Tip

Automating hot backups

This script (which obviously must be run by a DBA) automates hot backups. It assumes an underlying UNIX system, and the use of the 'cp' command to backup the files to a special backup directory the name of which is prompted for in the script. The script can easily be modified to take other assumptions into account. It is distributed in the hope that it will be useful for other database administrators performing their extremely imporatant backup and recovery tasks.

set linesize 600
set pause off
set pagesize 0
set echo off
set feedback off
--
--  Hot-backup requires our running in ARCHIVELOG mode.
--  This is tested from the outset. 
--
whenever sqlerror exit sql.sqlcode
declare
   dummy char(1);
begin
   select 'x'
   into dummy
   from v$database
   where log_mode = 'ARCHIVELOG';
exception
   when no_data_found then
      raise_application_error(-20000, 'Database not in ARCHIVELOG mode !');
end;
/
set scan off
--
--   Interactively input the name of the directory (or device)
--   where to backup. This kind of dialogue is likely to prove
--   a hindrance in automated, daily operations.
--   You can either hard-code the directory name by using
--      define backup_dir = ...
--   or suppose it is passed as an argument to the current
--   script, in which case you should replace &&backup_dir by
--   &1 everywhere in this script and comment the following
--   'accept' command
--
accept backup_dir prompt 'Backup directory : '
--
set recsep off
set scan on
set verify

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off -- -- You must absolutely check that everything goes according -- to plans! If the backup fails because of, say, a -- 'file system full' error, the script must exit with a -- non-0 return code. -- whenever sqlerror exit sql.sqlcode whenever oserror exit 99 -- -- To be certain we have a consistent set of files which -- we shall be able to recover, we also want to backup -- all the redo log files generated during the backup, -- and the final state of the control file. -- Note that when recovering you normally must use the -- current (i.e. at crash time) control file. However, -- we want to be ready for the worst case scenario and -- be able to use the current backup as if it were a -- cold backup. -- In order to know which redo log files have been generated -- during the backup, we first identify which is, before -- backup, the (current - 1) redo log file. -- variable last_log varchar2(255) begin -- -- Format %S and %T (left-padded with zeros) -- are not supported because length is OS-dependent. -- Easy to support for a specific machine -- select replace(pd.value, '?', '$ORACLE_HOME') || replace(replace(pf.value, '%s', rtrim(to_char(l.sequence#))), '%t', rtrim(to_char(l.thread#))) into :last_log from v$parameter pd, v$parameter pf, v$log l where pd.name = 'log_archive_dest' and pf.name = 'log_archive_format' and l.sequence# = (select max(sequence#) from v$log where status != 'CURRENT'); end; / -- -- Generate the backup script -- -- online$ = 3 means a tablespace which once -- existed but was dropped. -- column dummy noprint spool do_hbu.sql select ts# dummy, 1 dummy, 'alter tablespace ' || name || ' begin backup;' from sys.ts$ where online$ != 3 union select f.ts#, 2, 'host cp ' || d.name || ' &&backup_dir' from sys.file$ f, v$datafile d where f.file# = d.file# union select ts#, 3, 'alter tablespace ' || name || ' end backup;' from sys.ts$ where online$ != 3 order by 1, 2 / spool off -- -- Run the backup script just generated -- set echo on set feedback on @do_hbu -- -- Take a backup of the control file for the worst-case scenario -- Do not worry, parameter replacement is not echoed but done. -- alter database backup controlfile to '&&backup_dir./control.ctl' reuse; -- -- Trigger a redo log switch to close the current redo log file -- alter system switch logfile; set echo off -- -- Force the archival of all the redo log files -- declare Stmt varchar2(100); cid number; dummy number; nothing_to_archive exception; PRAGMA EXCEPTION_INIT(nothing_to_archive, -271); begin Stmt := 'alter system archive log all'; cid := dbms_sql.open_cursor; begin dbms_sql.parse(cid, Stmt, dbms_sql.native); dummy := dbms_sql.execute(cid); exception when nothing_to_archive then null; -- -- Unexpected errors -- when others then if (dbms_sql.is_open(cid)) then dbms_sql.close_cursor(cid); end if; raise_application_error(-20000, Stmt || chr(10) || SQLERRM); end; dbms_sql.close_cursor(cid); end; / set feedback off -- -- Backup all the redo log files generated during hot backup -- spool backup_log.sql select 'host find ' || replace(substr(p.value, 1, instr(p.value, '/', -1) - 1), '?', '$ORACLE_HOME') || ' -type f -newer ' || :last_log || ' -exec cp {} &&backup_dir ;' from v$parameter p where p.name = 'log_archive_dest' / spool off set echo on @backup_log -- -- That's all folks. -- exit 0 -------------------------------------- rem Must be run by a DBA. rem rem IT IS EXTREMELY IMPORTANT TO RUN THIS SCRIPT AS SOON AS POSSIBLE rem IN THE EVENT OF FAILURE OF THE hotbackup.sql SCRIPT submitted above. rem -- -- CANCELLING IN-BACKUP STATE ... -- set linesize 100 set pause off set pagesize 0 set echo off set feedback off set recsep off set scan off spool cancel_hbu.sql select 'alter tablespace ' || ts.name || ' end backup;' from sys.ts$ ts where ts.ts# in (select f.ts# from sys.file$ f, v$backup b where f.file# = b.file# and b.status = 'ACTIVE'); spool off set echo on set feedback on @cancel_hbu exit

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This was first published in March 2001

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