Database Software

Hi,

we have an ASM version 10.2.0.4.0.
We have 1 diskgroup in it, called DB_DISKGROUP in normal redundancy.
We have 3 disks in it (DISK1,DISK2,DISK3) in 3 failgroup.
I found that DISK1 is OFFLINE, HUNG.
I try to drop it, but I cannot (system altered, but V$ASM_OPERATION is empty, and no change in V$ASM_DISK)
TOTAL_MB-FREE_MB=667576-667538=38 MB on DISK1, and there are 174149 FREE_MB on DISK2 and DISK3. This should be enough for relocation, isn't it?
The LABEL and PATH is empty where the NAME is DISK1 (and where the states ars OFFLINE, HUNG) in V$ASM_DISK.
There is an other row in V$ASM_DISK, where the name is empty, but the LABEL is DISK1 and the PATH is ORCL:DISK1 (what is the proper path of DISK1). The HEADER is MEMBER, but the GROUP_NUMBER is 0, which is not in the V$ASM_DISKGROUP;
The databases are workink properly on this ASM. The ASM was restarted, but the situation is not changed. There was no ORA- error in the alert log in the last year.

-----
My questions are:
Is it hung, because of not enough free space? If not enough free space, into which failgroup should I add a new disk? Into DISK2 and DISK3 to continue the relocation? Or into DISK1 to replace the task of disk DISK1? What size of disk is needed?
What is this strange duplication of the DISK1? What are these strange values in V$ASM_DISK? Is it normal?
How can I solve this situation? How can I drop and add the DISK1?

-----
Some columns of V$ASM (NAME, LABEL, PATH is empty sometimes):

NAME LABEL PATH MOUNT_S HEADER_STATU MODE_ST STATE TOTAL_MB FREE_MB GROUP_NUMBER
null DISK1 ORCL:DISK1 CLOSED MEMBER ONLINE NORMAL 667576 0 0
DISK1 null null MISSING UNKNOWN OFFLINE HUNG 667576 667538 1
DISK2 DISK2 ORCL:DISK2 CACHED MEMBER ONLINE NORMAL 667576 174149 1
DISK3 DISK3 ORCL:DISK3 CACHED MEMBER ONLINE NORMAL 667576 174149 1

-----
I read some forum on internet, but I cannot find a solution. Here are some tryings:

ALTER DISKGROUP DB_DISKGROUP DROP DISK DISK1;
--Diskgroup altered. But no rows in the V$ASM_OPERATION, and no change in the V$ASM_DISKGROUP

ALTER DISKGROUP DB_DISKGROUP ADD DISK 'ORCL:DISK1' NAME DISK1 SIZE 667576M ;
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15010: name is already used by an existing ASM disk

ALTER DISKGROUP DB_DISKGROUP ADD DISK 'ORCL:DISK1' NAME DISK1_2 SIZE 667576M ;
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15033: disk 'ORCL:DISK1' belongs to diskgroup "DB_DISKGROUP"

ALTER DISKGROUP DB_DISKGROUP ONLINE DISKS IN FAILGROUP DISK1;
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15198: operation ONLINE FAILGROUP is not yet available

--Here is my creation script
CREATE DISKGROUP DB_DISKGROUP Normal REDUNDANCY DISK 'ORCL:DISK1' SIZE 667576M ,'ORCL:DISK2' SIZE 667576M ,'ORCL:DISK3' SIZE 667576M

-----
Some (not all) rows from the alert log

--this was the first row related to offlining
NOTE: ASMB process exiting due to lack of ASM file activity
--some other rows from alert log. It seems good for me
WARNING: offlining disk 0.3916207031 (DISK1) with mask 0x3
SUCCESS: refreshed membership for 1/0x39fc6347 (DB_DISKGROUP)
SUCCESS: PST-initiated disk drop completed
SUCCESS: rebalance completed for group 1/0x39fc6347 (DB_DISKGROUP)
--But this is a strange row. What type of reference?
WARNING: offline disk number 0 has references (31 AUs)

Thx: lados