详解基于Linux的LVM无缝磁盘水平扩容

环境

名称	属性
cpu	x5650
内存	4g
磁盘	20g+4tb

 

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

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

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

现在让我们来解释一下操作：

1. 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）
2. 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。
3. 输入p 打印出刚才才做后生成的分区。
4. 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 ~]#

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

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

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

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

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

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

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

结束语

顺便给大家晒一张重启后系统自动挂载的图！

linux系统还是比较聪明的. 其实重启与不重启都能使用, 只是为大家演示重启后的效果.

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。