事件现象：
最近同事在扩展VG时遇到了“Snapshot origin volumes can be resized only while inactive: try lvchange -an”错误
# partprobe
# mkfs -t ext3 /dev/sdd3
# pvcreate /dev/sdd3
# vgextend VolGroup03 /dev/sdd3
# lvextend -l +40G /dev/mapper/VolGroup03-LogVol00 /dev/sdd3
/dev/VolGroup05/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 279105699840: Input/output error
/dev/VolGroup05/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 279105757184: Input/output error
/dev/VolGroup05/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 0: Input/output error
/dev/VolGroup05/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 4096: Input/output error
/dev/VolGroup01/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 85865725952: Input/output error
/dev/VolGroup01/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 85865783296: Input/output error
/dev/VolGroup01/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 0: Input/output error
/dev/VolGroup01/LogVol00-PS-user-snapshot: read failed after 0 of 4096 at 4096: Input/output error
Snapshot origin volumes can be resized only while inactive: try lvchange -an
出错原因：
被扩展的VG存在LVM快照（LVM snapshot），所以扩展VG时出现上面错误。因为这个LVM快照是PlateSpin使用，上面没有什么数据一定需要保留。所以使用lvremove删除逻辑卷LV，然后扩展VG。 最后创建LV解决。
解决方案
# stat /dev/VolGroup03/LogVol00-PS-user-snapshot
# lvremove /dev/VolGroup03/LogVol00-PS-user-snapshot
# lvextend -L +40G /dev/mapper/VolGroup03-LogVol00 /dev/sdd3
# resize2fs /dev/mapper/VolGroup03-LogVol00
# lvcreate -L 20G -s -n LogVol00-PS-user-snapshot /dev/VolGroup03/LogVol00
如果出于保险起见，那么需要备份LVM快照数据，然后卸载卷组（unmount), 然后就按照上面步骤继续操作