LVM的创建扩容和缩减
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一、创建LVM系统
?1. 硬盘分区
??首先我们需要为我们的虚拟机添加一个虚拟硬盘，过程略。
查看硬盘设备：
[[email protected] ~]# fdisk -l
...
Disk /dev/sdc: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 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: 0xa2c6e480
Device Boot Start End Blocks Id System
...如上/dev/sdc是我们新添加的硬盘设备。
我们需要在/dev/sdc基础上创建分区并修改分区系统类型为8e：
[[email protected] ~]# fdisk /dev/sdc
WARNING: DOS-compatible mode is deprecated. It is strongly recommended to
switch off the mode (command ‘c‘) and change display units to
sectors (command ‘u‘).
Command (m for help): n # 创建新分区
Command action
e extended # 扩展分区
p primary partition (1-4) # 主分区
p
Partition number (1-4): 1 # 分区号
First cylinder (1-1305, default 1): # 默认从第一个柱面开始划分
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1305, default 1305): +5G # 分区大小
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (655-1305, default 655):
Using default value 655
Last cylinder, +cylinders or +size{K,M,G} (655-1305, default 1305): +3G
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (1048-1305, default 1048):
Using default value 1048
Last cylinder, +cylinders or +size{K,M,G} (1048-1305, default 1305):
Using default value 1305
Command (m for help): t # 修改分区系统类型
Partition number (1-4): 1 # 选择要修改的分区号
Hex code (type L to list codes): 8e # 修改为LVM分区类型，可使用‘L‘查看所有可使用类型
Changed system type of partition 1 to 8e (Linux LVM)
Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 8e
Changed system type of partition 2 to 8e (Linux LVM)
Command (m for help): t
Partition number (1-4): 3
Hex code (type L to list codes): 8e
Changed system type of partition 3 to 8e (Linux LVM)
Command (m for help): p # 查看分区情况
Disk /dev/sdc: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 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: 0xa2c6e480
Device Boot Start End Blocks Id System
/dev/sdc1 1 654 5253223+ 8e Linux LVM
/dev/sdc2 655 1047 3156772+ 8e Linux LVM
/dev/sdc3 1048 1305 2072385 8e Linux LVM
Command (m for help): w # 保存分区表并退出
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[[email protected] ~]#
?2. 创建物理卷
创建物理卷的命令为pvcreate，利用该命令将希望添加到卷组的所有分区或者硬盘创建为物理卷。
[[email protected] ~]# pvcreate /dev/sdc{1,2} # 将/dev/sdc1和2创建为物理卷
Physical volume "/dev/sdc1" successfully created
Physical volume "/dev/sdc2" successfully created
[[email protected] ~]# pvs # 查看物理卷信息
PV VG Fmt Attr PSize PFree
/dev/sdc1 lvm2 ---- 5.01g 5.01g
/dev/sdc2 lvm2 ---- 3.01g 3.01g
[[email protected] ~]# pvdisplay # 查看物理卷详细信息
...
