ORA-7445 Internal Error

An ORA-7445 is a generic error, and can occur from anywhere in the Oracle code. The precise location of the error is identified by the core file and/or trace file it produces. Whenever an ORA-7445 error is raised a core file is generated. There may be a trace file generated with the error as well.

Prior to 11g, the core files are located in the CORE_DUMP_DEST directory. Starting with 11g, there is a new advanced fault diagnosability infrastructure to manage trace data. Diagnostic files are written into a root directory for all diagnostic data called the ADR home. Core files at 11g will go to the ADR HOME/cdump directory

For more Indispensability check the below :

1. Check the Alert Log  :    The alert log may indicate additional errors or other internal errors at the time of the problem. In some cases, the ORA-7445 error will occur along with ORA-600, ORA-3113, ORA-4030 errors. The ORA-7445 error can be side effects of the other problems and we should review the first error and associated core file or trace file and work down the list of errors. 

If the ORA-7445 errors are not associated with other error conditions, ensure the trace data is not truncated. If we see a message at the end of the file “MAX DUMP FILE SIZE EXCEEDED" . the MAX_DUMP_FILE_SIZE parameter is not setup high enough or to ‘unlimited’. There could be vital diagnostic information missing in the file and discovering the root issue may be very difficult. Set the MAX_DUMP_FILE_SIZE appropriately and regenerate the error for complete trace information.

2. Search 600/7445 Lookup Tool  :  Visit My Oracle Support to access the ORA-00600 Lookup tool (Note 7445.1). The ORA-600/ORA-7445 Lookup tool may lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or we  can pull out key stack pointers from the associated trace file to match up against known bugs.

3. “Fine tune” searches in Knowledge Base  :   As the ORA-7445 error indicates an unhandled exception in the Oracle source code, our search in the Oracle Knowledge Base will need to focus on the stack data from the core file or the trace file.

Keep in mind that searches on generic argument data will bring back a large result set . The more we can learn about the environment and code leading to the errors, the easier it will be to narrow the hit list to match our problem.

4  .  If assistance is required from Oracle  :    Should it become necessary to get assistance from Oracle Support on an ORA-7445 problem, please provide at a minimum, the 

• Alert log
• Associated tracefile(s) or incident package at 11g
• Patch level information
• Core file(s)
• Information about changes in configuration and/or application prior to issues
• If error is reproducible, a self-contained reproducible testcase: Note.232963.1 How to Build a Testcase for Oracle Data Server Support to Reproduce ORA-600 and ORA-7445 Errors.
• RDA report or Oracle Configuration Manager information

Enjoy     :-) 

Estimate the Optimal UNDO Tablespace size in Oracle

We can size the undo tablespace appropriately either by using automatic extension of the undo tablespace or by using the Undo Advisor for a fixed sized tablespace.If we have decided on a fixed-size undo tablespace, the Undo Advisor can help us to estimate needed capacity.The Undo Advisor relies for its analysis on data collected in the Automatic Workload Repository (AWR). It is therefore important that the AWR have adequate workload statistics available so that the Undo Advisor can make accurate recommendations. 

Below is the script which will estiate the size of the undo tablespace required and also provide the detail when the database face the Number of "ORA-01555 (Snapshot too old)" encountered since the last startup of the instance 

