LVM 管理之二：缩减 LV 大小

转载http://francs3.blog.163.com/blog/static/4057672720122299250175/

今天学习了 RHEL6 缩减 LV 大小，下面的例子目标是将LV "/dev/mapper/vg_redhat6-lv_pgdata_01"
缩小 86 M。    
 

--1 当前LVM 信息

/dev/mapper/vg_redhat6-lv_root                        13G  7.7G  4.6G  63% / tmpfs                 250M  264K  250M   1% /dev/shm /dev/sda1             485M   31M  429M   7% /boot /dev/sr0              2.9G  2.9G     0 100% /media/RHEL_6.2 i386 Disc 1 /dev/mapper/vg_redhat6-lv_pgdata_01                       786M  593M  154M  80% /database/skytf/pgdata1

   
                     

--2 卸载文件系统 ( unmount )

[root@redhat6 ~]# umount /dev/mapper/vg_redhat6-lv_pgdata_01

--3 检查文件系统( e2fsck )

[root@redhat6 ~]# e2fsck /dev/mapper/vg_redhat6-lv_pgdata_01 e2fsck 1.41.12 (17-May-2010) /dev/mapper/vg_redhat6-lv_pgdata_01: clean, 236/49152 files, 154817/179200 blocks

   

   
--4 缩小文件系统 ( resize2fs )

[root@redhat6 ~]# resize2fs -f /dev/mapper/vg_redhat6-lv_pgdata_01 700M resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/mapper/vg_redhat6-lv_pgdata_01 to 179200 (4k) blocks. The filesystem on /dev/mapper/vg_redhat6-lv_pgdata_01 is now 179200 blocks long.

                
 
--5 缩小LV大小（ lvreduce ）

[root@redhat6 ~]# lvreduce -L 700M /dev/mapper/vg_redhat6-lv_pgdata_01   WARNING: Reducing active logical volume to 700.00 MiB   THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce lv_pgdata_01? [y/n]: y   Reducing logical volume lv_pgdata_01 to 700.00 MiB   Logical volume lv_pgdata_01 successfully resized

     
 
--6 查看当前 LV 大小

[root@redhat6 ~]# lvs   LV           VG         Attr   LSize   Origin Snap%  Move Log Copy%  Convert   lv_pgdata_01 vg_redhat6 -wi-a- 700.00m                                        lv_root      vg_redhat6 -wi-ao  13.10g                                        lv_swap      vg_redhat6 -wi-ao   1.91g

  
 备注： 逻辑卷  lv_pgdata_01 已经缩减成 700M了。
 

--7 重新挂载文件系统，查看 

[root@redhat6 ~]# mount  -t ext4 /dev/mapper/vg_redhat6-lv_pgdata_01 /database/skytf/pgdata1 [root@redhat6 ~]# df -h Filesystem            Size  Used Avail Use% Mounted on /dev/mapper/vg_redhat6-lv_root                        13G  7.7G  4.6G  63% / tmpfs                 250M  264K  250M   1% /dev/shm /dev/sda1             485M   31M  429M   7% /boot /dev/sr0              2.9G  2.9G     0 100% /media/RHEL_6.2 i386 Disc 1 /dev/mapper/vg_redhat6-lv_pgdata_01                       688M  593M   61M  91% /database/skytf/pgdata1

       
                    
       备注：目录 /database/skytf/pgdata1  已成功缩减到 700M 左右。         
       --8 总结
 
    在缩减LV 大小前，首先得先缩减文件系统大小。