active use of diskgroup "DATA" precludes its dismount

Problem

Environment details:

Restore test environment.

HP-UX myhost1 B.11.31 U ia64

Oracle Database 11g Enterprise Edition Release 11.2.0.2.0

I want to drop database by drop database command.

Because, my SYSTEM tablespace needs recovery and I am lack of archive logs, I haven't chance to issue "drop database".

Further I tried to delete files by RMAN, but it does not work either. Because my controlfile also could not be found. Last resort, I tried flushing ASM disk headers by dd, it does not work either, it still shows DATA diskgroup and ASM disks. And finally I tried to drop disk group...

From asmca and asm command line I get below error message while dropping DATA disk group.

SQL>  DROP DISKGROUP data  INCLUDING CONTENTS;

DROP DISKGROUP data  INCLUDING CONTENTS *

ERROR at line 1:

ORA-15039: diskgroup not dropped ORA-15027: active use of diskgroup "DATA" precludes its dismount

Cause

I do not know the real cause, but, as I stated above, it may be because of following reasons:

- lack of controlfile

-SYSTEM tablespace needs media recovery

Solution

I managed to drop disk group by:

alter diskgroup data dismount force;
drop diskgroup data force including contents;

Note that, below trials does not work, I got same error message, despite the fact that the database remains closed state.

srvctl stop diskgroup -g DATA
srvctl disable diskgroup -g DATA
srvctl stop asm