ORA-17503 ORA-27140 ORA-27300 ORA-27301 ORA-27302

ORA-00210: cannot open the specified control file
ORA-00202: control file: '+DATA/mydb/controlfile/current.257.918811113'
ORA-17503: ksfdopn:2 Failed to open file +DATA/mydb/controlfile/current.257.918811113
ORA-15001: diskgroup "DATA" does not exist or is not mounted
ORA-15055: unable to connect to ASM instance
ORA-27140: attach to post/wait facility failed
ORA-27300: OS system dependent operation:invalid_egid failed with status: 1
ORA-27301: OS failure message: Operation not permitted
ORA-27302: failure occurred at: skgpwinit6
ORA-27303: additional information: startup egid = 1000 (oinstall), current egid = 1031 (dba)
ORA-00210: cannot open the specified control file
ORA-00202: control file: '+DATA/mydb/controlfile/current.256.918811111'
ORA-17503: ksfdopn:2 Failed to open file +DATA/mydb/controlfile/current.256.918811111
ORA-15001: diskgroup "DATA" does not exist or is not mounted
ORA-15055: unable to connect to ASM instance
ORA-27140: attach to post/wait facility failed
ORA-27300: OS system dependent operation:invalid_egid failed with status: 1
ORA-27301: OS failure message: Operation not permitted
ORA-27302: failure occurred at: skgpwinit6
ORA-27303: additional information: startup egid = 1000 (oinstall), current egid = 1031 (dba)

If you are trying to start database and it is failing with above errors even though ASM instance is running and ASM diskgroup is also mounted perfectly, is probably related to permissions on oracle executable under GRID_HOME. Following is the current permissions (highlighted in red) and how to change permissions to the correct value (highlighted in green)

[oracle]$ cd $GRID_HOME/bin [oracle]$ ls -l oracle -rwxrwxr-x. 1 oracle oinstall 209914513 Jul 11  2016 oracle [oracle]$ chmod 6751 oracle [oracle]$ ls -l oracle -rwsr-s--x. 1 oracle oinstall 209914513 Jul 11  2016 oracle [oracle]$

After fixing the permissions, you should be able to start database successfully.