2007 RMOUG PAL Presentation

8/8/2019 2007 RMOUG PAL Presentation

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RMAN Disk


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S etupSeparate backup types on RMAN disk bydirectory (eg.)

/RMAN /< SID>_ARCH /RMAN /< SID>_DATA /RMAN /< SID>_C O NTR OL

Init parameters - dynamic (eg.)alter system set control_file_record_keep_time = 30;alter system set archive_lag_target = 900;Init.ora file too!


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E xample of a P OO R Setupcontrol_file_record_keep_time = 5


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Actions:

Ensure other systems are not removing archived logs.Set environment. $ export O RAC LE _SID= $ export O RAC LE _H O ME = $ rman target / nocatalog

Backup archived logs (temporary).run {

allocate channel a1 type disk format'/RMAN /< SID>_ARCH /% d_arch_ % s_ % p_ % c_ % t.rmn';

backupskip inaccessiblearchivelog alltag 'manual_arch'

filesperset 4delete input;}


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(Actions)

Validate Archived logs.$ rman target / nocatalog

run {allocate channel v1 type disk;allocate channel v2 type disk;

allocate channel v type disk;change archivelog all validate;

}

Schedule archive backups.

Set cron for regular level0 backups.Tape backup of RMAN disk .


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P ros All benefits of RMAN!!No need for O racle Agent from tape vendor!!Backups /Restores from disk are faster thantape!!

No need for hot backup mode!!RMAN utility is included with all standard andE nterprise O racle licenses!!

Cons

Your controlfile has limited visibility into thehistory of its backups.Disk is more expensive than tape.


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C orruption Management UsingC orruption Management Using

RMAN With Neither Budget NorRMAN With Neither Budget NorSpace!Space!


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F ACTS

Corruption can, and will, go undetected.Corruption can happen due to many reasons.Chance of corruption can never be eliminated.

The longer corruption goes undetected, themore difficult and potentially costly it is tocorrect /overcome.

D o You Know If You Have Corruption?Are you S ure?


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Wh at Are Your Options To F ind Corruption?select * from < table>;analyze validate structure cascade [online];exp /imp show=yDBVDBMS_R E PAIRInit parameters

db_block_checkingdb_block_compute_checksumdb_block_checksumdb_block_cache_protect=true

_db_block_cache_protect=true _check_block_after_checksum _db_always_check_system_ts

Sum3 rd partyRMAN


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RMAN to find corruption wit h out $$ or spaceWrite Script

$ vi /RMAN /SCRIPTS /level0_validate.ksh

#! /bin/kshexport O RAC LE _SID= export O RAC LE _H O ME=echo "before_time: `date +" %Y% m% d% H% M% S"`"rman target / nocatalog level0_validate.log 2>&1


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NOTE: Log output will N O T indicate corruption found!

Database must be queried after RMAN validate$ vi /RMAN /SCRIPTS /level0_validate.ksh

$ sqlplus ' /as sysdba'

SQ L> select distinct c.file# " F ile#",c.block# "Starting Block#", c.blocks "Range"from v $ backup_corruption c, v $backup_set swhere c.set_stamp = s.set_stampand c.set_count = s.set_countand s.start_time > to_date(&before_time', ' YYYYMMDDHH24MISS')order by 1,2;

Get before_time variable from RMAN validate log$ grep before_time: level0_validate.log


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P ros

You are backing up with RMAN!!Corruption checking as supported and designedby O racle!!

Other than small log files, no additional spacewas used for this system!!No additional cost was incurred!!

Cons

RMAN uses host resources and can take time.This should be during low instance activity.

You are not actually backing anything up!


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C orrupt Block RecoveryC orrupt Block Recovery

(No Downtime) Without Prior(No Downtime) Without PriorRMAN Backups!RMAN Backups!


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Wh at Are Your Options To Handle Corruption?

DBMS_R E PAIR Full database recovery

Individual datafile recovery

create table as select ;drop table ; recreate from export.RMAN


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RMAN to Repair Corruption W ith out P rior RMAN Backups! W ith out D owntime! W ith out D ata Loss!

Will this work?What is your present backup method?

1. E xport- O nly2. Cold backup copies - noarchivelog3. Cold backup copies - archivelog

4. Hot backup mode copies5 . Consistent snap (crash-consistent) copies


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Non-RMAN Backup Analysis:1. E xport- O nly

Not possible to restore without downtime!Data loss is likely!Terrible choice for backup!

2. Cold backup copies noarchivelogNot possible to restore without downtime!

Data loss is likely!Awful choice of backup for a database with high uptime needs!

3. Cold backup copies arc h ivelogRMAN can save the day!Why are you backing up cold with high uptime requirements?

4. Hot backup mode copiesRMAN can save the day!

5. Consistent snap (cras h -consistent) copiesRMAN can save the day!


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Example:No corruption in database yet (run after RMAN validate procedure).


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(example)Hot backup mode copy Last good backup.


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S tep #1Note file# and block# of corrupt block(s).

O ptions: (after RMAN validate is run)

Select from v $backup_corruptionselect distinct c.file# " F ile#",c.block# "Starting Block#", c.blocks "Range"from v $backup_corruption c, v $backup_set swhere c.set_stamp = s.set_stamp

and c.set_count = s.set_countand s.start_time > to_date('&before_time', ' YYYYMMDDHH24MISS')

order by 1,2;

Alert log

Trace fileDBVdbv file= blocksize=


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(example) S elect


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(example) Alert log


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(example) Trace file


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(example) D BV


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S tep #2:E nsure that the last good backup of the corrupted file is visible.


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(example)Proof that no RMAN backups exist & attempt block recover.


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S tep #3:Catalog the backup of the corrupt file in the controlfile using the RMAN utility.


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(example)O nly thing in controlfile.


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S tep #4:Recover the corrupt block(s) using the RMAN utility.


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(example) D BV (after fix)


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(example)But record of corruption remains in view.


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P rosRMAN just saved you from instance downtimefor a corruption recovery, without a prior RMANbackup and without data loss!!

ConsIf your first corruption check identifies corruption,it will be difficult to find the last good, corruption-less backup. To be effective, regular corruptionchecks are highly recommended.If you wanted to make corruption sound like thebig deal that it is, you have just gone under theradar by maintaining uptime, so you will not getthe attention that you had hoped for


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CO NCL USI O NCO NCL USI O N

There Is No GoodThere Is No GoodReason For NotReason For Not

Using RMAN!Using RMAN!


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Q UESTI O NS?Q UESTI O NS?

C ontact Info:C ontact Info:Raj@Pal f oundation .ne t Raj@Pal f oundation .ne t

Documents

2007 RMOUG PAL Presentation