Backup Recovery Scenarios
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Describe various Backup and Recovery Scenarios SCOPE & APPLICATION A suppor! ana ys!s RELATED DOCU"ENTS Backup and Recovery #andBook$ In!ro !o Da!aServer Course "a!eria Backup and Recovery % an Overvie& Backup a' Consis!en! backups A consis!en! backup (eans !)a! a da!a *i es and con!ro *i es are consis!en! !o a poin! in !i(e+ I+e+ !)ey )ave !)e sa(e SCN+ T)is is !)e on y (e!)od o* backup &)en !)e da!abase is in NO Arc)ive o, (ode+ b' Inconsis!en! backups An Inconsis!en! backup is possib e on y &)en !)e da!abase is in Arc)ive o, (ode and proper Orac e a&are so*!&are is used+ "os! de*au ! backup so*!&are can no! backup open *i es+ Specia precau!ions need !o be used and !es!in, needs !o be done+ -ou (us! app y redo o,s !o !)e da!a *i es$ in order !o res!ore !)e da!abase !o a consis!en! s!a!e+ c' Da!abase Arc)ive (ode T)e da!abase can run in ei!)er Arc)ive o, (ode or noarc)ive o, (ode+ .)en you *irs! crea!e !)e da!abase$ you speci*y i* i! is !o be in Arc)ive o, (ode+ T)en in !)e ini!+ora *i e you se! !)e para(e!er o,/arc)ive/s!ar!0!rue so !)a! arc)ivin, &i s!ar! au!o(a!ica y on s!ar!up+ I* !)e da!abase )as no! been crea!ed &i!) Arc)ive o, (ode enab ed$ you can issue !)e co((and &)i s! !)e da!abase is (oun!ed$ no! open+ S1R"2R3 a !er da!abase Arc)ive o,4+ S1R"2R3 o, arc)ive s!ar! S1R"2R3 a !er da!abase open S1R"2R3 arc)ive o, is! T)is co((and &i s)o& you !)e o, (ode and i* au!o(a!ic arc)iva is se!+ d' Backup "e!)ods Essen!ia y$ !)ere are !&o backup (e!)ods$ )o! and co d$ a so kno&n as on ine and o** ine$ respec!ive y+ A co d backup is one !aken &)en !)e da!abase is s)u!do&n+ A )o! backup is on !aken &)en !)e da!abase is runnin,+ Co((ands *or a )o! backup5 6+ Svr(,r3a !er da!abase Arc)ive o, Svr(,r3 o, arc)ive s!ar! Svr(,r3 a !er da!abase open 7+ Svr(,r3 arc)ive o, is! 8 T)is &i s)o& &)a! !)e o des! on ine o, se9uence is+ As a precau!ion$ a &ays keep !)e a arc)ived o, *i es s!ar!in, *ro( !)e o des! on ine o, se9uence+ :+ Svr(,r3 A !er !ab espace !ab espace/na(e BE2IN BAC;UP <+=Usin, an OS co((and$ backup !)e da!a*i e>s' o* !)is !ab espace+ ?+ Svr(,r3 A !er !ab espace !ab espace/na(e END BAC;UP %%% repea! s!ep :$ <$ ? *or eac) !ab espace+ @+ Svr(,r3 arc)ive o, is!
%%%do !)is a,ain !o ob!ain !)e curren! o, se9uence+ -ou &i &an! !o (ake sure you )ave a copy o* !)is redo o, *i e$ so !o *orce an arc)ived o,$ issue A+ Svr(,r3 ALTER S-STE" S.ITC# LO2BILE C+ Backup a arc)ived o, *i es de!er(ined *ro( s!eps 7 and @+ Do no! backup !)e on ine redo o,s+ T)ese &i con!ain !)e end%o*%backup (arker and can cause corrup!ion i* use doin, recovery+ D+ Back up !)e con!ro *i e5 Svr(,r3 A !er da!abase backup con!ro *i e !o E*i ena(eF e' Incre(en!a backups T)ese are backups !)a! are !aken on b ocks !)a! )ave been (odi*ied since !)e as! backup+ T)ese are use*u as !)ey donF! !ake up as (uc) space and !i(e+ T)ere are !&o kinds o* incre(en!a backups Cu(u a!ive and Non cu(u a!ive+ Cu(u a!ive incre(en!a backups inc ude a b ocks !)a! &ere c)an,ed since !)e as! backup a! a o&er eve + T)is one reduces !)e &ork durin, res!ora!ion as on y one backup con!ains a !)e c)an,ed b ocks+ Noncu(u a!ive on y inc udes b ocks !)a! &ere c)an,ed since !)e previous backup a! !)e sa(e or o&er eve + Usin, r(an$ you issue !)e co((and Gbackup incre(en!a eve nH *' Suppor! scenarios .)en !)e da!abase cras)es$ you no& )ave a backup+ -ou res!ore !)e backup and !)en recover !)e da!abase+ A so$ donF! *or,e! !o !ake a backup o* !)e con!ro *i e &)enever !)ere is a sc)e(a c)an,e+ RECO1ERT)ere are severa kinds o* recovery you can per*or($ dependin, on !)e !ype o* *ai ure and !)e kind o* backup you )ave+ Essen!ia y$ i* you are no! runnin, in arc)ive o, (ode$ !)en you can on y recover !)e co d backup o* !)e da!abase and you &i ose any ne& da!a and c)an,es (ade since !)a! backup &as !aken+ I*$ )o&ever$ !)e da!abase is in Arc)ive o, (ode you &i be ab e !o res!ore !)e da!abase up !o !)e !i(e o* *ai ure+ T)ere are !)ree basic !ypes o* recovery5 6+ On ine B ock Recovery+ T)is is per*or(ed au!o(a!ica y by Orac e+>p(on' Occurs &)en a process dies &)i e c)an,in, a bu**er+ Orac e &i recons!ruc! !)e bu**er usin, !)e on ine redo o,s and &ri!es i! !o disk+ 7+ T)read Recovery+ T)is is a so per*or(ed au!o(a!ica y by Orac