ORA-15001: diskgroup “string” does not exist or is not mounted
Cause: An operation failed because the diskgroup specified does not exist or is not mounted by the current ASM instance.
Action: Verify that the diskgroup name used is valid, that the diskgroup exists, and that the diskgroup is mounted by the current ASM instance.
ORA-15001: diskgroup “string” does not exist or is not mounted 是Oracle数据库中常见的错误，该错误表明指定的盘组不存在或未挂载。
ORA-15001: diskgroup “string” does not exist or is not mounted
Cause: An operation was attempted on a diskgroup that does not exist or is not mounted.
Action: Ensure that the specified diskgroup exists, then retry the operation.
1）当进行alter diskgroup操作时，此报错也可能发生。
2）使用create diskgroup操作创建在已经存在的磁盘上时，这个错误也可能发生。
3）在使用drop diskgroup操作删除磁盘组时，这个错误也可能发生。
1）确保指定的磁盘组实际存在，并且已经挂载，也就是磁盘组状态为mounted。
2）要查看磁盘组信息，可以使用SQL语句：
select name,state from v$asm_diskgroup;
3）确保相应的文件系统正确，比如对于非ASM盘组，要确保块大小一致，此外，磁盘的扩展属性也需正确无误，最后确保磁盘上的读写权限正确。
4）如果上述步骤检查无误，则可以尝试重新挂载磁盘组。首先，使用drop diskgroup语句移除磁盘组，紧接着，使用create diskgroup或add diskgroup语句重新添加磁盘组。
5）重新添加磁盘组后，可以运行检查磁盘组状态的SQL语句确定磁盘组是否挂载成功。