8.9M  986M   % /run
tmpfs                  994M       994M   % /sys/fs/cgroup
/dev/sr0               .5G  .5G      % /media/cdrom
/dev/sda1              497M  119M  379M  % /boot
[root@linuxprobe ~]# xfs_growfs /dev/rhel/root        //重置root逻辑卷大小
meta-data=/dev/mapper/rhel-root  isize=    agcount=, agsize= blks
         =                       sectsz=   attr=, projid32bit=
         =                       crc=
data     =                       bsize=   blocks=, imaxpct=
         =                       sunit=      swidth= blks
naming   =version               bsize=   ascii-ci= ftype=
log      =internal               bsize=   blocks=, version=
         =                       sectsz=   sunit= blks, lazy-count=
realtime =none                   extsz=   blocks=, rtextents=
data blocks changed from  to
[root@linuxprobe ~]# df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   23G  .1G   20G  % /       //系统盘成功扩容至23G，增加了5GB容量，且重启依然生效
devtmpfs               985M       985M   % /dev
tmpfs                  994M   80K  994M   % /dev/shm
tmpfs                  994M  8.9M  986M   % /run
tmpfs                  994M       994M   % /sys/fs/cgroup
/dev/sr0               .5G  .5G      % /media/cdrom
/dev/sda1              497M  119M  379M  % /boot

　至此，Linux系统盘扩容操作完毕。

　知识补充：

　　1、重置逻辑卷命令 "xfs_growfs /dev/rhel/root" 和 "xfs_growfs /dev/mapper/rhel-root" 效果一样；

　　2、如果是ext4文件系统，重置命令为"resize2fs /dev/rhel/root"；

　　3、xfs文件系统只能扩容，不允许缩容。

[root@linuxprobe ~]# pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/sda2  rhel lvm2 a--  .51g
  /dev/sdb1  rhel lvm2 a--  .00g .00g      //还省5GB空闲容量