在grid用户下，主要通过user_dump_dest查看日志/u01/app/oracle/diag/asm/+asm/+ASM1/trace中的alert_+文件
SQL> show parameter user_dump_dest
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
user_dump_dest string /u01/app/oracle/diag/asm/+asm/
+ASM1/trace
如下内容：
GMON dismounting group 1 at 7 for pid 29, osid 13935
NOTE: Disk in mode 0x8 marked for de-assignment
SUCCESS: diskgroup BSQQNS was dismounted
NOTE: cache deleting context for group BSQQNS 1/0xdec97b2f
SUCCESS: ALTER DISKGROUP BSQQNS DISMOUNT /* asm agent *//* {1:2802:16425} */
SQL> ALTER DISKGROUP DATA DISMOUNT /* asm agent *//* {1:2802:16425} */
Tue Nov 05 22:03:39 2013
GMON querying group 2 at 8 for pid 19, osid 13589
Tue Nov 05 22:03:39 2013
NOTE: Instance updated to 11.2.0.0.0 for grp 2
Tue Nov 05 22:03:39 2013
ORA-15032: not all alterations performed
ORA-15027: active use of diskgroup "DATA" precludes its dismount
ERROR: ALTER DISKGROUP DATA DISMOUNT /* asm agent *//* {1:2802:16425} */
Tue Nov 05 22:03:49 2013
SQL> ALTER DISKGROUP DATA DISMOUNT /* asm agent *//* {1:2802:16425} */
Tue Nov 05 22:03:50 2013
freeing rdom 1
Received detach msg from inst 2 for dom 1
Tue Nov 05 22:03:59 2013
GMON querying group 2 at 9 for pid 19, osid 13589
Tue Nov 05 22:03:59 2013
NOTE: Instance updated to 11.2.0.0.0 for grp 2
Tue Nov 05 22:03:59 2013
ORA-15032: not all alterations performed
ORA-15027: active use of diskgroup "DATA" precludes its dismount
ERROR: ALTER DISKGROUP DATA DISMOUNT /* asm agent *//* {1:2802:16425} */
Tue Nov 05 22:04:09 2013
SQL> ALTER DISKGROUP DATA DISMOUNT /* asm agent *//* {1:2802:16425} */