e+ Occurs &)en an ins!ance cras)es &)i e )avin, !)e da!abase open+ Orac e app ies a !)e redo c)an,es in !)e !)read !)a! occurred since !)e as! !i(e !)e !)read &as c)eckpoin!ed+ :+ "edia Recovery+ T)is is re9uired &)en a da!a *i e is res!ored *ro( backup+ T)e c)eckpoin! coun! in !)e da!a *i es )ere are no! e9ua !o !)e c)eck poin! coun! in !)e con!ro *i e+ T)is is a so re9uired &)en a *i e &as o** ined &i!)ou! c)eckpoin! and &)en usin, a backup con!ro *i e+ No& e!Fs eIp ain a i!! e abou! Redo vs Ro back+ Redo in*or(a!ion is recorded so !)a! a co((ands !)a! !ook p ace can be repea!ed durin, recovery+ Ro back in*or(a!ion is recorded so !)a! you can undo c)an,es (ade by !)e curren! !ransac!ion bu! &ere no! co((i!!ed+ T)e Redo Lo,s are used !o Ro Bor&ard !)e c)an,es (ade$ bo!) co((i!!ed and non% co((i!!ed c)an,es+ T)en *ro( !)e Ro back se,(en!s$ !)e undo in*or(a!ion is used !o ro back !)e unco((i!!ed c)an,es+ "edia Bai ure and Recovery in Noarc)ive o, "ode In !)is case$ your on y op!ion is !o res!ore a backup o* your Orac e *i es+ T)e *i es you need are a da!a*i es$ and con!ro *i es+
-ou on y need !o res!ore !)e pass&ord *i e or para(e!er *i es i* !)ey are os! or are corrup!ed+ "edia Bai ure and Recovery in Arc)ive o, "ode In !)is case$ !)ere are severa kinds o* recovery you can per*or($ dependin, on &)a! )as been os!+ T)e !)ree basic kinds o* recovery are5 6+ Recover da!abase % )ere you use !)e recover da!abase co((and and !)e da!abase (us! be c osed and (oun!ed+ Orac e &i recover a da!a*i es !)a! are on ine+ 7+ Recover !ab espace % use !)e recover !ab espace co((and+ T)e da!abase can be open bu! !)e !ab espace (us! be o** ine+ :+ Recover da!a*i e % use !)e recover da!a*i e co((and+ T)e da!abase can be open bu! !)e speci*ied da!a*i e (us! be o** ine+ No!e5 -ou (us! )ave a arc)ived o,s since !)e backup you res!ored *ro($ or e se you &i no! )ave a co(p e!e recovery+ a' Poin! in Ti(e recovery5 A !ypica scenario is !)a! you dropped a !ab e a! say noon$ and &an! !o recover i!+ -ou &i )ave !o res!ore !)e appropria!e da!a*i es and do a poin!%in%!i(e recovery !o a !i(e Jus! be*ore noon+ No!e5 you &i ose any !ransac!ions !)a! occurred a*!er noon+ A*!er you )ave recovered un!i noon$ you (us! open !)e da!abase &i!) rese! o,s+ T)is is necessary !o rese! !)e o, nu(bers$ &)ic) &i pro!ec! !)e da!abase *ro( )avin, !)e redo o,s !)a! &erenF! used be app ied+ T)e *our inco(p e!e recovery scenarios a &ork !)e sa(e5 Recover da!abase un!i !i(e E6DDD%67%K65675KK5KKF4 Recover da!abase un!i cance 4 >you !ype in cance !o s!op' Recover da!abase un!i c)an,e n4 Recover da!abase un!i cance usin, backup con!ro *i e4 No!e5 .)en per*or(in, an inco(p e!e recovery$ !)e da!a*i es (us! be on ine+ Do a se ec! na(e$ s!a!us *ro( vLda!a*i e !o *ind ou! i* !)ere are any *i es &)ic) are o** ine+ I* you &ere !o per*or( a recovery on a da!abase &)ic) )as !ab espaces o** ine$ and !)ey )ad no! been !aken o** ine in a nor(a s!a!e$ you &i ose !)e( &)en you issue !)e open rese! o,s co((and+ T)is is because !)e da!a *i e needs recovery *ro( a poin! be*ore !)e rese! o,s op!ion &as used+ b' Recovery &i!)ou! con!ro *i e I* you )ave os! !)e curren! con!ro *i e$ or !)e curren! con!ro *i e is inconsis!en! &i!) *i es !)a! you need !o recover$ you need !o recover ei!)er by usin, a backup con!ro *i e co((and or crea!e a ne& con!ro *i e+ -ou can a so recrea!e !)e con!ro *i e based on !)e curren! one usin, !)e Ebackup con!ro *i e !o !raceF co((and &)ic) &i crea!e a scrip! *or you !o run !o crea!e a ne& one+ Recover da!abase usin, backup con!ro *i e co((and (us! be used &)en usin, a con!ro *i e o!)er !)a! !)e curren!+ T)e da!abase (us! !)en be opened &i!) rese! o,s op!ion+ c' Recovery o* (issin, da!a*i e &i!) ro back se,(en! T)e !ricky par! )ere is i* you are per*or(in, on ine recovery+ O!)er&ise you can Jus! use !)e recover da!a*i e co((and+ No&$ i* you are per*or(in, an on ine recovery$ you (us! *irs! ensure !)a! in !)e ini!+ora *i e$ you re(ove !)e para(e!er ro back/se,(en!s+ O!)er&ise$ orac e &i &an! !o use !)ose ro back se,(en!s &)en openin, !)e da!abase$ bu! canF! *ind !)e( and &on! open+ Un!i you recover !)e da!a*i es !)a! con!ain !)e ro back se,(en!s$ you need !o crea!e so(e !e(porary ro back se,(en!s in order *or ne& !ransac!ions !o &ork+ Even i* o!)er ro back se,(en!s are ok$ !)ey &i )ave !o be !aken o** ine+ So$ a !)e ro back se,(en!s !)a! be on, !o !)e da!a*i e need !o be recovered+ I* a !)e da!a*i es be on,in, !o !)e !ab espace ro back/da!a &ere os!$ you can no& issue a recover !ab espace ro back/da!a+ NeI! brin, !)e !ab espace on ine and c)eck !)e s!a!us o* !)e ro back se,(en!s by doin, a se ec! se,(en!/na(e$ s!a!us *ro( dba/ro back/se,s4 -ou &i see !)e is! o* ro back se,(en!s !)a! are in s!a!us Need Recovery+
