在Oracle Linux 7.1中使用dbca为Oracle 18C RAC创建数据库时，找不到ASM磁盘组；而grid用户使用asmca却又能看到ASM磁盘组。
解决方法
1. 检查创建ASM磁盘设备的权限，正确的权限为grid:asmadmin，通过下面输出可知权限正确
[root@18c1 ~]# ls -lrt /dev/asm*
brw-rw---- 1 grid asmadmin 8, 16 Mar 16 22:28 /dev/asmdisk01
brw-rw---- 1 grid asmadmin 8, 32 Mar 17 08:40 /dev/asmdisk02
[root@18c2 ~]# ls -lrt /dev/asm*
brw-rw---- 1 grid asmadmin 8, 32 Mar 17 08:41 /dev/asmdisk02
brw-rw---- 1 grid asmadmin 8, 16 Mar 17 08:41 /dev/asmdisk012.检查ASM实例是否启动
[grid@18c1 ~]$ asmcmd lsdg
State Type Rebal Sector Logical_Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Voting_files Name
MOUNTED EXTERN N 512 512 4096 4194304 61440 35868 0 35868 0 Y CRS/
MOUNTED EXTERN N 512 512 4096 4194304 40960 36036 0 36036 0 N DATA/
[grid@18c2 ~]$ asmcmd lsdg
State Type Rebal Sector Logical_Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Voting_files Name
MOUNTED EXTERN N 512 512 4096 4194304 61440 35868 0 35868 0 Y CRS/
MOUNTED EXTERN N 512 512 4096 4194304 40960 36036 0 36036 0 N DATA/3. 检查GRID_HOME/bin下oracle是否有s权限，如果没有需要添加s权限,通过下面的输出可知GRID_HOME/bin目录下的oracle是没有s权限的，这里需要添加
[root@18c1 ~]# ls -lrt /u01/app/oracle/18.0.0/db/bin/oracle
-rwsr-s--x 1 oracle asmadmin 437038067 Mar 16 23:00 /u01/app/oracle/18.0.0/db/bin/oracle
[root@18c1 ~]# ls -lrt /u01/app/18.0.0/grid/bin/oracle
-rwxr-x--x. 1 grid oinstall 413877125 Mar 16 19:10 /u01/app/18.0.0/grid/bin/oracle
[root@18c2 /]# ls -lrt /u01/app/oracle/18.0.0/db/bin/oracle
-rwsr-s--x 1 oracle oinstall 437038067 Mar 16 23:07 /u01/app/oracle/18.0.0/db/bin/oracle
[root@18c2 /]# ls -lrt /u01/app/18.0.0/grid/bin/oracle
-rwxr-x--x. 1 grid oinstall 413877125 Mar 16 19:30 /u01/app/18.0.0/grid/bin/oracle
[root@18c1 ~]# chmod +s /u01/app/18.0.0/grid/bin/oracle
[root@18c1 ~]# ls -lrt /u01/app/18.0.0/grid/bin/oracle
-rwsr-s--x. 1 grid oinstall 413877125 Mar 16 19:10 /u01/app/18.0.0/grid/bin/oracle
[root@18c2 /]# chmod +s /u01/app/18.0.0/grid/bin/oracle
[root@18c2 /]# ls -lrt /u01/app/18.0.0/grid/bin/oracle
-rwsr-s--x. 1 grid oinstall 413877125 Mar 16 19:30 /u01/app/18.0.0/grid/bin/oracle4.检查用户所有组
[root@18c1 ~]# id oracle
uid=1001(oracle) gid=1011(oinstall) groups=1007(asmdba),1009(dba),1010(oper),1012(backupdba),1013(dgdba),1014(kmdba),1015(racdba),1011(oinstall)
[root@18c1 ~]# id grid
uid=1002(grid) gid=1011(oinstall) groups=1006(asmadmin),1007(asmdba),1008(asmoper),1009(dba),1011(oinstall)
[root@18c1 ~]# gpasswd -a oracle asmadmin
Adding user oracle to group asmadmin
[root@18c1 ~]# id oracle
uid=1001(oracle) gid=1011(oinstall) groups=1006(asmadmin),1007(asmdba),1009(dba),1010(oper),1012(backupdba),1013(dgdba),1014(kmdba),1015(racdba),1011(oinstall)
[root@18c2 /]# id oracle
uid=1001(oracle) gid=1011(oinstall) groups=1007(asmdba),1009(dba),1010(oper),1012(backupdba),1013(dgdba),1014(kmdba),1015(racdba),1011(oinstall)
[root@18c2 /]# id grid
uid=1002(grid) gid=1011(oinstall) groups=1006(asmadmin),1007(asmdba),1008(asmoper),1009(dba),1011(oinstall)
[root@18c2 /]# gpasswd -a oracle asmadmin
Adding user oracle to group asmadmin
[root@18c2 /]# id oracle
uid=1001(oracle) gid=1011(oinstall) groups=1006(asmadmin),1007(asmdba),1009(dba),1010(oper),1012(backupdba),1013(dgdba),1014(kmdba),1015(racdba),1011(oinstall)再执行dbca创建数据库时能正确找到磁盘组
