lvm study

lvm study:

lvm名词：PV, PE, VG, LV

 

操做流程：

一、更改分区模式：

#fdisk /dev/sda

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Command (m for help): t

Partition number (1-5): 5

Hex code (type L to list codes): 8e

Changed system type of partition 5 to 8e (Linux LVM)

 

Command (m for help): p

 

Disk /dev/sda: 320.0 GB, 320072933376 bytes

255 heads, 63 sectors/track, 38913 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

 

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1          33      265041   83  Linux

/dev/sda2              34        2644    20972857+  83  Linux

/dev/sda3            2645        3166     4192965   82  Linux swap / Solaris

/dev/sda4            3167       38913   287137777+   5  Extended

/dev/sda5            3167       38913   287137746   8e  Linux LVM

 

Command (m for help): w

The partition table has been altered!

 

Calling ioctl() to re-read partition table.

 

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table.

The new table will be used at the next reboot.

Syncing disks.

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#partprobe

 

#PV操做阶段

 

#pvcreate /dev/sda5

Physical volume "/dev/sda5" successfully created  表示执行成功。

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此处报错：Can't open /dev/sda5 exclusively. Mounted filesystem?

解决以下：

#df -h 查找dev/sda5挂载的分区，卸载掉。

#umount /dev/sda5

执行完检查没有挂载后，从新执行上面的命令。

===================================================================

#pvscan

#pvdisplay

 

 

VG操做阶段

 

#vgcreate -s 16M vgdisk /dev/sda5  建立一个名位vgdisk的VG，且制定pe为16M

#vgscan

#vgdisplay

 

 

增长VG的容量命令：

  vgextend vgdisk /dev/sda6   (这里是假设还有个sda6的pv)

 

=====================================================================

 

LV阶段：

 

#lvcreate -l 7000 -n lvdisk vgdisk  建立一个7000个PE的名称为lvdisk的LV

# ll /dev/vgdisk/lvdisk 

lrwxrwxrwx 1 root root 29 Dec  7 11:01 /dev/vgdisk/lvdisk -> /dev/mapper/vgdisk-lvdisk

#lvdisplay

 

  Block device           253:0

 

#档案系统阶段：

#mkfs.ext3 /dev/vgdisk/lvdisk

#mount /dev/vgdisk/lvdisk /data

 

这样LV就挂载上了，咱们能够作任何操做了。。

 

=========================================================================

下面是一些平常的维护操做：

一、放大LV容量

#lvextend -L +50G /dev/mapper/vgdisk-lvdisk

#resize2fs /dev/mapper/vgdisk-lvdisk

#df -h       显示成功加到117.58G

 

二、缩小LV容量

#umount /data

#e2fsck -f /dev/mapper/vgdisk-lvdisk

#resize2fs /dev/mapper/vgdisk-lvdisk 20G     #后面的20G表示缩小后的值。

#lvresize -L 20G /dev/mapper/vgdisk-lvdisk

#mount /dev/mapper/vgdisk-lvdisk /data

#df -h  #检查是否到达所要缩小到的大小

 

三、删除lv卷：lvremove /dev/mapper/vgdisk-lvdisk

   删除vg组：vgremove /dev/vgdisk

 删除物理卷：pvremove /dev/sda5

 

四、建立磁盘快照：

#lvcreate -L 50G -s lvdiskbackup /dev/vgdisk/lvdisk     #建立快照

#mkdir /mnt/lvdiskbackup

#mount /dev/vgdisk/lvdisk /mnt/lvdiskbackup

#umount /mnt/lvdiskbackup

#lvremove /dev/vgdisk/lvdiskbackup             #删除快照

最后检查数据彻底一致，确认正常。