"/dev/sdc1" is a new physical volume of "5.01 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc1
VG Name
PV Size 5.01 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID jKHeSG-XYna-zFYi-9Kd9-bWRM-f1zY-Qs7FZZ
"/dev/sdc2" is a new physical volume of "3.01 GiB"
--- NEW Physical volume ---
PV Name /dev/sdc2
VG Name
PV Size 3.01 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID WcKTKi-av0e-so5s-QVXB-yf7G-Tynz-9TQDJb
[[email protected] ~]#
?3. 创建卷组
创建卷组的命令为vgcreate，将使用pvcreate建立的物理卷创建为一个完整的卷组。
[[email protected] ~]# vgcreate myvg /dev/sdc{1,2} # 创建卷组
Volume group "myvg" successfully created
[[email protected] ~]# vgs # 查看卷组信息
VG #PV #LV #SN Attr VSize VFree
myvg 2 0 0 wz--n- 8.02g 8.02g
[[email protected] ~]# vgdisplay myvg # 查看卷组详细信息
--- Volume group ---
VG Name myvg
System ID
Format lvm2
Metadata Areas 2
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 2
Act PV 2
VG Size 8.02 GiB # 卷组的大小，由上面两个分区决定
PE Size 4.00 MiB # PE大小可以在vgcreate命令中使用‘-s‘指定，默认为4M
Total PE 2052
Alloc PE / Size 0 / 0
Free PE / Size 2052 / 8.02 GiB
VG UUID 4aIItM-FyPx-GJ47-1A70-b8W4-EwfH-beFZrZ
[[email protected] ~]# pvdisplay # 再次查看物理卷，跟上一次查看有所区别
--- Physical volume ---
PV Name /dev/sdc1
VG Name myvg
PV Size 5.01 GiB / not usable 2.10 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 1282
Free PE 1282
Allocated PE 0
PV UUID jKHeSG-XYna-zFYi-9Kd9-bWRM-f1zY-Qs7FZZ
--- Physical volume ---
PV Name /dev/sdc2
VG Name myvg
PV Size 3.01 GiB / not usable 2.79 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 770
Free PE 770
Allocated PE 0
PV UUID WcKTKi-av0e-so5s-QVXB-yf7G-Tynz-9TQDJb
[[email protected] ~]#
?4. 创建逻辑卷
创建逻辑卷的命令为lvcreate
[[email protected] ~]# lvcreate -L 6G -n mylv myvg
Logical volume "mylv" created.
[[email protected] ~]#使用方法：
lvcreate -L #G -n LV_NAME VG_NAME
参数解释：
-L: 指定逻辑卷大小，不可超过卷组大小
-n: 指定逻辑卷名称
?5. 挂载文件系统
至此我们的逻辑卷就已创建完成，接下来我们就需要格式化分区并挂载使用啦。
[[email protected] ~]# mkfs.ext4 /dev/myvg/mylv # 格式化分区
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
393216 inodes, 1572864 blocks
78643 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1610612736
48 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
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 36 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[[email protected] ~]# mount /dev/myvg/mylv /mnt/ # 挂载分区到/mnt目录下
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/myvg-mylv
5.8G 12M 5.5G 1% /mnt
[[email protected] ~]#
二、扩展逻辑卷
上一章我们介绍了如何创建LVM系统，并挂载使用。如果我们分配的空间不够用，那么就需要我们来扩展分区大小了。
接下来我们将/dev/sdc3分区也加入到卷组，并扩展逻辑卷空间。
[[email protected] ~]# pvcreate /dev/sdc3 # 创建物理卷
Physical volume "/dev/sdc3" successfully created
[[email protected] ~]# vgextend myvg /dev/sdc3 # 添加物理卷到卷组
Volume group "myvg" successfully extended
[[email protected] ~]# pvs # 查看物理卷信息
PV VG Fmt Attr PSize PFree
/dev/sdb datavg lvm2 a--u 20.00g 1020.00m
/dev/sdc1 myvg lvm2 a--u 5.01g 0
/dev/sdc2 myvg lvm2 a--u 3.01g 2.02g
/dev/sdc3 myvg lvm2 a--u 1.97g 1.97g # /dev/sdc3已加入myvg卷组
[[email protected] ~]# vgs # 卷组信息
VG #PV #LV #SN Attr VSize VFree
datavg 1 1 0 wz--n- 20.00g 1020.00m
myvg 3 1 0 wz--n- 9.99g 3.99g # 卷组容量比之前扩大
[[email protected] ~]# lvextend -L 9G /dev/myvg/mylv # 扩展逻辑卷容量到9G
Size of logical volume myvg/mylv changed from 6.00 GiB (1536 extents) to 9.00 GiB (2304 extents).
Logical volume mylv successfully resized.
[[email protected] ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
nsas01 datavg -wi-ao---- 19.00g
mylv myvg -wi-a----- 9.00g # 逻辑卷容量成功扩展到9G
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/myvg-mylv
5.8G 12M 5.5G 1% /mnt # 但是分区空间还是初始大小
[[email protected] ~]# resize2fs -p /dev/myvg/mylv # 改变分区大小为逻辑卷大小
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/myvg/mylv is mounted on /mnt; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/myvg/mylv to 2359296 (4k) blocks.
