如何减小LVM分区 懂Linux的牛人都来看看

首先，建立新分区物理卷（PV），然后将该分区类型设定为lvm，之后就可以在该PV上建立卷组（VG），然后在VG里划分逻辑卷（LV），每个逻辑卷就相当于一个新的分区。需要调整分区（LV）大小时，如果是扩大LV，需要所属VG还有剩余未分配空间（Free PE），否则据需要先减小其它LV获得可用PE。

再一点，LVM不是自动动态调整大小，而是需要用户调整。

总结就是pvcreate创建pv，然后vgextend增加lvm大小，再lvextend增加lv_root大小，最后resize2fs就成功了[root@localhost 桌面]# pvcreate /dev/sda3

Physical volume "/dev/sda3" successfully created

[root@localhost 桌面]# pvdisplay

--- Physical volume ---

PV Name /dev/sda2

VG Name VolGroup

PV Size 7.80 GB / not usable 1.17 MB

Allocatable yes (but full)

PE Size (KByte) 4096

Total PE 1997

Free PE 0

Allocated PE 1997

PV UUID HtJXq0-Gloi-c6ou-VR3X-5SFz-GyD8-EMdMMZ

"/dev/sda3" is a new physical volume of "1019.75 MB"

--- NEW Physical volume ---

PV Name /dev/sda3

VG Name

PV Size 1019.75 MB

Allocatable NO

PE Size (KByte) 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID jrB6nN-u4aH-2NGy-E7X6-KoOq-aKvn-xhtov0

[root@localhost 桌面]# vgextend VolGroup /dev/sda3

Volume group "VolGroup" successfully extended

[root@localhost 桌面]# vgdisplay

--- Volume group ---

VG Name VolGroup

System ID

Formatlvm2

Metadata Areas2

Metadata Sequence No 5

VG Access read/write

VG Status resizable

MAX LV0

Cur LV2

Open LV 2

Max PV0

Cur PV2

Act PV2

VG Size 8.79 GB

PE Size 4.00 MB

Total PE 2251

Alloc PE / Size 1997 / 7.80 GB

Free PE / Size 254 / 1016.00 MB

VG UUID QXmNgn-tD5Q-Oz2D-g6pf-W9uf-cSIn-3vWImm

[root@localhost 桌面]# lvscan

ACTIVE'/dev/VolGroup/lv_root' [5.83 GB] inherit

ACTIVE'/dev/VolGroup/lv_swap' [1.97 GB] inherit

[root@localhost 桌面]# lvcreate -L 1G -n lv_new VolGroup

Insufficient free extents (254) in volume group VolGroup: 256 required

[root@localhost 桌面]# lvextend -L +1G /VolGroup/lv_root

"/VolGroup/lv_root": Invalid path for Logical Volume

Please provide a volume group name

Run `lvextend --help' for more information.

[root@localhost 桌面]# lvextend -L +1G /dev/VolGroup/lv_root

Extending logical volume lv_root to 6.83 GB

Insufficient free space: 256 extents needed, but only 254 available

[root@localhost 桌面]# lvextend -L +1018m /dev/VolGroup/lv_root

Rounding up size to full physical extent 1020.00 MB

Extending logical volume lv_root to 6.83 GB

Insufficient free space: 255 extents needed, but only 254 available

[root@localhost 桌面]# lvextend -L +1017m /dev/VolGroup/lv_root

Rounding up size to full physical extent 1020.00 MB

Extending logical volume lv_root to 6.83 GB

Insufficient free space: 255 extents needed, but only 254 available

[root@localhost 桌面]# lvextend -L +1016m /dev/VolGroup/lv_root

Extending logical volume lv_root to 6.82 GB

Logical volume lv_root successfully resized

[root@localhost 桌面]# lvscan

ACTIVE'/dev/VolGroup/lv_root' [6.82 GB] inherit

ACTIVE'/dev/VolGroup/lv_swap' [1.97 GB] inherit

[root@localhost 桌面]# pvresize -v /dev/sda2

Using physical volume(s) on command line

Archiving volume group "VolGroup" metadata (seqno 6).

No change to size of physical volume /dev/sda2.

Resizing volume "/dev/sda2" to 16361813 sectors.

Updating physical volume "/dev/sda2"

Creating volume group backup "/etc/lvm/backup/VolGroup" (seqno 7).

Physical volume "/dev/sda2" changed

1 physical volume(s) resized / 0 physical volume(s) not resized[root@localhost /]# resize2fs /dev/VolGroup/lv_root

resize2fs 1.41.9 (22-Aug-2009)

Filesystem at /dev/VolGroup/lv_root is mounted on /on-line resizing required

old desc_blocks = 1, new_desc_blocks = 1

Performing an on-line resize of /dev/VolGroup/lv_root to 1788928 (4k) blocks.

The filesystem on /dev/VolGroup/lv_root is now 1788928 blocks long.

要减小lvm的文件系统 需要文件系统在umount状态下修改 所以在线不要去改重要文件系统

*** 作步骤如下：

1.查看挂载的文件系统和lv

df -h 查看文件系统 ，下面是我要更改的文件系统。这里是99G

/dev/mapper/vg_LogVol01

99G 188M 94G 1% /home

lvdisplay 下面是文件系统对应的逻辑卷（lv）

--- Logical volume ---

LV Name/dev/vg_test/LogVol01

VG Namevg_test

LV UUIDcXylir-3KNW-UQ8a-kXos-fuIy-NAx2-0DJ5Fw

LV Write Accessread/write

LV Status available

# open 1

LV Size100.00 GiB

Current LE 800

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 256

Block device 253:2

2. 卸载文件系统

umount /dev/mapper/vg_LogVol01

3. 查看是否卸载 df -h 文件系统已经没有了

4.文件系统检查 确认没有坏块

e2fsck -f /dev/mapper/vg_LogVol01

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/mapper/vg_LogVol01: 11/6553600 files (0.0% non-contiguous), 459

349/26214400 blocks

5.缩小文件系统 到20g

resize2fs /dev/mapper/vg_LogVol01 20G

resize2fs 1.41.12 (17-May-2010)

Resizing the filesystem on /dev/mapper/vg_LogVol01 to 5242880 (4k) b

locks.

The filesystem on /dev/mapper/vg_LogVol01 is now 5242880 blocks long

6.缩小逻辑卷

lvreduce -L 20G /dev/vg_test/LogVol01

WARNING: Reducing active logical volume to 20.00 GiB

THIS MAY DESTROY YOUR DATA (filesystem etc.)

Do you really want to reduce LogVol01? [y/n]: y

Reducing logical volume LogVol01 to 20.00 GiB

Logical volume LogVol01 successfully resized

7.挂载上文件系统

mount /dev/mapper/vg_LogVol01

8.通过df -h 和lvdisplay来查看是否已经修改

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