Si(p y issue a !er ro back se,(en! on ine co((and !o co(p e!e+ DonF! *or,e! !o rese! !)e ro back/se,(en!s para(e!er in !)e ini!+ora+ d' Recovery o* (issin, da!a*i e &i!)ou! ro back se,(en! T)ere are !)ree &ays !o recover in !)is scenario$ as (en!ioned above+ 6+ recover da!abase 7+ recover da!a*i e Ec5Moran!Mda!abaseMusr6orc +oraF :+ recover !ab espace user/da!a e' Recovery &i!) (issin, on ine redo o,s "issin, on ine redo o,s (eans !)a! so(e)o& you )ave os! your redo o,s be*ore !)ey )ad a c)ance !o arc)ived+ T)is (eans !)a! cras) recovery canno! be per*or(ed$ so (edia recovery is re9uired ins!ead+ A da!a*i es &i need !o beres!ored and ro ed *or&arded un!i !)e as! avai ab e arc)ived o, *i e is app ied+ T)is is !)us an inco(p e!e recovery$ and as suc)$ !)e recover da!abase co((and is necessary+ >i+e+ you canno! do a da!a*i e or !ab espace recovery'+ As a &ays$ &)en an inco(p e!e recovery is per*or(ed$ you (us! open !)e da!abase &i!) rese! o,s+ No!e5 !)e bes! &ay !o avoid !)is kind o* a oss$ is !o (irror your on ine o, *i es+ *' Recovery &i!) (issin, arc)ived redo o,s I* your arc)ives are (issin,$ !)e on y &ay !o recover !)e da!abase is !o res!ore *ro( your a!es! backup+ -ou &i )ave os! any unco((i!!ed !ransac!ions &)ic) &ere recorded in !)e arc)ived redo o,s+ A,ain$ !)is is &)y Orac e s!ron, y su,,es!s (irrorin, your on ine redo o,s and dup ica!in, copies o* !)e arc)ives+ ,' Recovery &i!) rese! o,s op!ion Rese! o, op!ion s)ou d be !)e as! resor!$ )o&ever$ as &e )ave seen *ro( above$ i! (ay be re9uired due !o inco(p e!e recoveries+ >recover usin, a backup con!ro *i e$ or a poin! in !i(e recovery'+ I! is i(pera!ive !)a! you backup up !)e da!abase i((edia!e y a*!er you )ave opened !)e da!abase &i!) rese! o,s+ T)e reason is !)a! orac e upda!es !)e con!ro *i e and rese!s o, nu(bers$ and you &i no! be ab e !o recover *ro( !)e o d o,s+ T)e neI! concern &i be i* !)e da!abase cras)es a*!er you )ave opened !)e da!abase &i!) rese! o,s$ bu! )ave no! )ad !i(e !o backup !)e da!abase+ #o& !o recoverN S)u! do&n !)e da!abase Backup a !)e da!a*i es and !)e con!ro *i e S!ar!up (oun! A !er da!abase open rese! o,s T)is &i &ork$ because you )ave a copy o* a con!ro *i e a*!er !)e rese! o,s poin!+ "edia *ai ure be*ore a backup a*!er rese! o,s+ I* a (edia *ai ure s)ou d occur be*ore a backup &as (ade a*!er you opened !)e da!abase usin, rese! o,s$ you &i (os! ike y ose da!a+ T)e reason is because res!orin, a os! da!a*i e *ro( a backup prior !o !)e rese! o,s &i ,ive an error !)a! !)e *i e is *ro( a poin! in !i(e ear ier$ and you donF! )ave i!s backup o, any(ore+ )' Recovery &i!) corrup!edO(issin, ro back se,(en!s+ I* a ro back se,(en! is (issin, or corrup!ed$ you &i no! be ab e !o open !)e da!abase+ T)e *irs! s!ep is !o *ind ou! &)a! obJec! is causin, !)e ro back !o appear corrup!ed+ I* &e can de!er(ine !)a!$ &e can drop !)a! obJec!+ I* &e canF! &e &i need !o o, an iTar !o en,a,e suppor!+ So$ )o& do &e *ind ou! i* i!Fs ac!ua y a bad obJec!N 6+ "ake sure !)a! a !ab espaces are on ine and a da!a*i es are on ine+ T)is can be c)ecked !)rou,) vLda!a*i e$ under !)e s!a!us co u(n+
Bor !ab espaces associa!ed &i!) !)e da!a*i es$ ook in dba/!ab espaces+ I* !)is doesnF! s)o& us any!)in,$ i+e+$ a are on ine$ !)en 7+ Pu! !)e *o o&in, in !)e ini!+ora5 even! 0 G6KK6? !race na(e con!eI! *orever$ eve 6KH T)is even! &i ,enera!e a !race *i e !)a! &i revea in*or(a!ion abou! !)e !ransac!ion Orac e is !ryin, !o ro back and (os! i(por!an! y$ &)a! obJec! Orac e is !ryin, !o app y !)e undo !o+ S!op and s!ar! !)e da!abase+ :+ C)eck in !)e direc!ory !)a! is speci*ied by !)e user/du(p/des! para(e!er >in !)e ini!+ora or s)o& para(e!er co((and' *or a !race *i e !)a! &as ,enera!ed a! s!ar!up !i(e+ <+ In !)e !race *i e$ !)ere s)ou d be a (essa,e si(i ar !o5 error recovery !I>P$P' obJec! P+ TQ>P$P' re*ers !o !ransac!ion in*or(a!ion+ T)e obJec! P is !)e sa(e as !)e obJec!