原因分析:
Web管理不能删除特定快照时，可用此方法。
解决方案:
命令：delete snapshot
说明：删除特定快照。删除唯一与快照关联的所有数据后，快照池中的相关空间即可用。同时会删除此快
照的所有计划。
语法：delete snapshot [cleanup] [delete-priority standard-snapshot|volume-copy-snapshot|replication-snapshot|replicating-snapshot|common-sync-point-snapshot|only-sync-point-snapshot|queued-snapshot] [force] snapshots
参数：
cleanup 可选。删除主卷的最后一个快照时，会自动将主卷转换为标准卷，并删除快照池。
delete-priority standard-snapshot|volume-copy-snapshot|replication-snapshot|replicating-snapshot|common-sync-point-snapshot|only-sync-point-snapshot|queued-snapshot 可选。可删除的快照的优先级。如果指定优先级低于快照的优先级，删除操作将被阻止。这么做的目标是为了防止意外删除高优先级的快照。此参数或 force 参数必须指定其一，但不能同时指定。
force 可选。覆盖优先级保护，强制删除指定的快照。此参数或 delete-priority 参数必须指定其一，但不能同时指定。
snapshots 要删除的快照的名称或序列号。
示例：
删除复制操作正在使用的快照 SS1：
# delete snapshot delete-priority replicating-snapshot SS1
Info: Snapshot SS1 was deleted. (SS1)
通过指定较低优先级尝试删除 common-sync-point 快照 SS2：
# delete snapshot delete-priority standard-snapshot SS2
Error: Snapshot priority has not been met.
强制删除快照 SS2：
# delete snapshot force SS2
Info: Snapshot SS2 was deleted. (SS2)
删除三个标准快照：
# delete snapshot s1,s2,s3
Info: Snapshot s1 was deleted. (s1)
Info: Snapshot s2 was deleted. (s2)
Info: Snapshot s3 was deleted. (s3)