SQL> SELECT  d.undo_size/(1024*1024) “ACTUAL UNDO SIZE [MByte]“,
                        SUBSTR(e.value,1,25) “UNDO RETENTION [Sec]“,
                       (TO_NUMBER(e.value) * TO_NUMBER(f.value) *
                      g.undo_block_per_sec) / (1024*1024)  “NEEDED UNDO SIZE [MByte]“
  FROM        (SELECT SUM(a.bytes) undo_size  FROM v$datafile a,  v$tablespace b,
                     dba_tablespaces c
 WHERE      c.contents = 'UNDO'
 AND          c.status = 'ONLINE'
 AND          b.name = c.tablespace_name
AND           a.ts# = b.ts#  ) d, v$parameter e, v$parameter f,
                 ( SELECT MAX(undoblks/((end_time-begin_time)*3600*24))  undo_block_per_sec
FROM       v$undostat  ) g 
WHERE      e.name = 'undo_retention'
AND         f.name = 'db_block_size'
/
set feedback off
set heading off
set lines 132
declare
  cursor get_undo_stat is
         select d.undo_size/(1024*1024) "C1",
                substr(e.value,1,25)    "C2",
                (to_number(e.value) * to_number(f.value) *
g.undo_block_per_sec) / (1024*1024) "C3",
                round((d.undo_size / (to_number(f.value) *
g.undo_block_per_sec)))             "C4"
           from (select sum(a.bytes) undo_size
                   from v$datafile      a,
                        v$tablespace    b,
                        dba_tablespaces c
                  where c.contents = 'UNDO'
                    and c.status = 'ONLINE'
                    and b.name = c.tablespace_name
                    and a.ts# = b.ts#)  d,
                v$parameter e,
                v$parameter f,
                (select max(undoblks/((end_time-begin_time)*3600*24))
undo_block_per_sec from v$undostat)  g
          where e.name = 'undo_retention'
            and f.name = 'db_block_size';
begin
dbms_output.put_line(chr(10)||chr(10)||chr(10)||chr(10) ||
'To optimize UNDO we have two choices :');
dbms_output.put_line('==========================================' || chr(10));
  for rec1 in get_undo_stat loop
      dbms_output.put_line('A)
Adjust UNDO tablespace size according to UNDO_RETENTION :'
|| chr(10));
      dbms_output.put_line(rpad('ACTUAL UNDO SIZE ',65,'.')|| ' : ' ||
TO_CHAR(rec1.c1,'999999') || ' MEGS');
      dbms_output.put_line(rpad('OPTIMAL UNDO SIZE WITH ACTUAL UNDO_RETENTION
(' || ltrim(TO_CHAR(rec1.c2/60,'999999'))
 || ' MINUTES)
',65,'.') || ' : ' || TO_CHAR(rec1.c3,'999999') || ' MEGS');
      dbms_output.put_line(chr(10));
      dbms_output.put_line('B) Adjust UNDO_RETENTION according to UNDO tablespace size :'
|| chr(10));
      dbms_output.put_line(rpad('ACTUAL UNDO RETENTION ',65,'.') ||
' : ' || TO_CHAR(rec1.c2/60,'999999') || ' MINUTES');
      dbms_output.put_line(rpad('OPTIMAL UNDO RETENTION WITH ACTUAL UNDO SIZE
(' || ltrim(TO_CHAR(rec1.c1,'999999')) || ' MEGS) ',65,'.') || ' : ' ||
TO_CHAR(rec1.c4/60,'999999') || ' MINUTES');
  end loop;
dbms_output.put_line(chr(10)||chr(10));
end;
/
select 'Number of "ORA-01555 (Snapshot too old)" encountered since
the last startup of the instance : ' || sum(ssolderrcnt)
from v$undostat;


Enjoy   :-) 

How to resize redolog file in oracle

Once , i receive the e-mail regarding the resize of the redo log file . The Sender want the easiest way to size the redo log file something like 'alter database logfile group 1 '?\redo01.log resize 100m '  or using some other trick . 

We cannot resize the redo log files. We must drop the redolog file and recreate them .This is only method to resize the redo log files. A database requires atleast two groups of redo log files,regardless the number of the members. We cannot the drop the redo log file if its status is current or active . We have change the status to "inactive" then only we can drop it.

When a redo log member is dropped from the database, the operating system file is not deleted from disk. Rather, the control files of the associated database are updated to drop the member from the database structure. After dropping a redo log file, make sure that the drop completed successfully, and then use the appropriate operating system command to delete the dropped redo log file. In my case i have four redo log files and they are of 50MB in size .I will resize to 100 MB.  Below are steps to resize the redo log files.

Step 1 : Check the Status of Redo Logfile 
SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#  SEQUENCE#      BYTES    ARC    STATUS
----------    ----------    ----------      -----       -------------
         1          5   52428800      YES          INACTIVE
         2          6   52428800      YES          ACTIVE
         3          7   52428800      NO          CURRENT
         4          4   52428800     YES          INACTIVE

Here,we cannot drop the current and active redo log file .