/id in sys+dba/obJec!s+ ?+ Use !)e *o o&in, 9uery !o *ind ou! &)a! obJec! Orac e is !ryin, !o per*or( recovery on+ se ec! o&ner$ obJec!/na(e$ obJec!/!ype$ s!a!us *ro( dba/obJec!s &)ere obJec!/id 0 RobJec! P34 @+ Drop !)e o**endin, obJec! so !)e undo can be re eased+ An eIpor! or re yin, on a backup (ay be necessary !o res!ore !)e obJec! a*!er !)e corrup!ed ro back se,(en! ,oes a&ay+ A+ A*!er droppin, !)e obJec!$ pu! !)e ro back se,(en! back in !)e ini!+ora para(e!er ro back/se,(en!s$ re(ove !)e even!$ and s)u!do&n and s!ar!up !)e da!abase+ In (os! cases$ !)e above s!eps &i reso ve !)e prob e(a!ic ro back se,(en!+ I* !)is s!i does no! reso ve !)e prob e($ i! (ay be ike y !)a! !)e corrup!ion is in !)e ac!ua ro back se,(en!+ I* in *ac! !)e ro back se,(en! i!se * is corrup!ed$ &e s)ou d see i* &e can res!ore *ro( a backup+ #o&ever$ !)a! isnF! a &ays possib e$ !)ere (ay no! be a recen! backup e!c+ In !)is case$ &e )ave !o *orce !)e da!abase open &i!) !)e unsuppor!ed$ )idden para(e!ers$ you &i need !o o, an iTar !o en,a,e suppor!+ P ease no!e$ !)a! !)is is po!en!ia y dan,erousS .)en !)ese are used$ !ransac!ion !ab es are no! read on openin, o* !)e da!abase Because o* !)is$ !)e !ypica sa*e,uards associa!ed &i!) !)e ro back se,(en! are disab ed+ T)eir s!a!us is Eo** ineF in dba/ro back/se,s+ Conse9uen! y$ !)ere is no c)eck *or ac!ive !ransac!ions be*ore droppin, !)e ro back se,(en!+ I* you drop a ro back se,(en! &)ic) con!ains ac!ive !ransac!ions !)en you &i )ave o,ica corrup!ion+ Possib y !)is corrup!ion &i be in !)e da!a dic!ionary+ I* !)e ro back se,(en! da!a*i e is p)ysica y (issin,$ )as been o** ined dropped$ or !)e ro back se,(en! )eader i!se * is corrup!$ !)ere is no &ay !o du(p !)e !ransac!ion !ab e !o c)eck *or ac!ive !ransac!ions+ So !)e on y !)in, !o do is ,e! !)e da!abase open$ eIpor! and rebui d+ Lo, an iTar !o en,a,e suppor! !o )e p &i!) !)is process+ I* you canno! ,e! !)e da!abase open$ !)ere is no o!)er a !erna!ive !)an res!orin, *ro( a backup+ i' Recovery &i!) Sys!e( C ock c)an,e+ -ou can end up &i!) dup ica!e !i(es!a(ps in !)e da!a*i es &)en a sys!e( c ock c)an,es+ A so u!ion )ere is !o recover !)e da!abase un!i !i(e Eyyyy%((%dd5KK5KK5KKF$ and se! !)e !i(e !o be a!er !)an !)e &)en !)e prob e( occurred+ T)a! &ay i! &i ro *or&ard !)rou,) !)e records !)a! &ere ac!ua y per*or(ed a!er$ bu! )ave an ear ier !i(e s!a(p due !o !)e sys!e( c ock c)an,e+ Per*or(in, a co(p e!e recovery is op!i(a $ as a !ransac!ions &i be app ied+ J' Recovery &i!) (issin, Sys!e( !ab espace+
T)e on y op!ion is !o res!ore *ro( a backup+ k' "edia Recovery o* o** ine !ab espace .)en a !ab espace is o** ine$ you canno! recover da!a*i es be on,in, !o !)is !ab espace usin, recover da!abase co((and+ T)e reason is because a recover da!abase co((and &i on y recover on ine da!a*i es+ Since !)e !ab espace is o** ine$ i! !)inks !)e da!a*i es are o** ine as &e $ so even i* you recover da!abase and ro *or&ard$ !)e da!a*i es in !)is !ab espace &i no! be !ouc)ed+ Ins!ead$ you need !o per*or( a recover !ab espace co((and+ A !erna!ive y$ you cou d res!ored !)e da!a*i es *ro( a co d backup$ (oun! !)e da!abase and se ec! *ro( !)e vLda!a*i e vie& !o see i* any o* !)e da!a*i es are o** ine+ I* !)ey are$ brin, !)e( on ine$ and !)en you can per*or( a recover da!abase co((and+ ' Recovery o* Read%On y !ab espaces I* you )ave a curren! con!ro *i e$ !)en recovery o* read on y !ab espaces is no di**eren! !)an recoverin, read%&ri!e *i es+ T)e issues &i!) read%on y !ab espaces arise i* you )ave !o use a backup con!ro *i e+ I* !)e !ab espace is in read%on y (ode$ and )asnF! c)an,ed !o read%&ri!e since !)e as! backup$ !)en you &i be ab e !o (edia recovery usin, a backup con!ro *i e by !akin, !)e !ab espace o** ine+ T)e reason )ere is !)a! &)en you are usin, !)e backup con!ro *i e$ you (us! open !)e da!abase &i!) rese! o,s+ And &e kno& !)a! Orac e &on! e! you read *i es *ro( be*ore a rese! o,s &as done+ #o&ever$ !)ere is an eIcep!ion &i!) read%on y !ab espaces+ -ou &i be ab e !o !ake !)e da!a*i es on ine a*!er you )ave opened !)e da!abase+ .)en you )ave !ab espaces !)a! s&i!c) (odes and you donF! )ave a curren! con!ro *i e$ you s)ou d use a backup con!ro *i e !)a! reco,niTes !)e !ab espace in read%&ri!e (ode+ I* you donF! )ave a backup con!ro *i e$ you can crea!e a ne& one usin, !)e crea!e con!ro *i e co((and+ Basica y$ !)e poin! )ere is !)a! you s)ou d !ake a backup o* !)e con!ro *i e every !i(e you s&i!c) a !ab espaces (od+
