虚拟化逐渐成为我们日常运维工作的主要部署策略。在虚拟化带来的各种好处中，硬件资源动态调整是传统物理机难以企及的优势方面。针对不同类型的应用和性能需求，我们可以为各个应用系统提供更加个性化的部署方案和资源解决方案。而且，当存储、CPU和内存等资源不足的时候，我们是可以快速的提供资源补充给应用。
LVM是一种源自Unix环境，在Linux上广泛应用的逻辑虚拟盘存储方案。借助LVM，可以在保证各个Linux目录分区稳定，又可以实现各目录存储资源灵活分配。
本文主要系统介绍Linux环境下，LVM实现资源扩容步骤方法。留待需要朋友待查。
1、环境介绍
笔者使用Linux 6.5进行测试，背景是一台用于测试搭建的数据库服务器，需要转换为正式投产，但是原有可用根节点空间只有50G左右。
[root@Testserver vg_li6]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_li6-lv_root 50G 20G 27G 43% /
tmpfs 3.9G 232K 3.9G 1% /dev/shm
/dev/sda1 485M 39M 421M 9% /boot
/dev/mapper/vg_li6-lv_home 26G 173M 24G 1% /home
目标是通过外围虚拟化环境，增加存储空间，并且将增加的空间转移到/目录下。也就是增加在vg_li6虚拟磁盘组的lv_root逻辑卷下面。
2、增加磁盘空间和分区
联系负责虚拟化的同事，为虚拟机增加虚拟磁盘sdb。通过fdisk命令，可以比较清晰的查看到。
[root@Testserver ~]# fdisk -l
Disk /dev/sda: 85.9 GB, 85899345920 bytes
255 heads, 63 sectors/track, 10443 cylinders
（篇幅原因，有省略……）
Disk /dev/sdb: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 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
使用fdisk命令进行格式化。
[root@Testserver ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x44e9daf0.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n –创建新的磁盘组
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-13054, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-13054, default 13054):
Using default value 13054
Command (m for help): w –写入磁盘分区信息
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
查看fdisk结果。
[root@Testserver ~]# fdisk -l
Disk /dev/sda: 85.9 GB, 85899345920 bytes
255 heads, 63 sectors/track, 10443 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: 0x00064fe0
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 10444 83373056 8e Linux LVM
（篇幅原因，有省略……）
Disk /dev/sdb: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 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: 0x44e9daf0
Device Boot Start End Blocks Id System
/dev/sdb1 1 13054 104856223+ 83 Linux
3、LVM管理设置
总的步骤应该是这样：首先需要让LVM认可/dev/sdb1是一个可用的PV（Physical Volume），之后将其加入到VG里面去，补充VG资源。最后拓展lv_root磁盘空间。
当前LVM情况如下：
lvm> vgs
VG #PV #LV #SN Attr VSize VFree
vg_li6 1 3 0 wz--n- 79.51g 0
lvm> lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
lv_home vg_li6 -wi-ao---- 25.63g
lv_root vg_li6 -wi-ao---- 50.00g
lv_swap vg_li6 -wi-ao---- 3.88g
lvm> pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 vg_li6 lvm2 a-- 79.51g 0
此时的pv只有一个/dev/sda2，全部用满。首先创建/dev/sdb1作为PV。
[root@Testserver ~]# pvcreate /dev/sdb1
dev_is_mpath: failed to get device for 8:17
Physical volume "/dev/sdb1" successfully created
[root@Testserver ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 vg_li6 lvm2 a-- 79.51g 0
/dev/sdb1 lvm2 a-- 100.00g 100.00g
往VG里面增加PV，作为空间拓容。
lvm> vgs
VG #PV #LV #SN Attr VSize VFree
vg_li6 1 3 0 wz--n- 79.51g 0
lvm> vgextend vg_li6 /dev/sdb1
Volume group "vg_li6" successfully extended
lvm> vgs
VG #PV #LV #SN Attr VSize VFree
vg_li6 2 3 0 wz--n- 179.50g 100.00g –剩余空间增加
lvm> pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 vg_li6 lvm2 a-- 79.51g 0
/dev/sdb1 vg_li6 lvm2 a-- 100.00g 100.00g
拓展lv_root空间。
[root@Testserver vg_li6]# lvextend -L +70G /dev/vg_li6/lv_root
Extending logical volume lv_root to 120.00 GiB
Logical volume lv_root successfully resized
4、文件系统识别
注意：此时文件系统并没有认可本次增加。
[root@Testserver vg_li6]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_li6-lv_root 50G 20G 27G 43% /
tmpfs 3.9G 232K 3.9G 1% /dev/shm
/dev/sda1 485M 39M 421M 9% /boot
/dev/mapper/vg_li6-lv_home 26G 173M 24G 1% /home
需要使用resize2fs命令进行刷新。
[root@Testserver vg_li6]# resize2fs /dev/vg_li6/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_li6/lv_root is mounted on /; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 8
Performing an on-line resize of /dev/vg_li6/lv_root to 31457280 (4k) blocks.
The filesystem on /dev/vg_li6/lv_root is now 31457280 blocks long.
[root@Testserver vg_li6]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_li6-lv_root 119G 20G 93G 18% /
tmpfs 3.9G 232K 3.9G 1% /dev/shm
/dev/sda1 485M 39M 421M 9% /boot
/dev/mapper/vg_li6-lv_home 26G 173M 24G 1% /home