Lv的缩减

[@more@]◇查看当前文件系统大小。
# df -h /mnt
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-data
221M 17M 193M 8% /mnt
◇卸载文件系统，因为缩小不支持在线操作。
# umount /mnt
◇将文件系统减小到一个指定的大小，但之前需要检查文件系统的完整性。
# resize2fs /dev/VolGroup00/data +100M
resize2fs 1.39 (29-May-2006)
Please run 'e2fsck -f /dev/VolGroup00/data' first.
◇根据提示做文件系统的完整性检查。
# e2fsck -f /dev/VolGroup00/data
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/VolGroup00/data: 13/30720 files (7.7% non-contiguous), 5194/57344 blocks
◇然后再执行resize2fs命令，这时才真正减小文件系统。
# resize2fs /dev/VolGroup00/data +100M
resize2fs 1.39 (29-May-2006)
Resizing the filesystem on /dev/VolGroup00/data to 25600 (4k) blocks.
The filesystem on /dev/VolGroup00/data is now 25600 blocks long.
◇之后最好查看上一个命令的输出结果，如果为0，则resize2fs命令执行正确。
# echo $?
0
◇重新挂载文件系统，然后检查其大小是否是按照意愿设定的大小。
# mount /dev/VolGroup00/data /mnt
# df -h /mnt
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-data
99M 17M 78M 18% /mnt
◇了解当前PE的大小，因为LV大小=PE大小*PE个数。
# vgdisplay |grep 'PE Size'
PE Size 32.00 MB
◇计算出适当的PE个数，以缩小LV。
# lvresize -l 4 /dev/VolGroup00/data
/dev/cdrom: open failed: Read-only file system
WARNING: Reducing active and open logical volume to 128.00 MB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce data? [y/n]: y
Reducing logical volume data to 128.00 MB
Logical volume data successfully resized
◇检查结果。
# lvs |grep data
data VolGroup00 -wi-ao 128.00M
◇（可选）让文件系统使用全部可用空间。
# resize2fs /dev/VolGroup00/data
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/VolGroup00/data is mounted on /mnt; on-line resizing required
Performing an on-line resize of /dev/VolGroup00/data to 32768 (4k) blocks.
The filesystem on /dev/VolGroup00/data is now 32768 blocks long.