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Describe various Backup and Recovery Scenarios SCOPE & APPLICATION A suppor! ana ys!s RELATED DOCU"ENTS Backup and Recovery #andBook$ In!ro !o Da!aServer Course "a!eria Backup and Recovery % an Overvie& Backup a' Consis!en! backups A consis!en! backup (eans !)a! a da!a *i es and con!ro *i es are consis!en! !o a poin! in !i(e+ I+e+ !)ey )ave !)e sa(e SCN+ T)is is !)e on y (e!)od o* backup &)en !)e da!abase is in NO Arc)ive o, (ode+ b' Inconsis!en! backups An Inconsis!en! backup is possib e on y &)en !)e da!abase is in Arc)ive o, (ode and proper Orac e a&are so*!&are is used+ "os! de*au ! backup so*!&are can no! backup open *i es+ Specia precau!ions need !o be used and !es!in, needs !o be done+ -ou (us! app y redo o,s !o !)e da!a *i es$ in order !o res!ore !)e da!abase !o a consis!en! s!a!e+ c' Da!abase Arc)ive (ode T)e da!abase can run in ei!)er Arc)ive o, (ode or noarc)ive o, (ode+ .)en you *irs! crea!e !)e da!abase$ you speci*y i* i! is !o be in Arc)ive o, (ode+ T)en in !)e ini!+ora *i e you se! !)e para(e!er o,/arc)ive/s!ar!0!rue so !)a! arc)ivin, &i s!ar! au!o(a!ica y on s!ar!up+ I* !)e da!abase )as no! been crea!ed &i!) Arc)ive o, (ode enab ed$ you can issue !)e co((and &)i s! !)e da!abase is (oun!ed$ no! open+ S1R"2R3 a !er da!abase Arc)ive o,4+ S1R"2R3 o, arc)ive s!ar! S1R"2R3 a !er da!abase open S1R"2R3 arc)ive o, is! T)is co((and &i s)o& you !)e o, (ode and i* au!o(a!ic arc)iva is se!+ d' Backup "e!)ods Essen!ia y$ !)ere are !&o backup (e!)ods$ )o! and co d$ a so kno&n as on ine and o** ine$ respec!ive y+ A co d backup is one !aken &)en !)e da!abase is s)u!do&n+ A )o! backup is on !aken &)en !)e da!abase is runnin,+ Co((ands *or a )o! backup5 6+ Svr(,r3a !er da!abase Arc)ive o, Svr(,r3 o, arc)ive s!ar! Svr(,r3 a !er da!abase open 7+ Svr(,r3 arc)ive o, is! 8 T)is &i s)o& &)a! !)e o des! on ine o, se9uence is+ As a precau!ion$ a &ays keep !)e a arc)ived o, *i es s!ar!in, *ro( !)e o des! on ine o, se9uence+ :+ Svr(,r3 A !er !ab espace !ab espace/na(e BE2IN BAC;UP <+=Usin, an OS co((and$ backup !)e da!a*i e>s' o* !)is !ab espace+ ?+ Svr(,r3 A !er !ab espace !ab espace/na(e END BAC;UP %%% repea! s!ep :$ <$ ? *or eac) !ab espace+ @+ Svr(,r3 arc)ive o, is!
%%%do !)is a,ain !o ob!ain !)e curren! o, se9uence+ -ou &i &an! !o (ake sure you )ave a copy o* !)is redo o, *i e$ so !o *orce an arc)ived o,$ issue A+ Svr(,r3 ALTER S-STE" S.ITC# LO2BILE C+ Backup a arc)ived o, *i es de!er(ined *ro( s!eps 7 and @+ Do no! backup !)e on ine redo o,s+ T)ese &i con!ain !)e end%o*%backup (arker and can cause corrup!ion i* use doin, recovery+ D+ Back up !)e con!ro *i e5 Svr(,r3 A !er da!abase backup con!ro *i e !o E*i ena(eF e' Incre(en!a backups T)ese are backups !)a! are !aken on b ocks !)a! )ave been (odi*ied since !)e as! backup+ T)ese are use*u as !)ey donF! !ake up as (uc) space and !i(e+ T)ere are !&o kinds o* incre(en!a backups Cu(u a!ive and Non cu(u a!ive+ Cu(u a!ive incre(en!a backups inc ude a b ocks !)a! &ere c)an,ed since !)e as! backup a! a o&er eve + T)is one reduces !)e &ork durin, res!ora!ion as on y one backup con!ains a !)e c)an,ed b ocks+ Noncu(u a!ive on y inc udes b ocks !)a! &ere c)an,ed since !)e previous backup a! !)e sa(e or o&er eve + Usin, r(an$ you issue !)e co((and Gbackup incre(en!a eve nH *' Suppor! scenarios .)en !)e da!abase cras)es$ you no& )ave a backup+ -ou res!ore !)e backup and !)en recover !)e da!abase+ A so$ donF! *or,e! !o !ake a backup o* !)e con!ro *i e &)enever !)ere is a sc)e(a c)an,e+ RECO1ERT)ere are severa kinds o* recovery you can per*or($ dependin, on !)e !ype o* *ai ure and !)e kind o* backup you )ave+ Essen!ia y$ i* you are no! runnin, in arc)ive o, (ode$ !)en you can on y recover !)e co d backup o* !)e da!abase and you &i ose any ne& da!a and c)an,es (ade since !)a! backup &as !aken+ I*$ )o&ever$ !)e da!abase is in Arc)ive o, (ode you &i be ab e !o res!ore !)e da!abase up !o !)e !i(e o* *ai ure+ T)ere are !)ree basic !ypes o* recovery5 6+ On ine B ock Recovery+ T)is is per*or(ed au!o(a!ica y by Orac e+>p(on' Occurs &)en a process dies &)i e c)an,in, a bu**er+ Orac e &i recons!ruc! !)e bu**er usin, !)e on ine redo o,s and &ri!es i! !o disk+ 7+ T)read Recovery+ T)is is a so per*or(ed au!o(a!ica y by Orac e+ Occurs &)en an ins!ance cras)es &)i e )avin, !)e da!abase open+ Orac e app ies a !)e redo c)an,es in !)e !)read !)a! occurred since !)e as! !i(e !)e !)read &as c)eckpoin!ed+ :+ "edia Recovery+ T)is is re9uired &)en a da!a *i e is res!ored *ro( backup+ T)e c)eckpoin! coun! in !)e da!a *i es )ere are no! e9ua !o !)e c)eck poin! coun! in !)e con!ro *i e+ T)is is a so re9uired &)en a *i e &as o** ined &i!)ou! c)eckpoin! and &)en usin, a backup con!ro *i e+ No& e!Fs eIp ain a i!! e abou! Redo vs Ro back+ Redo in*or(a!ion is recorded so !)a! a co((ands !)a! !ook p ace can be repea!ed durin, recovery+ Ro back in*or(a!ion is recorded so !)a! you can undo c)an,es (ade by !)e curren! !ransac!ion bu! &ere no! co((i!!ed+ T)e Redo Lo,s are used !o Ro Bor&ard !)e c)an,es (ade$ bo!) co((i!!ed and non% co((i!!ed c)an,es+ T)en *ro( !)e Ro back se,(en!s$ !)e undo in*or(a!ion is used !o ro back !)e unco((i!!ed c)an,es+ "edia Bai ure and Recovery in Noarc)ive o, "ode In !)is case$ your on y op!ion is !o res!ore a backup o* your Orac e *i es+ T)e *i es you need are a da!a*i es$ and con!ro *i es+
-ou on y need !o res!ore !)e pass&ord *i e or para(e!er *i es i* !)ey are os! or are corrup!ed+ "edia Bai ure and Recovery in Arc)ive o, "ode In !)is case$ !)ere are severa kinds o* recovery you can per*or($ dependin, on &)a! )as been os!+ T)e !)ree basic kinds o* recovery are5 6+ Recover da!abase % )ere you use !)e recover da!abase co((and and !)e da!abase (us! be c osed and (oun!ed+ Orac e &i recover a da!a*i es !)a! are on ine+ 7+ Recover !ab espace % use !)e recover !ab espace co((and+ T)e da!abase can be open bu! !)e !ab espace (us! be o** ine+ :+ Recover da!a*i e % use !)e recover da!a*i e co((and+ T)e da!abase can be open bu! !)e speci*ied da!a*i e (us! be o** ine+ No!e5 -ou (us! )ave a arc)ived o,s since !)e backup you res!ored *ro($ or e se you &i no! )ave a co(p e!e recovery+ a' Poin! in Ti(e recovery5 A !ypica scenario is !)a! you dropped a !ab e a! say noon$ and &an! !o recover i!+ -ou &i )ave !o res!ore !)e appropria!e da!a*i es and do a poin!%in%!i(e recovery !o a !i(e Jus! be*ore noon+ No!e5 you &i ose any !ransac!ions !)a! occurred a*!er noon+ A*!er you )ave recovered un!i noon$ you (us! open !)e da!abase &i!) rese! o,s+ T)is is necessary !o rese! !)e o, nu(bers$ &)ic) &i pro!ec! !)e da!abase *ro( )avin, !)e redo o,s !)a! &erenF! used be app ied+ T)e *our inco(p e!e recovery scenarios a &ork !)e sa(e5 Recover da!abase un!i !i(e E6DDD%67%K65675KK5KKF4 Recover da!abase un!i cance 4 >you !ype in cance !o s!op' Recover da!abase un!i c)an,e n4 Recover da!abase un!i cance usin, backup con!ro *i e4 No!e5 .)en per*or(in, an inco(p e!e recovery$ !)e da!a*i es (us! be on ine+ Do a se ec! na(e$ s!a!us *ro( vLda!a*i e !o *ind ou! i* !)ere are any *i es &)ic) are o** ine+ I* you &ere !o per*or( a recovery on a da!abase &)ic) )as !ab espaces o** ine$ and !)ey )ad no! been !aken o** ine in a nor(a s!a!e$ you &i ose !)e( &)en you issue !)e open rese! o,s co((and+ T)is is because !)e da!a *i e needs recovery *ro( a poin! be*ore !)e rese! o,s op!ion &as used+ b' Recovery &i!)ou! con!ro *i e I* you )ave os! !)e curren! con!ro *i e$ or !)e curren! con!ro *i e is inconsis!en! &i!) *i es !)a! you need !o recover$ you need !o recover ei!)er by usin, a backup con!ro *i e co((and or crea!e a ne& con!ro *i e+ -ou can a so recrea!e !)e con!ro *i e based on !)e curren! one usin, !)e Ebackup con!ro *i e !o !raceF co((and &)ic) &i crea!e a scrip! *or you !o run !o crea!e a ne& one+ Recover da!abase usin, backup con!ro *i e co((and (us! be used &)en usin, a con!ro *i e o!)er !)a! !)e curren!+ T)e da!abase (us! !)en be opened &i!) rese! o,s op!ion+ c' Recovery o* (issin, da!a*i e &i!) ro back se,(en! T)e !ricky par! )ere is i* you are per*or(in, on ine recovery+ O!)er&ise you can Jus! use !)e recover da!a*i e co((and+ No&$ i* you are per*or(in, an on ine recovery$ you (us! *irs! ensure !)a! in !)e ini!+ora *i e$ you re(ove !)e para(e!er ro back/se,(en!s+ O!)er&ise$ orac e &i &an! !o use !)ose ro back se,(en!s &)en openin, !)e da!abase$ bu! canF! *ind !)e( and &on! open+ Un!i you recover !)e da!a*i es !)a! con!ain !)e ro back se,(en!s$ you need !o crea!e so(e !e(porary ro back se,(en!s in order *or ne& !ransac!ions !o &ork+ Even i* o!)er ro back se,(en!s are ok$ !)ey &i )ave !o be !aken o** ine+ So$ a !)e ro back se,(en!s !)a! be on, !o !)e da!a*i e need !o be recovered+ I* a !)e da!a*i es be on,in, !o !)e !ab espace ro back/da!a &ere os!$ you can no& issue a recover !ab espace ro back/da!a+ NeI! brin, !)e !ab espace on ine and c)eck !)e s!a!us o* !)e ro back se,(en!s by doin, a se ec! se,(en!/na(e$ s!a!us *ro( dba/ro back/se,s4 -ou &i see !)e is! o* ro back se,(en!s !)a! are in s!a!us Need Recovery+
