在Linux平台如何创建一个卷组（VG）呢？下面简单介绍一下卷组（VG）的创建步骤。本文实验平台为Red Hat Enterprise Linux Server release 6.6 (Santiago)
1： 查看当前卷组信息
查看服务器的卷组（VG）、物理卷（PV）、逻辑卷（LV）相关信息，在此之前，我们先来看看一些基本命令以及用法
vgcan命令介绍 :
查找系统中存在的LVM卷组，并显示找到的卷组列表。vgscan命令仅显示找到的卷组的名称和LVM元数据类型，要得到卷组的详细信息需要使用vgdisplay命令。
vgscan的参数：
| [—cache] | Scan devices for LVM physical volumes and volume groups and instruct the lvmetad daemon to update its cached state accordingly |
| [--commandprofile ProfileName] | |
| [-d|--debug] | 调试模式 |
| [-h|--help] | 查看帮助信息 |
| [--ignorelockingfailure] | 忽略锁定失败的错误。 |
| [--mknodes] | Also checks the LVM special files in /dev that are needed for active logical volumes and creates any missing ones and removes unused ones |
| [-P|--partial] | 部分模式。将处理不完整的逻辑卷 |
| [-v|--verbose] | 显示输出详细信息 |
| [--version] | 查看命名版本信息 |
pvscan命令介绍：
扫描系统中连接的所有硬盘，列出找到的物理卷列表。
pvscan的参数:
pvscan
| [-b|—background] | 在后台运行这个命令 |
| [--cache [-a|--activate ay] [ DevicePath | --major major --minor minor]...] | |
| [--commandprofile ProfileName] | |
| [-d|—debug] | 调试模式 |
| {-e|--exported | -n|—novolumegroup} | -e 仅显示属于输出卷组的物理卷; -n 仅显示不属于任何卷组的物理卷; |
| [-h|-?|--help] | 显示命令的帮助信息 |
| [—ignorelockingfailure] | 忽略锁定失败的错误。 |
| [-P|—partial] | 部分模式. 将处理不完整的逻辑卷 |
| [--readonly] | |
| [-s|—short] | 简短格式输出 |
| [-u|—uuid] | 显示输出UUID信息 |
| [-v|—verbose] | 显示输出详细信息 |
| [—version] | 查看pvscan命令版本 |
lvscan命令介绍 ：
扫描当前系统中存在的所有LVM的逻辑卷（lv)
lvscan的参数：
| [-a|—all] | 输出所有的逻辑卷信息 |
| [-b|--blockdevice] | 显示逻辑卷的主设备号和次设备号 |
| [--cache] | |
| [--commandprofile ProfileName] | |
| [-d|—debug] | 调试模式 |
| [-h|-?|--help] | 查看命令的帮助信息 |
| [——ignorelockingfailure] | 忽略锁定失败的错误。 |
| [-P|—partial] | 部分模式. 将处理不完整的逻辑卷 |
| [--readonly] | |
| [-v|—verbose] | 输出详细的结果 |
| [—version] | 查看lvscan命令版本 |
[root@getlnx20 ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VolGroup00" using metadata type lvm2
[root@getlnx20 ~]# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [39.51 GiB / 0 free]
Total: 1 [39.51 GiB] / in use: 1 [39.51 GiB] / in no VG: 0 [0 ]
[root@getlnx20 ~]# lvscan
ACTIVE '/dev/VolGroup00/lv_root' [31.51 GiB] inherit
ACTIVE '/dev/VolGroup00/lv_swap' [8.00 GiB] inherit
[root@getlnx20 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-lv_root
31G 2.5G 27G 9% /
tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/sda1 477M 33M 419M 8% /boot
[root@getlnx20 ~]#
新增一块硬盘后，使用fdisk -l命令，我们可以看到这块新增的硬盘被标记为/dev/sdb
[root@getlnx20 ~]# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
64 heads, 32 sectors/track, 40960 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0006822c
Device Boot Start End Blocks Id System
/dev/sda1 * 2 501 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 502 40960 41430016 8e Linux LVM
Partition 2 does not end on cylinder boundary.
