LVM 管理之二：缩减 LV 大小

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

3 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.

4 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

5 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。

6 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。

7 总结

在缩减LV 大小前，首先得先缩减文件系统大小。

原创文章，作者：kirin，如若转载，请注明出处：https://blog.ytso.com/237839.html

LVM 管理之二：缩减 LV 大小

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