Si(p y issue a !er ro back se,(en! on ine co((and !o co(p e!e+ DonF! *or,e! !o rese! !)e ro back/se,(en!s para(e!er in !)e ini!+ora+ d' Recovery o* (issin, da!a*i e &i!)ou! ro back se,(en! T)ere are !)ree &ays !o recover in !)is scenario$ as (en!ioned above+ 6+ recover da!abase 7+ recover da!a*i e Ec5Moran!Mda!abaseMusr6orc +oraF :+ recover !ab espace user/da!a e' Recovery &i!) (issin, on ine redo o,s "issin, on ine redo o,s (eans !)a! so(e)o& you )ave os! your redo o,s be*ore !)ey )ad a c)ance !o arc)ived+ T)is (eans !)a! cras) recovery canno! be per*or(ed$ so (edia recovery is re9uired ins!ead+ A da!a*i es &i need !o beres!ored and ro ed *or&arded un!i !)e as! avai ab e arc)ived o, *i e is app ied+ T)is is !)us an inco(p e!e recovery$ and as suc)$ !)e recover da!abase co((and is necessary+ >i+e+ you canno! do a da!a*i e or !ab espace recovery'+ As a &ays$ &)en an inco(p e!e recovery is per*or(ed$ you (us! open !)e da!abase &i!) rese! o,s+ No!e5 !)e bes! &ay !o avoid !)is kind o* a oss$ is !o (irror your on ine o, *i es+ *' Recovery &i!) (issin, arc)ived redo o,s I* your arc)ives are (issin,$ !)e on y &ay !o recover !)e da!abase is !o res!ore *ro( your a!es! backup+ -ou &i )ave os! any unco((i!!ed !ransac!ions &)ic) &ere recorded in !)e arc)ived redo o,s+ A,ain$ !)is is &)y Orac e s!ron, y su,,es!s (irrorin, your on ine redo o,s and dup ica!in, copies o* !)e arc)ives+ ,' Recovery &i!) rese! o,s op!ion Rese! o, op!ion s)ou d be !)e as! resor!$ )o&ever$ as &e )ave seen *ro( above$ i! (ay be re9uired due !o inco(p e!e recoveries+ >recover usin, a backup con!ro *i e$ or a poin! in !i(e recovery'+ I! is i(pera!ive !)a! you backup up !)e da!abase i((edia!e y a*!er you )ave opened !)e da!abase &i!) rese! o,s+ T)e reason is !)a! orac e upda!es !)e con!ro *i e and rese!s o, nu(bers$ and you &i no! be ab e !o recover *ro( !)e o d o,s+ T)e neI! concern &i be i* !)e da!abase cras)es a*!er you )ave opened !)e da!abase &i!) rese! o,s$ bu! )ave no! )ad !i(e !o backup !)e da!abase+ #o& !o recoverN S)u! do&n !)e da!abase Backup a !)e da!a*i es and !)e con!ro *i e S!ar!up (oun! A !er da!abase open rese! o,s T)is &i &ork$ because you )ave a copy o* a con!ro *i e a*!er !)e rese! o,s poin!+ "edia *ai ure be*ore a backup a*!er rese! o,s+ I* a (edia *ai ure s)ou d occur be*ore a backup &as (ade a*!er you opened !)e da!abase usin, rese! o,s$ you &i (os! ike y ose da!a+ T)e reason is because res!orin, a os! da!a*i e *ro( a backup prior !o !)e rese! o,s &i ,ive an error !)a! !)e *i e is *ro( a poin! in !i(e ear ier$ and you donF! )ave i!s backup o, any(ore+ )' Recovery &i!) corrup!edO(issin, ro back se,(en!s+ I* a ro back se,(en! is (issin, or corrup!ed$ you &i no! be ab e !o open !)e da!abase+ T)e *irs! s!ep is !o *ind ou! &)a! obJec! is causin, !)e ro back !o appear corrup!ed+ I* &e can de!er(ine !)a!$ &e can drop !)a! obJec!+ I* &e canF! &e &i need !o o, an iTar !o en,a,e suppor!+ So$ )o& do &e *ind ou! i* i!Fs ac!ua y a bad obJec!N 6+ "ake sure !)a! a !ab espaces are on ine and a da!a*i es are on ine+ T)is can be c)ecked !)rou,) vLda!a*i e$ under !)e s!a!us co u(n+
