逻辑卷挂载在/mnt下，快照挂载在/media下
创建大小为100M快照
# lvcreate -s -p r -L 100M -n lvtest_snap /dev/myvg/lvtest
Rounding up size to full physical extent 112.00 MB
Logical volume "lvtest_snap" created
# mount /dev/myvg/lvtest_snap /media/
mount: block device /dev/myvg/lvtest_snap is write-protected, mounting read-only
创建大小为10M的文件
# dd if=/dev/zero of=/mnt/bigfile bs=1M count=10
创建前
# lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
lvtest myvg owi-ao 3.00G
lvtest_snap myvg sri-ao 112.00M lvtest 0.03
创建后，快照有所增长
# lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
lvtest myvg owi-ao 3.00G
lvtest_snap myvg sri-ao 112.00M lvtest 9.07
继续创建大文件
# dd if=/dev/zero of=/mnt/bigfile2 bs=1M count=10
# dd if=/dev/zero of=/mnt/bigfile2 bs=1M count=100
快照损坏
# lvs
/dev/myvg/lvtest_snap: read failed after 0 of 4096 at 3221159936: Input/output error
/dev/myvg/lvtest_snap: read failed after 0 of 4096 at 3221217280: Input/output error
/dev/myvg/lvtest_snap: read failed after 0 of 4096 at 0: Input/output error
/dev/myvg/lvtest_snap: read failed after 0 of 4096 at 4096: Input/output error
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
lvtest myvg owi-ao 3.00G
lvtest_snap myvg Sri-I- 112.00M lvtest 100.00
df -h看到刚才挂载到/media下的快照，没有了，并且无法挂载
