ORA-01102: and ORA-16014:

SQL> startup pfile='/u01/app/oracle/product/10.2.0/db_1/dbs/initorcl.ora';
ORACLE instance started.
Total System Global Area 83886080 bytes
Fixed Size 1217836 bytes
Variable Size 75500244 bytes
Database Buffers 4194304 bytes
Redo Buffers 2973696 bytes
ORA-01102: cannot mount database in EXCLUSIVE mode
Cause:
Can be that you are trying to startup second instance with privously opened database.
If you have only one database and gets this error then that means you are trying to open an opened database!.


2.
Total System Global Area 83886080 bytes
Fixed Size 1217836 bytes
Variable Size 75500244 bytes
Database Buffers 4194304 bytes
Redo Buffers 2973696 bytes
Database mounted.ORA-16014: log 1 sequence# 188 not archived, no available destinationsORA-00312: online log 1 thread 1: '/u01/app/oracle/pkstg102/redo01.log'

Cause: you archives are of size equal to your database parameter DB_RECOVERY_FILE_DEST_SIZE. get rid of this error just increase this parameter's value.

SQL> alter system set DB_RECOVERY_FILE_DEST_SIZE = 6g;
System altered.
SQL> alter database open;
Database altered.