ORA-15025:could not open disk “/dev/12casm-diskb” 解决方法
数据库升级后，数据库报错ORA-15025，数据库无法启动。
alert日志信息：
Wed Jul22 16:26:57 2015
ORA-15025:could not open disk "/dev/12casm-diskb"
ORA-27041:unable to open file
Linux-x86_64Error: 13: Permission denied
Additionalinformation: 9
ORA-15040:diskgroup is incomplete
ORA-15040:diskgroup is incomplete
ORA-15040:diskgroup is incomplete
ORA-15040:diskgroup is incomplete
Wed Jul22 16:26:57 2015
ORA-15025:could not open disk "/dev/12casm-diskc"
ORA-27041:unable to open file
Linux-x86_64Error: 13: Permission denied
Additionalinformation: 9
Wed Jul22 16:26:57 2015
ORA-15025:could not open disk "/dev/12casm-diskd"
ORA-27041:unable to open file
Linux-x86_64Error: 13: Permission denied
Additionalinformation: 9
Wed Jul22 16:26:57 2015
ORA-15025:could not open disk "/dev/12casm-diske"
ORA-27041:unable to open file
Linux-x86_64Error: 13: Permission denied
Additionalinformation: 9
NOTE:Disk 0 in group 1 could not be opened.
WARNING:Failed to complete group 1
WARNING:group 1 is being dismounted.
WARNING:ASMB force dismounting group 1 (DATA) due to failed mount
SUCCESS:diskgroup DATA was dismounted
按理来说asm的磁盘文件用户和组为grid:asmadmin，Oracle用户是没有权限访问的，因为oracle不属于asmadmin。
那为什么打补丁之前能够访问呢？
Cause：
经研究发现，这跟$ORACLE_HOME/bin/oracle这个文件的属性有关系：
在安装oracle soft之后：
$ORACLE_HOME/bin/oracle文件属性权限为oracle:oninstall 751(-rwxr-x--x)
在用安装ASM建库(DBCA)时：
此文件属性会自动被修改为oracle:asmadmin6751(-rwsr-s--x)
在升级之后：
此文件属性又被自动被修改为oracle:oinstall751(-rwxr-x--x)
Solution:
chown oracle:asmadmin $ORACLE_HOME/bin/oracle
chmod 6751 $ORACLE_HOME/bin/oracle
问题解决！