Php文档 Php问答行业资讯 Php论坛 Php手册 Php博客

游戏榜单

软件榜单

关闭导航

热搜榜

热门下载

热门标签

关闭搜索

php爱好者> php文档>lvm2的管理

lvm2的管理

时间：2007-03-21 来源：ghan

苏小勇 http://www.bestunix.net

1.基本概念:

物理卷(pv): 物理卷可以是硬盘,也可以是硬盘上的分区,使用如pvcreate /dev/sdb1来创建一个物理卷.
卷组(vg): 卷组由物理卷组成,可以通过添加,删除物理卷来改变卷组的大小,卷组可以看作传统意义上的可以改变大小的硬盘.
逻辑卷(lv): 逻辑卷对卷组进行的重新划分,相当于传统意义上的可以自由改变大小的硬盘分区.

2.基本操作

创建pv

#pvcreate /dev/sdb2 /dev/sdb3
Physical volume "/dev/sdb2" successfully created
Physical volume "/dev/sdb3" successfully created

创建vg

#vgcreate vg1 /dev/sdb1 /dev/sdb2 /dev/sdb3
Volume group "vg1" successfully created

激活vg

#vgchange -a y vg1
0 logical volume(s) in volume group "vg1" now active

向vg中追加pv

#vgextend vg1 /dev/sdb5
Volume group "vg1" successfully extended

从vg中移走pv(不推荐)

查看pv的使用情况

#pvdisplay /dev/sdb1
  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               vg1
  PV Size               48.00 MB / not usable 0   
  Allocatable           yes 
  PE Size (KByte)       4096
  Total PE              12
  Free PE               12
  Allocated PE          0
  PV UUID               ncdQHn-wRWW-pCJR-2siv-SXSY-vCxq-FBfWrw

查看vg的状态

#vgdisplay vg1
  --- Volume group ---
  VG Name               vg1
  System ID             
  Format                lvm2
  Metadata Areas        4
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                4
  Act PV                4
  VG Size               192.00 MB
  PE Size               4.00 MB
  Total PE              48
  Alloc PE / Size       0 / 0   
  Free  PE / Size       48 / 192.00 MB
  VG UUID               Qzd9qI-5oeA-23b9-FLls-W2Ra-739g-vw36XW

建立LV

# lvcreate -L100M -nlv1 vg1
Logical volume "lv1" created

查看已经建立的LV

lvdisplay 
  --- Logical volume ---
  LV Name                /dev/vg1/lv1
  VG Name                vg1
  LV UUID                ezmFx2-svKD-EVNV-rZxY-HS6P-vnd3-Q9KKOR
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                100.00 MB
  Current LE             25
  Segments               3
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:2

格式化LV

# mkfs.ext3 -b 4096 /dev/vg1/lv1
mke2fs 1.35 (28-Feb-2004)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
25600 inodes, 25600 blocks
1280 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=29360128
block group
32768 blocks per group, 32768 fragments per group
25600 inodes per group
Writing inode tables: done                            
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 21 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

mount LV

# mount /dev/vg1/lv1 /mnt

查看当前系统分区情况,我们可以看到现在lv1的大小是100M

[root@ha1 ~]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       3451040   2644664    631068  81% /
/dev/sda1               101086      9181     86686  10% /boot
none                    127988         0    127988   0% /dev/shm
/dev/mapper/vg1-lv1      99184      4152     89912   5% /mnt

扩展LV的大小

# lvextend -L50M /dev/vg1/lv1
  Rounding up size to full physical extent 52.00 MB
  New size given (13 extents) not larger than existing size (25 extents)
  lvextend: Add space to a logical volume

这个错误是说新的大小比以前的要小,索引不能扩展,我们指定的新的大小必须大于原来的大小.或者用+50M来增加大小.

比如

# lvextend -L120M /dev/vg1/lv1 
  Extending logical volume lv1 to 120.00 MB
  Logical volume lv1 successfully resized

或者

#lvextend -L+20M /dev/vg1/lv1  
  Extending logical volume lv1 to 120.00 MB
  Logical volume lv1 successfully resized

这个时候,我们再看每个分区的大小,还是跟以前一样,并没有增大

# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       3451040   2644668    631064  81% /
/dev/sda1               101086      9181     86686  10% /boot
none                    127988         0    127988   0% /dev/shm
/dev/mapper/vg1-lv1      99184      4152     89912   5% /mnt

在LVM2中,最方便的地方就是,使用ext2online,我们不用卸载原来的LVM就可以改变它的大小.

# ext2online /dev/vg1/lv1
ext2online v1.1.18 - 2001/03/18 for EXT2FS 0.5b

这时候再查看分区的大小,可以看到lv1已经变为120M了.

# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       3451040   2644668    631064  81% /
/dev/sda1               101086      9181     86686  10% /boot
none                    127988         0    127988   0% /dev/shm
/dev/mapper/vg1-lv1     119664      4152    110392   4% /mnt

如果LV所在的VG空间不够的话,在进行lvextend时并不会表现出来,只有在ext2online的时候才会有提示:

ext2online /dev/vg1/lv1
ext2online v1.1.18 - 2001/03/18 for EXT2FS 0.5b
ext2online: ext2_ioctl: No space left on device
ext2online: unable to resize /dev/mapper/vg1-lv1

减小LV

我们说了LV是可以动态调整大小的,既然可以扩展,当然可以减小了.可以使用lvreduce来进行这个操作.

lvreduce -L-50M /dev/vg1/lv1
  Rounding up size to full physical extent 48.00 MB
  WARNING: Reducing active and open logical volume to 92.00 MB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv1? [y/n]: y
  Reducing logical volume lv1 to 92.00 MB
  Logical volume lv1 successfully resized

同样，也需要使用ext2online来使更改生效.

减小lv具有一定的风险,一般情况下不要减小lv