基于Linux的LVM无缝磁盘水平扩容

栏目: 后端 · 发布时间: 4年前

内容简介：这时候，我们假设服务器已经有如下东西：首先查看软件是否安装：软件准备好后顺便查看下 VM 硬件:

名称	属性
CPU	x5650
内存	4G
磁盘	20G+4TB

基于 <a href='https://www.codercto.com/topics/18170.html'>Linux</a> 的LVM无缝磁盘水平扩容

这时候，我们假设服务器已经有如下东西：

安装好了Parted（yum install parted）
分区容量已经告捷，公司为服务器增加了一块4T硬盘用来增加容量！
除了/boot分区外，其余都为LVM 模式的扩展逻辑分区

软件安装与信息查看

首先查看软件是否安装：

[root@Candy ~]# rpm -qa | grep lvm
lvm2-libs-2.02.118-2.el6.x86_64
lvm2-2.02.118-2.el6.x86_64
[root@Candy ~]# lv
lvchange     lvextend     lvmdiskscan  lvmsar       lvresize
lvconvert    lvm          lvmdump      lvreduce     lvs
lvcreate     lvmchange    lvmetad      lvremove     lvscan
lvdisplay    lvmconf      lvmsadc      lvrename
[root@Candy ~]# rpm -qa | grep parted
parted-2.1-29.el6.x86_64
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软件准备好后顺便查看下 VM 硬件:

[root@Candy ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_candy-root
                      7.3G  231M  6.7G   4% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             477M   30M  422M   7% /boot
/dev/mapper/vg_candy-home
                      3.9G  8.0M  3.7G   1% /home
/dev/mapper/vg_candy-usr
                      3.9G  382M  3.3G  11% /usr
/dev/mapper/vg_candy-var
                      3.9G   63M  3.6G   2% /var
[root@Candy ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0006e71c
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2611    20458496   8e  Linux LVM
Disk /dev/sdb: 4398.0 GB, 4398046511104 bytes
255 heads, 63 sectors/track, 534698 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_candy-root: 8061 MB, 8061452288 bytes
255 heads, 63 sectors/track, 980 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_candy-usr: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_candy-var: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_candy-home: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
[root@Candy ~]# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sda2  /dev/sdb
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这时候我们看到，Centos 已经知道有个sdb的盘了，但是没挂载与分区。

使用Parted进行扩容前的分区

现在假设除了/boot 其余分区都满了! 我们需要先进行分区，将4T的硬盘用上(/dev/sdb).

[root@Candy ~]# parted /dev/sdb
GNU Parted 2.1
使用 /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel
新的磁盘标签类型？ gpt
(parted) mkpart
分区名称？  []?
文件系统类型？  [ext2]? ext4
起始点？ 0T
结束点？ 4T
(parted) p
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdb: 4398GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number  Start   End     Size    File system  Name  标志
 1      1049kB  4398GB  4398GB
(parted)set 1 lvm on
(parted)p
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdb: 4398GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number  Start   End     Size    File system  Name  标志
1      1049kB  4398GB  4398GB                      lvm
(parted)q
[root@Candy ~]# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sda2  /dev/sdb  /dev/sdb1
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现在让我们来解释一下操作：

mklabel将磁盘转换为gpt分区，因为MBR分区无法支持TB级硬盘（具体请自行查阅，parted当然也支持TB级以下的操作）
mkpart将转换好的gpt磁盘进行分区，需要提供文件系统类型、开始点、结束点。
输入p 打印出刚才才做后生成的分区。
set 1 lvm on 是将num为1的分区，tager设置为LVM ，这样才能添加到vm卷组里

下一步，我们查看我们的LVM组名叫什么:

[root@Candy ~]# vgs
  VG       #PV #LV #SN Attr   VSize  VFree
  vg_candy   1   4   0 wz--n- 19.51g    0
  
[root@Candy ~]# vgdisplay
  --- Volume group ---
  VG Name               vg_candy
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                4
  Open LV               4
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               19.51 GiB
  PE Size               4.00 MiB
  Total PE              4994
  Alloc PE / Size       4994 / 19.51 GiB
  Free  PE / Size       0 / 0
  VG UUID               Gcm5Ml-fc88-Xk5q-xuPC-Kj7Y-alfK-i770Gc
[root@Candy ~]# lvscan
  ACTIVE            '/dev/vg_candy/usr' [4.00 GiB] inherit
  ACTIVE            '/dev/vg_candy/var' [4.00 GiB] inherit
  ACTIVE            '/dev/vg_candy/home' [4.00 GiB] inherit
  ACTIVE            '/dev/vg_candy/root' [7.51 GiB] inherit
[root@Candy ~]#
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知道lvm卷组叫 'vg_candy'了, 我们就使用vgextend来向lvm 'vg_candy' 卷组添加成员了.

[root@Candy ~]# vgextend vag_candy /dev/sdb1
Physical volume "/dev/sdb1" successfully created
Volume group "vg_candy" successfully extended
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现在我们再用vgs命令看一下pv个数:

[root@Candy ~]# vgs
VG       #PV #LV #SN Attr   VSize VFree
vg_candy   2   4   0 wz--n- 4.02t 4.00t
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大家对比未添加时的vgs是否有看到PV个数从1变为2了！

现在让我们用vgdisplay看看现在分区的容量.

