Server Administration :: ASM Rebalance Operation Never End

I had added a new disk into disk group DATA1 with rebalance power of 5, it ran as estimated for about 2 days long, I can see the estimated time down to zero but the process never end.

The command used:

SQL> alter diskgroup DATA1 add disk '<path>' rebalance power 5;

Below is the disk status:

SQL> select group_number, disk_number, total_mb, free_mb, mount_status, header_status, state
from v$asm_disk where group_number=1 order by disk_number;

GROUP_NUMBER DISK_NUMBER TOTAL_MB FREE_MB MOUNT_S HEADER_STATU STATE
------------ ----------- ---------- ---------- ------- ------------ --------
1 0 1191626 314236 CACHED MEMBER NORMAL
1 1 1191626 314230 CACHED MEMBER NORMAL
1 2 1191626 314232 CACHED MEMBER NORMAL
1 3 1191602 314229 CACHED MEMBER NORMAL
1 4 1191626 314210 CACHED MEMBER NORMAL
1 5 1191626 314218 CACHED MEMBER NORMAL
1 6 1191626 314218 CACHED MEMBER NORMAL
1 7 1191602 314223 CACHED MEMBER NORMAL
1 8 1191626 314216 CACHED MEMBER NORMAL
1 9 1191626 314202 CACHED MEMBER NORMAL
1 10 1191626 314230 CACHED MEMBER NORMAL
[code]....

I've checked and follow the status for a few days more, it still running with EST_MINUTES=0. I think it was hang and never end.During the next few weeks, I've manually restarted the rebalance process by modifying its power to 6, 8, 10

SQL> alter diskgroup DATA1 rebalance power 10;

After every restart, the diskgroup rebalance again but has the same issue, never end.Here is the content in the alert log

NOTE: starting rebalance of group 1/0x9d2529a0 (DATA1) at power 5
Starting background process ARB0
Fri Sep 16 12:01:11 2011
ARB0 started with pid=15, OS id=21066
Starting background process ARB1
Starting background process ARB2
Fri Sep 16 12:01:11 2011
[code]....

As you can see, the rebalance process started 3 days ago, hanging till now

SQL> select group_number, operation, state, power, est_minutes from v$asm_operation;

GROUP_NUMBER OPERA STAT POWER EST_MINUTES
------------ ----- ---- ---------- -----------
1 REBAL RUN 5 0