环境：
os:rhel6.8
db:11.2.0.4 rac

报错如下：

SQL> alter diskgroup DATA_DG mount;
alter diskgroup DATA_DG mount
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15020: discovered duplicate ASM disk “DATA_DG_0004”

alert日志：
NOTE: cache registered group DATA_DG number=1 incarn=0xfde8ae6a
NOTE: cache began mount (first) of group DATA_DG number=1 incarn=0xfde8ae6a
NOTE: Assigning number (1,5) to disk (/dev/raw/raw15)
NOTE: Assigning number (1,4) to disk (/dev/raw/raw14)
NOTE: Assigning number (1,3) to disk (/dev/raw/raw13)
NOTE: Assigning number (1,1) to disk (/dev/raw/raw11)
NOTE: Assigning number (1,0) to disk (/dev/raw/raw10)
NOTE: Assigning number (1,7) to disk (/dev/raw/raw9)
NOTE: Assigning number (1,8) to disk (/dev/raw/raw6)
NOTE: Assigning number (1,6) to disk (/dev/raw/raw4)
NOTE: Disk in mode 0x9 marked for de-assignment
NOTE: cache dismounting (clean) group 1/0xFDE8AE6A (DATA_DG)
NOTE: messaging CKPT to quiesce pins Unix process pid: 23674, image: oracle@gwtxdb1 (TNS V1-V3)
NOTE: dbwr not being msg’d to dismount
NOTE: lgwr not being msg’d to dismount
NOTE: cache dismounted group 1/0xFDE8AE6A (DATA_DG)
NOTE: cache ending mount (fail) of group DATA_DG number=1 incarn=0xfde8ae6a
NOTE: cache deleting context for group DATA_DG 1/0xfde8ae6a
Mon May 31 17:08:24 2021
GMON dismounting group 1 at 11 for pid 24, osid 23674
NOTE: Disk DATA_DG_0000 in mode 0x9 marked for de-assignment
NOTE: Disk DATA_DG_0001 in mode 0x9 marked for de-assignment
NOTE: Disk DATA_DG_0003 in mode 0x9 marked for de-assignment
NOTE: Disk DATA_DG_0004 in mode 0x9 marked for de-assignment
NOTE: Disk DATA_DG_0005 in mode 0x9 marked for de-assignment
NOTE: Disk DATA_DG_0007 in mode 0x9 marked for de-assignment
NOTE: Disk DATA_DG_0006 in mode 0x9 marked for de-assignment
ERROR: diskgroup DATA_DG was not mounted
ORA-15032: not all alterations performed
ORA-15020: discovered duplicate ASM disk “DATA_DG_0004”
ERROR: alter diskgroup DATA_DG mount

磁盘查询：

GROUP_NUMBER FREE_MB TOTAL_MB FAILGROUP DISK_NUMBER MOUNT_S MODE_ST STATE HEADER_STATU NAME PATH

   2	   4776       5120 OCR_DG_0000		     0 CACHED  ONLINE  NORMAL	MEMBER	     OCR_DG_0000     /dev/raw/raw1
   2	   4792       5120 OCR_DG_0002		     2 CACHED  ONLINE  NORMAL	MEMBER	     OCR_DG_0002     /dev/raw/raw3
   2	   4780       5120 OCR_DG_0004		     4 CACHED  ONLINE  NORMAL	MEMBER	     OCR_DG_0004     /dev/raw/raw5
   2	   4784       5120 OCR_DG_0006		     6 CACHED  ONLINE  NORMAL	MEMBER	     OCR_DG_0006     /dev/raw/raw7
   0	      0 	 0			     0 IGNORED ONLINE  NORMAL	MEMBER			     /dev/raw/raw16
   0	      0 	 0			     1 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw15
   0	      0 	 0			     2 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw14
   0	      0 	 0			     3 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw13
   0	      0 	 0			     4 IGNORED ONLINE  NORMAL	MEMBER			     /dev/raw/raw12
   0	      0 	 0			     5 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw11
   0	      0 	 0			     6 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw10
   0	      0 	 0			     7 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw9
   0	      0 	 0			     8 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw8
   0	      0 	 0			     9 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw6
   0	      0 	 0			    10 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw4
   0	      0 	 0			    14 CLOSED  ONLINE  NORMAL	MEMBER			     /dev/raw/raw2

16 rows selected.