The filesystem on /dev/myvg/mylv is now 2359296 blocks long.
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/myvg-mylv
8.8G 14M 8.3G 1% /mnt # 分区大小成功扩展到9G
[[email protected] ~]#
三、缩减逻辑卷
注意事项：
- 缩减前需要先卸载挂载；
- 要确保缩减后的空间依然能够存储原有的所有数据；
- 缩减之前需要先强行检查文件，确保文件系统处于一致性状态。
[[email protected] ~]# umount /dev/myvg/mylv # 卸载挂载分区
[[email protected] ~]# e2fsck -f /dev/myvg/mylv # 强行检查文件系统
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/myvg/mylv: 11/589824 files (0.0% non-contiguous), 73247/2359296 blocks
[[email protected] ~]# resize2fs /dev/myvg/mylv 8G # 改变分区大小
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/myvg/mylv to 2097152 (4k) blocks.
The filesystem on /dev/myvg/mylv is now 2097152 blocks long.
[[email protected] ~]# lvreduce -L 8G /dev/myvg/mylv # 改变逻辑卷大小
WARNING: Reducing active logical volume to 8.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce myvg/mylv? [y/n]: y
Size of logical volume myvg/mylv changed from 9.00 GiB (2304 extents) to 8.00 GiB (2048 extents).
Logical volume mylv successfully resized.
[[email protected] ~]# mount /dev/myvg/mylv /mnt/
[[email protected] ~]# df -h
...
/dev/mapper/myvg-mylv
7.8G 14M 7.4G 1% /mnt # 分区大小成功缩减为8G
[[email protected] ~]#
四、从卷组移除物理卷
[[email protected] ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
nsas01 datavg -wi-ao---- 19.00g
mylv myvg -wi-ao---- 8.00g
[[email protected] ~]# vgs
VG #PV #LV #SN Attr VSize VFree
datavg 1 1 0 wz--n- 20.00g 1020.00m
myvg 3 1 0 wz--n- 9.99g 1.99g
[[email protected] ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdc1 myvg lvm2 a--u 5.01g 0
/dev/sdc2 myvg lvm2 a--u 3.01g 16.00m
/dev/sdc3 myvg lvm2 a--u 1.97g 1.97g
[[email protected] ~]#
我们的目前状态：
挂载分区空间为8G；
逻辑卷(LV)空间大小为8G；
卷组(VG)空间大小为9.99G，剩余1.99G；
物理卷/dev/sdc3空间未使用。
那么我们是否可以将/dev/sdc3从卷组中移除出来呢？
[[email protected] ~]# pvmove /dev/sdc3 # 移动/dev/sdc3中数据到其他物理卷
No data to move for myvg
[[email protected] ~]# vgreduce myvg /dev/sdc3 # 从myvg卷组中移除/dev/sdc3物理卷
Removed "/dev/sdc3" from volume group "myvg"
[[email protected] ~]# pvremove /dev/sdc3 # 移除物理卷/dev/sdc3
Labels on physical volume "/dev/sdc3" successfully wiped
[[email protected] ~]# pvs # /dev/sdc3成功从卷组myvg中移除
PV VG Fmt Attr PSize PFree
/dev/sdb datavg lvm2 a--u 20.00g 1020.00m
/dev/sdc1 myvg lvm2 a--u 5.01g 0
/dev/sdc2 myvg lvm2 a--u 3.01g 16.00m
[[email protected] ~]# vgs # 卷组空间大小缩减了/dev/sdc3空间大小
VG #PV #LV #SN Attr VSize VFree
datavg 1 1 0 wz--n- 20.00g 1020.00m
myvg 2 1 0 wz--n- 8.02g 16.00m
[[email protected] ~]#
五、常用命令
- 物理卷管理(PV)
pvcreate、pvdisplay、pvmove、pvremove、pvs- 卷组管理(VG)
vgcreate、vgdisplay、vgextend、vgreduce、vgremove、vgrename、vgs- 逻辑卷管理(LV)
lvcreate、lvdisplay、lvextend、lvreduce、lvremove、lvrename、lvs
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