Linux LVM学习总结——创建卷组VG-白红宇

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 ~]#