服务器评测
LVM是 Logical Volume Manager(逻辑卷管理)的简写，它是Linux环境下对磁盘分区进行管理的一种机制，它由Heinz Mauelshagen在Linux 2.4内核上实现，目前最新版本为：稳定版1.0.5，开发版 1.1.0-rc2，以及LVM2开发版。
LVM是建立在硬盘和分区之上的一个逻辑层，来提高磁盘分区管理的灵活性
可以看一下lvm的示意图
每个磁盘可以分成多个分区，每个分区相当于一个pv，将pv化分成vg，在vg的基础上创建逻辑分区lv，逻辑分区lv上创建操作系统的文件系统。注意boot需要直接建到物理分区上去的。
RedHat默认情况下是安装lvm包的。
检测操作系统是否安装了lvm
[root@rac3 ~]# rpm -qa |grep lvm
system-config-lvm-1.1.4-1.3.el4
lvm2-2.02.42-5.el4
在支持热插拔的服务器上安装一块硬盘。
先用partprobe扫描是否有新的磁盘在用fdisk -l查看磁盘，我安装的磁盘就是最后一个
Disk /dev/sdg: 1073 MB, 1073741824 bytes
[root@rac3 ~]# partprobe
[root@rac3 ~]# fdisk -l
Disk /dev/sda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 140 1020127+ 8e Linux LVM
/dev/sda3 141 1305 9357862+ 8e Linux LVM
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 37 297171 83 Linux
/dev/sdb2 38 74 297202+ 83 Linux
/dev/sdb3 75 561 3911827+ 83 Linux
/dev/sdb4 562 1305 5976180 83 Linux
Disk /dev/sdc: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 1 130 1044193+ 83 Linux
Disk /dev/sdd: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdd1 1 130 1044193+ 83 Linux
Disk /dev/sde: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sde1 1 522 4192933+ 83 Linux
Disk /dev/sdf: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdf1 1 522 4192933+ 8e Linux LVM
Disk /dev/sdg: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdg doesn’t contain a valid partition table
1、先对磁盘进行分区格式化
[root@rac3 ~]# fdisk /dev/sdg
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. 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)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-130, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-130, default 130):
Using default value 130
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
2、创建pv，
如果想将整个磁盘创建成一个物理卷，用下面，
[root@rac3 ~]# pvcreate /dev/sdg
Physical volume “/dev/sdg” successfully created
也可以将当个分区创建成一个物理卷
[root@rac3 ~]# pvcreate /dev/sdg1
Physical volume “/dev/sdg1” successfully created
查看所有的pv
[root@rac3 ~]# pvscan
PV /dev/sda2 VG VolGroup00 lvm2 [992.00 MB / 0 free]
PV /dev/sda3 VG VolGroup00 lvm2 [8.91 GB / 0 free]
PV /dev/sdf1 VG VolGroup00 lvm2 [3.97 GB / 0 free]
PV /dev/sdg lvm2 [1.00 GB]
PV /dev/sdg1 lvm2 [1019.72 MB]
Total: 5 [15.84 GB] / in use: 3 [13.84 GB] / in no VG: 2 [2.00 GB]
查看物理卷组
[root@rac3 ~]# vgscan
Reading all physical volumes. This may take a while…
Found volume group “VolGroup00” using metadata type lvm2
可以看到目前只有一个物理卷组
可以将新添加的物理卷添加到这个物理卷组中
[root@rac3 ~]# vgextend VolGroup00 /dev/sdg1
Volume group “VolGroup00” successfully extended
查看已经有的lv
[root@rac3 ~]# lvscan
ACTIVE ‘/dev/VolGroup00/LogVol01’ [12.88 GB] inherit
ACTIVE ‘/dev/VolGroup00/LogVol00’ [992.00 MB] inherit
可以看到刚才扩展的VolGroup00上创建了两个lv
扩展系统文件占用的那个lv /dev/VolGroup00/LogVol01
在扩展的时候先看看vg空闲空间
— Volume group —
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 4
Metadata Sequence No 8
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 4
Act PV 4
VG Size 14.81 GB
PE Size 32.00 MB
Total PE 474
Alloc PE / Size 474 / 14.81 GB
Free PE / Size 0 / 0 –这里显示vg的空余空间
VG UUID RC2l2s-SAFG-IeDh-qKiT-wDwf-bDfj-DGBoKo
扩展lv
[root@rac3 ~]# lvresize -L +0.96G /dev/VolGroup00/LogVol01
Rounding up size to full physical extent 992.00 MB
Extending logical volume LogVol01 to 13.84 GB
Logical volume LogVol01 successfully resized
这时候需要在线重建lv
[root@rac3 ~]# ext2online /dev/mapper/VolGroup00-LogVol01
查看文件系统已经添加上去了，/dev/mapper/VolGroup00-LogVol01多了1G的空间
[root@rac3 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol01
14G 7.9G 5.2G 61% /
/dev/sda1 99M 14M 81M 14% /boot
none 196M 0 196M 0% /dev/shm
/dev/sdc1 1020M 145M 875M 15% /ocr
/dev/sdd1 1020M 147M 873M 15% /votingdisk
