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

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/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 )

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[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 )

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[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 )

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[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

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[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

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[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。

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