Step  2 :  Forcing a Checkpoint  :

The SQL statement alter system checkpoint explicitly forces Oracle to perform a checkpoint for either the current instance or all instances. Forcing a checkpoint ensures that all changes to the database buffers are written to the datafiles on disk .A global checkpoint is not finished until all instances that require recovery have been recovered.

SQL> alter system checkpoint global ;
system altered.

SQL> select group#,sequence#,bytes,archived,status from v$log;

    GROUP#    SEQUENCE#        BYTES    ARC       STATUS
----------    ----------    ----------    -----     ----------------
         1          5       52428800     YES      INACTIVE
         2          6      52428800     YES       INACTIVE
         3          7      52428800     NO       CURRENT
         4          4      52428800    YES       INACTIVE
Since the status of group 1,2,4 are inactive .so we will drop the group 1 and group 2 redo log file.

Step  3  :  Drop Redo Log File : 
SQL> alter database drop logfile group 1;
Database altered.

SQL> alter database drop logfile group 2;
Database altered.

SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#  SEQUENCE#      BYTES    ARC    STATUS
----------    ----------    ----------    ---     ----------------
         3          7               52428800      NO       CURRENT
         4          4             52428800       YES      INACTIVE

Step  4  : Create new redo log file 

If we don't delete the old redo logfile by OS command when creating the log file with same name then face the below error . Therefore to solve it delete the file by using OS command .

SQL> alter database add logfile group 1 'C:\app\neerajs\oradata\orcl\redo01.log' size 100m;
alter database add logfile group 1 'C:\app\neerajs\oradata\orcl\redo01.log' size 100m
*
ERROR at line 1:
ORA-00301: error in adding log file 'C:\app\neerajs\oradata\orcl\redo01.log' - file cannot be created
ORA-27038: created file already exists
OSD-04010: <create> option specified, file already exists

SQL> alter database add logfile group 1 'C:\app\neerajs\oradata\orcl\redo01.log' size 100m;
Database altered.

SQL> alter database add logfile group 2 'C:\app\neerajs\oradata\orcl\redo02.log' size 100m;
Database altered.

SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#      SEQUENCE#      BYTES     ARC       STATUS
----------    ----------     ----------       ---      ----------------
         1          0      104857600       YES     UNUSED
         2          0      104857600       YES     UNUSED
         3          7       52428800        NO      CURRENT
         4          4       52428800       YES      INACTIVE

Step 5 :  Now drop the remaining two old redo log file 
SQL> alter system switch logfile ;
System altered.

SQL> alter system switch logfile ;
System altered.

SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#  SEQUENCE#      BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
         1          8  104857600     YES     ACTIVE
         2          9  104857600     NO      CURRENT
         3          7   52428800     YES     ACTIVE
         4          4   52428800     YES     INACTIVE

SQL> alter system checkpoint global;
System altered.

SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#  SEQUENCE#      BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
         1          8    104857600     YES     INACTIVE
         2          9    104857600     NO     CURRENT
         3          7     52428800     YES     INACTIVE
         4          4     52428800    YES      INACTIVE

SQL> alter database drop logfile group 3;
Database altered.

SQL> alter database drop logfile group 4;
Database altered.

SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#  SEQUENCE#      BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
         1          8  104857600      YES      INACTIVE
         2          9  104857600      NO       CURRENT

Step 6 : Create the redo log file 
SQL> alter database add logfile group 3 'C:\app\neerajs\oradata\orcl\redo03.log' size 100m;
Database altered.

SQL> alter database add logfile group 4 'C:\app\neerajs\oradata\orcl\redo04.log' size 100m;
Database altered.

SQL>  select group#,sequence#,bytes,archived,status from v$log;
    GROUP#  SEQUENCE#      BYTES ARC STATUS
---------- ---------- ---------- --- ----------------
         1          8        104857600      YES       INACTIVE
         2          9        104857600      NO        CURRENT
         3          0        104857600     YES        UNUSED
         4          0        104857600     YES        UNUSED


Enjoy    :-)