Sequence generation in Oracle RAC env. (Cached, non-ordered)

Question

Env: Oracle Env. 11G, Transaction Java Application
How does CACHED, non-ordered sequence behave (for PK generation), here is the scenario,
Cache size =10
Node 1 Active - Records created 1,2,3 (3 records total in table)
Node Changes - 2 is Active - Records created 11,12,13, 14 (7 records total in table)
Node Changes - 1 is Active - Records created 21, 22 (or are sequences going to be 4, 5) (9 records total in table)
Node Changes - 2 is Active - No new record added (9 records total in table)
Node Changes - 1 is Active - 2 more Records created (9 recor11s total in table) - Is it going to be 23, 24 OR or is it going to be 6,7 OR or is it going to be 31, 32 (9 records total in table)
Please help with accurate generated seq numbers (PKs) for 9 records.
Also, What happens to PK numbers at:
* shutdown
* hotbackup
* mirroring whole schema or database to another separate db using storage mirroring
* mirroring whole schema or database to another separate db using datapump
How about using cached, ordered sequences to start with and change to no-order if needed for performance reasons
-D

Answer 1

A necessary problem solving skill in the Oracle environment is the ability to experiment. A couple of minutes constructing a simple test is better than hours of speculation:
jw1> create sequence s1;
Sequence created.
jw1> select s1.nextval from dual;
  NEXTVAL
        1
jw1> /
  NEXTVAL
        2
jw1> conn sys/oracle@jw2 as sysdba
Connected.
jw2> select s1.nextval from dual;
  NEXTVAL
        21
jw2> select s1.nextval from dual;
  NEXTVAL
        22
jw2> conn sys/oracle@jw1 as sysdba
Connected.
jw1> select s1.nextval from dual;
  NEXTVAL
        3
jw1> select s1.nextval from dual;
  NEXTVAL
        4
jw1> exit
Disconnected from Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options
[oracle@berlin1 ~]$ srvctl start instance -db jw -instance jw1 -startoption force
[oracle@berlin1 ~]$ sqlplus sys/oracle@jw1 as sysdba
SQL*Plus: Release 12.1.0.1.0 Production on Sat Aug 16 10:40:40 2014
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options
jw1> select s1.nextval from dual;