详解基于Linux的LVM无缝磁盘水平扩容

环境

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 lvmlvm2-libs-2.02.118-2.el6.x86_64lvm2-2.02.118-2.el6.x86_64[root@Candy ~]# lvlvchange   lvextend   lvmdiskscan lvmsar    lvresizelvconvert  lvm     lvmdump   lvreduce   lvslvcreate   lvmchange  lvmetad   lvremove   lvscanlvdisplay  lvmconf   lvmsadc   lvrename[root@Candy ~]# rpm -qa | grep partedparted-2.1-29.el6.x86_64

软件准备好后顺便查看下 VM 硬件:

[root@Candy ~]# df -hFilesystem      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 -lDisk /dev/sda: 21.5 GB, 21474836480 bytes255 heads, 63 sectors/track, 2610 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x0006e71c  Device Boot   Start     End   Blocks  Id System/dev/sda1  *      1     64   512000  83 LinuxPartition 1 does not end on cylinder boundary./dev/sda2       64    2611  20458496  8e Linux LVMDisk /dev/sdb: 4398.0 GB, 4398046511104 bytes255 heads, 63 sectors/track, 534698 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000Disk /dev/mapper/vg_candy-root: 8061 MB, 8061452288 bytes255 heads, 63 sectors/track, 980 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000Disk /dev/mapper/vg_candy-usr: 4294 MB, 4294967296 bytes255 heads, 63 sectors/track, 522 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000Disk /dev/mapper/vg_candy-var: 4294 MB, 4294967296 bytes255 heads, 63 sectors/track, 522 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000Disk /dev/mapper/vg_candy-home: 4294 MB, 4294967296 bytes255 heads, 63 sectors/track, 522 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk 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/sdbGNU Parted 2.1使用 /dev/sdbWelcome 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) pModel: VMware, VMware Virtual S (scsi)Disk /dev/sdb: 4398GBSector size (logical/physical): 512B/512BPartition Table: gptNumber Start  End   Size  File system Name 标志 1   1049kB 4398GB 4398GB(parted)set 1 lvm on(parted)pModel: VMware, VMware Virtual S (scsi)Disk /dev/sdb: 4398GBSector size (logical/physical): 512B/512BPartition Table: gptNumber 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/sdb1Physical volume "/dev/sdb1" successfully createdVolume group "vg_candy" successfully extended

现在我们再用vgs命令看一下pv个数:

[root@Candy ~]# vgsVG    #PV #LV #SN Attr  VSize VFreevg_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 -hFilesystem         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 -hFilesystem         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-rootresize2fs 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 = 32Performing 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-usrresize2fs 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 = 32Performing 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-varresize2fs 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 = 32Performing 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-homeresize2fs 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 = 32Performing 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 -hFilesystem          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。