Tag: blocking

Find blocking sessions In Oracle

Posted on by Osama Mustafa in Database
  You can query the gv$lock and gv$session views to locate a blocking session in RAC.

Miladin Modrakovic offers this script to detect and kill RAC blocking sessions, using  GV$Session and GV$Lock.

 CREATE OR REPLACE PROCEDURE kill_blocker
AS
   sqlstmt   VARCHAR2 (1000);
BEGIN
   FOR x IN (SELECT gvh.SID sessid, gvs.serial# serial,
                    gvh.inst_id instance_id
               FROM gv$lock gvh, gv$lock gvw, gv$session gvs
              WHERE (gvh.id1, gvh.id2) IN (SELECT id1, id2
                                             FROM gv$lock
                                            WHERE request = 0
                                           INTERSECT
                                           SELECT id1, id2
                                             FROM gv$lock
                                            WHERE lmode = 0)
                AND gvh.id1 = gvw.id1
                AND gvh.id2 = gvw.id2
                AND gvh.request = 0
                AND gvw.lmode = 0
                AND gvh.SID = gvs.SID
                AND gvh.inst_id = gvs.inst_id)
   LOOP
      sqlstmt :=
            ‘ALTER SYSTEM KILL SESSION ”’
         || x.sessid
         || ‘,’
         || x.serial
         || ‘,@’
         || x.instance_id
         || ””;
      DBMS_OUTPUT.put_line (sqlstmt);

      EXECUTE IMMEDIATE sqlstmt;
   END kill_blovk;
END TEST;
/         

when the script  will generate it will execute Alter session to kill This Session .

Some Useful Link : 
1-Erik Wramner

Thank you
Osama mustafa
 

 

Automatic Storage Management/ASM Part 2

Posted on by Osama Mustafa in Database

Templates:

Templates are named groups of attributes that can be applied to the files within a disk group

Examples :

 

-- Create a new template.
ALTER DISKGROUP disk_group_1 ADD TEMPLATE my_template ATTRIBUTES (MIRROR FINE);

-- Modify template.
ALTER DISKGROUP disk_group_1 ALTER TEMPLATE my_template ATTRIBUTES (COARSE);

-- Drop template.
ALTER DISKGROUP disk_group_1 DROP TEMPLATE my_template;

Available attributes include:

  • UNPROTECTED – No mirroring or striping regardless of the redundancy setting.
  • MIRROR – Two-way mirroring for normal redundancy and three-way mirroring for high redundancy. This attribute cannot be set for external redundancy.
  • COARSE – Specifies lower granuality for striping. This attribute cannot be set for external redundancy.
  • FINE – Specifies higher granularity for striping. This attribute cannot be set for external redundancy.

 

 

Directories

A directory heirarchy can be defined using the ALTER DISKGROUP statement to support ASM file aliasing

Examples :

-- Create a directory.
ALTER DISKGROUP disk_group_1 ADD DIRECTORY '+disk_group_1/my_dir';

-- Rename a directory.
ALTER DISKGROUP disk_group_1 RENAME DIRECTORY '+disk_group_1/my_dir' TO '+disk_group_1/my_dir_2';

-- Delete a directory and all its contents.
ALTER DISKGROUP disk_group_1 DROP DIRECTORY '+disk_group_1/my_dir_2' FORCE;

 

Aliases

Aliases allow you to reference ASM files using user-friendly names

-- Create an alias using the fully qualified filename.
ALTER DISKGROUP disk_group_1 ADD ALIAS '+disk_group_1/my_dir/my_file.dbf'
  FOR '+disk_group_1/mydb/datafile/my_ts.342.3';

-- Create an alias using the numeric form filename.
ALTER DISKGROUP disk_group_1 ADD ALIAS '+disk_group_1/my_dir/my_file.dbf'
  FOR '+disk_group_1.342.3';

-- Rename an alias.
ALTER DISKGROUP disk_group_1 RENAME ALIAS '+disk_group_1/my_dir/my_file.dbf'
  TO '+disk_group_1/my_dir/my_file2.dbf';

-- Delete an alias.
ALTER DISKGROUP disk_group_1 DELETE ALIAS

Files

Files are not deleted automatically if they are created using aliases, as they are not Oracle Managed Files (OMF), or if a recovery is done to a point-in-time before the file was created. For these circumstances it is necessary to manually delete the files, as shown below.

 

-- Drop file using an alias.
ALTER DISKGROUP disk_group_1 DROP FILE '+disk_group_1/my_dir/my_file.dbf';

-- Drop file using a numeric form filename.
ALTER DISKGROUP disk_group_1 DROP FILE '+disk_group_1.342.3';

-- Drop file using a fully qualified filename.
ALTER DISKGROUP disk_group_1 DROP FILE '+disk_group_1/mydb/datafile/my_ts.342.3';

ASM Views:

Migrating to ASM Using RMAN:

  • Disable change tracking (only available in Enterprise Edition) if it is currently being used.
SQL> ALTER DATABASE DISABLE BLOCK CHANGE TRACKING;
  • Shutdown the database.
    SQL> SHUTDOWN IMMEDIATE 
    • Modify the parameter file of the target database as follows:
      Set the DB_CREATE_FILE_DEST and DB_CREATE_ONLINE_LOG_DEST_n parameters to the relevant ASM disk groups.
      Remove the CONTROL_FILES parameter from the spfile so the control files will be moved to the DB_CREATE_* destination and the spfile gets updated automatically. If you are using a pfile the CONTROL_FILES parameter must be set to the appropriate ASM files or aliases.
  • Start the database in nomount mode.

                            RMAN> STARTUP NOMOUNT

 

  • Restore the controlfile into the new location from the old location.

 RMAN> RESTORE CONTROLFILE FROM ‘old_control_file_name’;

  • Mount the database.
  • Copy the database into the ASM disk group.
    RMAN> BACKUP AS COPY DATABASE FORMAT '+disk_group';

  • Switch all datafile to the new ASM location.

    RMAN> SWITCH DATABASE TO COPY;
  • Open the database.

    RMAN> ALTER DATABASE OPEN;
  • Create new redo logs in ASM and delete the old ones.
  • Enable change tracking if it was being used.

    SQL> ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;