Disk /dev/mapper/VolGroup00-lv_root: 33.8 GB, 33831256064 bytes
255 heads, 63 sectors/track, 4113 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/VolGroup00-lv_swap: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 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/sdb: 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: 0x00000000
新增一个80G的硬盘，但是为什么使用fdisk -l命令查看到的是85.9G？相信很多人看到这个都会有些疑惑。这个是因为计算时使用的单位有所差异所致， 85899345920/1024/1024/1024=80G，而85899345920/1000/1000/1000 ~= 85.899 ~= 85.9G 。
2： 新建一个分区（partition）
新建一个主分区（primary partition）或逻辑分区（logical partition）都OK
[root@getlnx20 ~]# 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 0xaa12f277.
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
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-10443, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-10443, default 10443): Using default value 10443
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
3：创建PV（物理卷）
[root@getlnx20 ~]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created
[root@getlnx20 ~]# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [39.51 GiB / 0 free]
PV /dev/sdb1 lvm2 [80.00 GiB]
Total: 2 [119.51 GiB] / in use: 1 [39.51 GiB] / in no VG: 1 [80.00 GiB]
4：创建VG（卷组）
[root@getlnx20 ~]# vgcreate -s 32M VolGroup01 /dev/sdb1
Volume group "VolGroup01" successfully created
[root@getlnx20 ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "VolGroup01" using metadata type lvm2
Found volume group "VolGroup00" using metadata type lvm2
5：查看VG可用空间
[root@getlnx20 ~]# vgdisplay
--- Volume group ---
VG Name VolGroup01
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 79.97 GiB
PE Size 32.00 MiB
Total PE 2559
Alloc PE / Size 0 / 0
Free PE / Size 2559 / 79.97 GiB
VG UUID FD5kEp-a9Cv-K181-Xb7e-i8k4-zV52-Dbuxc3
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 39.51 GiB
PE Size 4.00 MiB
Total PE 10114
Alloc PE / Size 10114 / 39.51 GiB
Free PE / Size 0 / 0
VG UUID sWwXef-0AHf-66ZI-dZHh-JuJt-KMj7-YqIisW
[root@getlnx20 ~]#
6：建立逻辑卷（LV）
[root@getlnx20 ~]# lvcreate -L79.97G -n LogVol00 VolGroup01
Rounding up size to full physical extent 80.00 GiB
Volume group "VolGroup01" has insufficient free space (2559 extents): 2560 required.
[root@getlnx20 ~]# lvcreate -L79.96G -n LogVol00 VolGroup01
Rounding up size to full physical extent 79.97 GiB
Logical volume "LogVol00" created
[root@getlnx20 ~]# lvscan
ACTIVE '/dev/VolGroup01/LogVol00' [79.97 GiB] inherit
ACTIVE '/dev/VolGroup00/lv_root' [31.51 GiB] inherit
ACTIVE '/dev/VolGroup00/lv_swap' [8.00 GiB] inherit
7：建立文件系统
[root@getlnx20 ~]# mkfs -t ext3 /dev/VolGroup01/LogVol00
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
5242880 inodes, 20963328 blocks
1048166 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
640 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 24 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
8：建立挂载点
[root@getlnx20 ~]# mkdir /mysqldata
9：挂载存储
[root@getlnx20 ~]# mount /dev/VolGroup01/LogVol00 /mysqldata
[root@getlnx20 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-lv_root
31G 2.5G 27G 9% /
tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/sda1 477M 33M 419M 8% /boot
/dev/mapper/VolGroup01-LogVol00
79G 184M 75G 1% /mysqldata
[root@getlnx20 ~]#
10：修改fstab配置文件实现自动挂载
[root@getlnx20 ~]# more /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Jun 13 10:29:07 2015
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/VolGroup00-lv_root / ext4 defaults 1 1
UUID=5486634e-ec6a-42d5-bbb9-dcd92537c294 /boot ext4 defaults 1 2
/dev/mapper/VolGroup00-lv_swap swap swap defaults 0 0
/dev/VolGroup01/LogVol00 /mysqldata ext3 defaults 1 1
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
[root@getlnx20 ~]#
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