lvm缩容

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注：缩小LVM分区有风险，缩小之前请备份数据。

扩大lvm可参考之前lvm那章节内容。

[root@fangz ~]# df -lh #显示当前各个分区的使用情况

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Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg-root 992M 181M 760M 20% /
/dev/mapper/vg-usr 2.0G 787M 1.1G 42% /usr
/dev/mapper/vg-var 2.0G 86M 1.8G 5% /var
/dev/sda1 99M 12M 82M 13% /boot
tmpfs 125M 0 125M 0% /dev/shm
/dev/mapper/vg-home 992M 11M 930M 2% /home

缩小前，先卸载/dev/vg/home【扩容不需要卸载】

[root@fangz ~]# umount /dev/vg/home

强制检查/dev/vg/home文件系统的正确性

[root@fangz ~]# e2fsck -f /dev/vg/home

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e2fsck 1.39 (29-May-2006)
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/vg/home: 17/262144 files (17.6% non-contiguous), 44125/1048576 blocks

先缩小/dev/vg/home文件系统的大小

[root@fangz ~]# resize2fs /dev/vg/home 256M

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resize2fs 1.39 (29-May-2006)
Resizing the filesystem on /dev/vg/home to 262144 (1k) blocks.
The filesystem on /dev/vg/home is now 262144 blocks long.

resize2fs 程序可以更改ext2/ext3文件系统。它可以放大和缩小它能够找到的设备上的被umount掉的文件系统。如果文件系统是处于mount状态下，那么它只能做到扩容，前提条件是内核支持在线resize(linux kernel2.6支持在mount状态下扩容但仅限于ext3文件系统)。

再缩小LVM大小

[root@fangz ~]# lvresize -L 256M /dev/vg/home

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WARNING: Reducing active logical volume to 256.00 MB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce home? [y/n]: y
Reducing logical volume home to 256.00 MB
Logical volume home successfully resized

挂载所有分区：

[root@fangz ~]# mount -a

检查各个分区的容量：

[root@fangz ~]# df -lh

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Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg-root 992M 181M 760M 20% /
/dev/mapper/vg-usr 2.0G 787M 1.1G 42% /usr
/dev/mapper/vg-var 2.0G 86M 1.8G 5% /var
/dev/sda1 99M 12M 82M 13% /boot
tmpfs 125M 0 125M 0% /dev/shm
/dev/mapper/vg-home 248M 11M 228M 5% /home