[root@Candy ~]# vgdisplay
  --- Volume group ---
  VG Name               vg_candy
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  6
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                4
  Open LV               4
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               4.02 TiB
  PE Size               4.00 MiB
  Total PE              1053569
  Alloc PE / Size       4994 / 19.51 GiB
  Free  PE / Size       1048575 / 4.00 TiB
  VG UUID               Gcm5Ml-fc88-Xk5q-xuPC-Kj7Y-alfK-i770Gc
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再次对比未添加的vgdiplay命令发现，FreePE 的value 从 0 / 0 变为 1048575 / 4.00 TiB . 这样说明Candy已经成功将4TB的lvm 分区添加进入到vg_candy 逻辑卷组里了。

现在我们对所有逻辑分区进行扩容前，df -h 看看有哪些分区。

[root@Candy ~]# df -h
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/vg_candy-root  7.3G  231M  6.7G   4%  /
 tmpfs                     1.9G     0  1.9G   0%  /dev/shm
/dev/sda1                  477M   30M  422M   7%  /boot
/dev/mapper/vg_candy-home  3.9G  8.0M  3.7G   1%  /home                 
/dev/mapper/vg_candy-usr   3.9G  382M  3.3G  11%  /usr
/dev/mapper/vg_candy-var   3.9G   63M  3.6G   2%  /var
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现在麻烦的事已经做完了，接下来就剩下为分区进行扩容了.

为磁盘进行扩容

假设：我们需要向这些分区都添加500G容量: / 、 /home 、 /usr 、 /var

[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-root
  Size of logical volume vg_candy/root changed from 7.51 GiB (1922 extents) to 507.51 GiB (129922 extents).
  Logical volume root successfully resized
  
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-home
  Size of logical volume vg_candy/home changed from 4.00 GiB (1024 extents) to 504.00 GiB (129024 extents).
  Logical volume home successfully resized
  
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-usr
  Size of logical volume vg_candy/usr changed from 4.00 GiB (1024 extents) to 504.00 GiB (129024 extents).
  Logical volume usr successfully resized
  
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-var
  Size of logical volume vg_candy/var changed from 4.00 GiB (1024 extents) to 504.00 GiB (129024 extents).
  Logical volume var successfully resized
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大家注意，这一步操作时不可逆的！如果输入了错误的分区名字还好！如果添加到其它分区了，就得重复N遍来缩容，比较麻烦哦！建议大家注仔细核对上面的FileSystem. 切记切记....

提示扩容成功！让我们再次用上述命令查看LVM信息:

[root@Candy ~]# vgs
  VG       #PV #LV #SN Attr   VSize VFree
  vg_candy   2   4   0 wz--n- 4.02t 2.05t 
  
[root@Candy ~]# lvscan
  ACTIVE            '/dev/vg_candy/usr' [504.00 GiB] inherit
  ACTIVE            '/dev/vg_candy/var' [504.00 GiB] inherit
  ACTIVE            '/dev/vg_candy/home' [504.00 GiB] inherit
  ACTIVE            '/dev/vg_candy/root' [507.51 GiB] inherit
  
[root@Candy ~]# vgdisplay
  --- Volume group ---
  VG Name               vg_candy
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  10
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                4
  Open LV               4
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               4.02 TiB
  PE Size               4.00 MiB
  Total PE              1053569
  Alloc PE / Size       516994 / 1.97 TiB
  Free  PE / Size       536575 / 2.05 TiB
  VG UUID               Gcm5Ml-fc88-Xk5q-xuPC-Kj7Y-alfK-i770Gc
  
[root@Candy ~]# df -h
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/vg_candy-root  7.3G  231M  6.7G   4%  /
 tmpfs                     1.9G     0  1.9G   0%  /dev/shm
/dev/sda1                  477M   30M  422M   7%  /boot
/dev/mapper/vg_candy-home  3.9G  8.0M  3.7G   1%  /home                 
/dev/mapper/vg_candy-usr   3.9G  382M  3.3G  11%  /usr
/dev/mapper/vg_candy-var   3.9G   63M  3.6G   2%  /var
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看到这里大家可能奇怪！为什么df -h 还没变呢?

刷新磁盘信息与写入

我们需要用resize2fs 重设分区大小, 这样才能使df -h 也能生效.

而resize2fs 需要的时间与你给予的容量线性叠加. 也就是说你给的容量越多，resize2fs 的需要的时间就越多。

[root@Candy ~]# resize2fs /dev//mapper/vg_candy-root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-root is mounted on /; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-root to 133040128 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-root is now 133040128 blocks long.

[root@Candy ~]# resize2fs /dev//mapper/vg_candy-usr
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-usr is mounted on /usr; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-usr to 132120576 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-usr is now 132120576 blocks long.

[root@Candy ~]# resize2fs /dev//mapper/vg_candy-var
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-var is mounted on /var; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-var to 132120576 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-var is now 132120576 blocks long.

[root@Candy ~]# resize2fs /dev//mapper/vg_candy-home
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-home is mounted on /home; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-home to 132120576 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-home is now 132120576 blocks long.

[root@Candy ~]# df -h
Filesystem                    Size  Used Avail Use%  Mounted on
/dev/mapper/vg_candy-root     500G  245M  474G   1%  /
tmpfs                         1.9G     0  1.9G   0%  /dev/shm
/dev/sda1                     477M   30M  422M   7%  /boot
/dev/mapper/vg_candy-home     496G   16M  471G   1%  /home
/dev/mapper/vg_candy-usr      496G  390M  471G   1%  /usr
/dev/mapper/vg_candy-var      496G   71M  471G   1%  /var
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以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持码农网

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