DB Version:10gR2
OS : AIX 6.0
To test a recovery scenario, i backed up the entire database and deleted the datafile users01.dbf .I thought the db will crash. It didn’t.
select file_name, tablespace_name from dba_data_files where tablespace_name='USERS';
was showing that this file exitsts! I tried few INSERTs, UPDATEs and DELETE with commit. They all worked !!!!!!! Even Create table statements worked.
Then from
1560155
and
1327229
I came to know that this is the expected behaviour in UNIX environments.
My questions:
Question1.
After dropping users01.dbf file , i had performed several DMLs with COMMITs and DDLs. where was the Dbwriter process writing these changes to when there was a checkpoint?
Question 2.
Database became aware of the missing datafile only when i put the datfile offline and then tried to bring it back online.
SQL> alter database datafile 'u07/data/oraqa215/users01.dbf' offline;
Database altered.
SQL> alter database datafile 'u07/data/oraqa215/users01.dbf' online;
alter database datafile 'u07/data/oraqa215/users01.dbf' online
*
ERROR at line 1:
ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
ORA-01110: data file 4:'u07/data/oraqa215/users01.dbf'
Why is the DB still up even after DB became aware that users01.dbf was missing?