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why we use crosscheck, obsolete , restore validate in rman?

1. why we use crosscheck command in rman ? 2. why we use obsolete command in rman ? 3. why we go for restore database validate ? Solution : .1. To check whether backups are physically available2. To check whether backups are valid (redundant)3. To check the existing backup pieces are valid to restore  

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What is meant by incremental,cumulative and complete backups?

Full BackupsA full backup is different from a whole database backup. A full data file backup is a backup that includes every used data block in the file. RMAN copies all blocks into the backup set or image copy, skipping only data file blocks that have never been used. For a full image copy, the … continue reading

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how to find current size, available size, used size and total size in a Tablespace .

For used size: select sum(bytes) from dba_segments where tablespace_name=”; For available size: select sum(bytes) from dba_datafiles where tablespace_name=”; select df.tablespace_name “Tablespace”, totalusedspace “Used MB”, (df.totalspace – tu.totalusedspace) “Free MB”, df.totalspace “Total MB”, round(100 * ( (df.totalspace – tu.totalusedspace)/ df.totalspace)) “Pct. Free” from (select tablespace_name, round(sum(bytes) / 1048576) TotalSpace from dba_data_files where tablespace_name like ‘%xxxxxxxxxxxxxx%’ group … continue reading

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Why expdp is faster than regular exp?

Solutions: 1. expdp is faster due to parallelism. 2. expdp is more advanced. 3. expdp is direct path export which is Oracle Data block. Exp uses SQL level extraction. 4. Exp,imp runs on client side, but expdp and impdp runs on server side.so we have much control compared to traditional exp,imp !  

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How to know log sequence number/SCN of Archive log file for restoration purpose

Possible Solutions: select * from v$log; select sequence# from v$archived_log; RMAN>RESTORE DATABASE PREVIEW  

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Recovery – Loss of all control files (no catalog)

SCENARIO – LOSS OF ALL CONTROLFILES (NO CATALOG) SQL> insert into myobjects select * from myobjects; 919664 rows created. SQL> commit; Commit complete. SQL> select count(*) from myobjects; COUNT(*) ———- 1839328 >>>> need to check this record count after recovery SQL> archive log list Database log mode Archive Mode Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST … continue reading

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Recovery from complete loss of all online redo log files using RMAN

Recovery from complete loss of all online redo log files using RMAN: Database name and version SQL> select instance_name,version from v$instance; INSTANCE_NAME VERSION —————- —————– opsdba 10.2.0.2.0 SQL> select member from v$Logfile; MEMBER ——————————- /u02/ORACLE/opsdba/redo03.log /u02/ORACLE/opsdba/redo02.log /u02/ORACLE/opsdba/redo01.log Lets delete all the redo log files , from the above specified location i.e /u02/ORACLE/ opsdba:/u02/ORACLE/opsdba>rm redo*.log If … continue reading

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