文档解释
ORA-15072: command requires at least string regular failure groups, discovered only string
Cause: An attempt was made to create either a normal redundancy diskgroup for which fewer than two regular failure groups were both specified and discovered, or a high redundancy diskgroup for which fewer than three regular failure groups were both specified and discovered, or an external redundancy diskgroup for which only quorum disks were both specified and discovered.
Action: Check the that the command does specify the required number of failure groups, and that all of the specified disks are discovered by ASM. A query of the V$ASM_DISK fixed view will show which disks are discovered by ASM. Note that a quorum failure group will not be used as a regular failure group. An external redundancy diskgroup requires at least one regular disk.
ORA-15072 错误是比较常见的在Oracle数据库中的错误，它表明命令需要至少一个正常的失效组，但当前发现的只有一个失效组。
官方解释
当你尝试执行一个访问DISKGROUP_COMMAND结构的命令，比如ALTER DISKGROUP或者DROP DISKGROUP，并且DISKGROUP_COMMAND结构中只包含一个失效组时，就会出现ORA-15072错误。
常见案例
比如你想向一个磁盘组中添加一个磁盘，但是磁盘组中只包含有一个失效的磁盘组时，就会出现ORA-15072错误。另外，如果你想要移除一个磁盘组，但是磁盘组中只有一个失效的磁盘组，也会出现ORA-15072错误。
一般处理方法及步骤
当遇到这个错误时，最好的解决方法就是添加至少一个正常的磁盘组，以便满足命令的执行要求。此外，如果要从磁盘组中移除一个磁盘，那么需要创建一个新的磁盘组，然后将失效磁盘移动到新的磁盘组中，最后再删除原有的磁盘组。
