startup ksfdopn ora-17503 invalid username/password ora-01017

I'm thinking of taking the Oracle 12c OCP exam (IZO-060), and I have started by setting up a Centos 5.8 with Oracle 12c using an ASM disk array:

http://wiki.ebabel.eu/index.php/oracle_asm_standalone

This was up and running apparently smoothly (using runInstaller and dbca), but when I tried my first restart, the shutdown was OK, but on restarting startup:

SQL> startup

ORA-01078: failure in processing system parameters

ORA-01565: error in identifying file '+DATA/orcl12c/spfileorcl12c.ora'

ORA-17503: ksfdopn:2 Failed to open file +DATA/orcl12c/spfileorcl12c.ora

ORA-15056: additional error message

ORA-17503: ksfdopn:2 Failed to open file +DATA/orcl12c/spfileorcl12c.ora

ORA-01017: invalid username/password; logon denied

ORA-06512: at line 4


After googling for ("startup ksfdopn ora-17503") I found reference to the Oracle Support Doc ID 1922050.1, the keep part being:

After the Grid Infrastructure (GI) upgrade, database fail to start with ORA-01017 due to wrong group setup (Doc ID 1922050.1)

If the new asm admin group is asmadmin and the database starts as user oracle (the user oracle also belongs to dba and oinstall group), then issue "usermod -G asmadmin,oinstall,dba oracle" to add asmadmin group to user oracle and then issue id as user oracle to confirm the change.

Checking my permission, they appeared wrong according to the Oracle Support doc:

[root@ora12asm vagrant]# id oracle

uid=2000(oracle) gid=2000(oracle) groups=2000(oracle),1000(oinstall)

[root@ora12asm vagrant]# id oragrid

uid=2001(oragrid) gid=1000(oinstall) groups=1000(oinstall),2001(asmadmin),2002(asmoper),2003(asmdba)

so I followed the instructions:

[root@ora12asm vagrant]# /usr/sbin/usermod -G oinstall,asmdba,asmadmin,asmoper oracle

[root@ora12asm vagrant]# id oracle

uid=2000(oracle) gid=2000(oracle) groups=2000(oracle),1000(oinstall),2001(asmadmin),2002(asmoper),2003(asmdba)


However I got the same startup ksfdopn ora-17503 / ora-01017 errors!?

After some further research the solution was to fix the gid and not just the GID:

[root@ora12asm vagrant]# /usr/sbin/usermod -g oinstall -G asmdba,asmadmin,asmoper oracle

[root@ora12asm vagrant]# id oracle

uid=2000(oracle) gid=1000(oinstall) groups=1000(oinstall),2001(asmadmin),2002(asmoper),2003(asmdba)

I'm not sure if because in Oracle 12c, these Linux OS groups are stricter/slightly different?