Bor !ab espaces associa!ed &i!) !)e da!a*i es$ ook in dba/!ab espaces+ I* !)is doesnF! s)o& us any!)in,$ i+e+$ a are on ine$ !)en 7+ Pu! !)e *o o&in, in !)e ini!+ora5 even! 0 G6KK6? !race na(e con!eI! *orever$ eve 6KH T)is even! &i ,enera!e a !race *i e !)a! &i revea in*or(a!ion abou! !)e !ransac!ion Orac e is !ryin, !o ro back and (os! i(por!an! y$ &)a! obJec! Orac e is !ryin, !o app y !)e undo !o+ S!op and s!ar! !)e da!abase+ :+ C)eck in !)e direc!ory !)a! is speci*ied by !)e user/du(p/des! para(e!er >in !)e ini!+ora or s)o& para(e!er co((and' *or a !race *i e !)a! &as ,enera!ed a! s!ar!up !i(e+ <+ In !)e !race *i e$ !)ere s)ou d be a (essa,e si(i ar !o5 error recovery !I>P$P' obJec! P+ TQ>P$P' re*ers !o !ransac!ion in*or(a!ion+ T)e obJec! P is !)e sa(e as !)e obJec!/id in sys+dba/obJec!s+ ?+ Use !)e *o o&in, 9uery !o *ind ou! &)a! obJec! Orac e is !ryin, !o per*or( recovery on+ se ec! o&ner$ obJec!/na(e$ obJec!/!ype$ s!a!us *ro( dba/obJec!s &)ere obJec!/id 0 RobJec! P34 @+ Drop !)e o**endin, obJec! so !)e undo can be re eased+ An eIpor! or re yin, on a backup (ay be necessary !o res!ore !)e obJec! a*!er !)e corrup!ed ro back se,(en! ,oes a&ay+ A+ A*!er droppin, !)e obJec!$ pu! !)e ro back se,(en! back in !)e ini!+ora para(e!er ro back/se,(en!s$ re(ove !)e even!$ and s)u!do&n and s!ar!up !)e da!abase+ In (os! cases$ !)e above s!eps &i reso ve !)e prob e(a!ic ro back se,(en!+ I* !)is s!i does no! reso ve !)e prob e($ i! (ay be ike y !)a! !)e corrup!ion is in !)e ac!ua ro back se,(en!+ I* in *ac! !)e ro back se,(en! i!se * is corrup!ed$ &e s)ou d see i* &e can res!ore *ro( a backup+ #o&ever$ !)a! isnF! a &ays possib e$ !)ere (ay no! be a recen! backup e!c+ In !)is case$ &e )ave !o *orce !)e da!abase open &i!) !)e unsuppor!ed$ )idden para(e!ers$ you &i need !o o, an iTar !o en,a,e suppor!+ P ease no!e$ !)a! !)is is po!en!ia y dan,erousS .)en !)ese are used$ !ransac!ion !ab es are no! read on openin, o* !)e da!abase Because o* !)is$ !)e !ypica sa*e,uards associa!ed &i!) !)e ro back se,(en! are disab ed+ T)eir s!a!us is Eo** ineF in dba/ro back/se,s+ Conse9uen! y$ !)ere is no c)eck *or ac!ive !ransac!ions be*ore droppin, !)e ro back se,(en!+ I* you drop a ro back se,(en! &)ic) con!ains ac!ive !ransac!ions !)en you &i )ave o,ica corrup!ion+ Possib y !)is corrup!ion &i be in !)e da!a dic!ionary+ I* !)e ro back se,(en! da!a*i e is p)ysica y (issin,$ )as been o** ined dropped$ or !)e ro back se,(en! )eader i!se * is corrup!$ !)ere is no &ay !o du(p !)e !ransac!ion !ab e !o c)eck *or ac!ive !ransac!ions+ So !)e on y !)in, !o do is ,e! !)e da!abase open$ eIpor! and rebui d+ Lo, an iTar !o en,a,e suppor! !o )e p &i!) !)is process+ I* you canno! ,e! !)e da!abase open$ !)ere is no o!)er a !erna!ive !)an res!orin, *ro( a backup+ i' Recovery &i!) Sys!e( C ock c)an,e+ -ou can end up &i!) dup ica!e !i(es!a(ps in !)e da!a*i es &)en a sys!e( c ock c)an,es+ A so u!ion )ere is !o recover !)e da!abase un!i !i(e Eyyyy%((%dd5KK5KK5KKF$ and se! !)e !i(e !o be a!er !)an !)e &)en !)e prob e( occurred+ T)a! &ay i! &i ro *or&ard !)rou,) !)e records !)a! &ere ac!ua y per*or(ed a!er$ bu! )ave an ear ier !i(e s!a(p due !o !)e sys!e( c ock c)an,e+ Per*or(in, a co(p e!e recovery is op!i(a $ as a !ransac!ions &i be app ied+ J' Recovery &i!) (issin, Sys!e( !ab espace+
T)e on y op!ion is !o res!ore *ro( a backup+ k' "edia Recovery o* o** ine !ab espace .)en a !ab espace is o** ine$ you canno! recover da!a*i es be on,in, !o !)is !ab espace usin, recover da!abase co((and+ T)e reason is because a recover da!abase co((and &i on y recover on ine da!a*i es+ Since !)e !ab espace is o** ine$ i! !)inks !)e da!a*i es are o** ine as &e $ so even i* you recover da!abase and ro *or&ard$ !)e da!a*i es in !)is !ab espace &i no! be !ouc)ed+ Ins!ead$ you need !o per*or( a recover !ab espace co((and+ A !erna!ive y$ you cou d res!ored !)e da!a*i es *ro( a co d backup$ (oun! !)e da!abase and se ec! *ro( !)e vLda!a*i e vie& !o see i* any o* !)e da!a*i es are o** ine+ I* !)ey are$ brin, !)e( on ine$ and !)en you can per*or( a recover da!abase co((and+ ' Recovery o* Read%On y !ab espaces I* you )ave a curren! con!ro *i e$ !)en recovery o* read on y !ab espaces is no di**eren! !)an recoverin, read%&ri!e *i es+ T)e issues &i!) read%on y !ab espaces arise i* you )ave !o use a backup con!ro *i e+ I* !)e !ab espace is in read%on y (ode$ and )asnF! c)an,ed !o read%&ri!e since !)e as! backup$ !)en you &i be ab e !o (edia recovery usin, a backup con!ro *i e by !akin, !)e !ab espace o** ine+ T)e reason )ere is !)a! &)en you are usin, !)e backup con!ro *i e$ you (us! open !)e da!abase &i!) rese! o,s+ And &e kno& !)a! Orac e &on! e! you read *i es *ro( be*ore a rese! o,s &as done+ #o&ever$ !)ere is an eIcep!ion &i!) read%on y !ab espaces+ -ou &i be ab e !o !ake !)e da!a*i es on ine a*!er you )ave opened !)e da!abase+ .)en you )ave !ab espaces !)a! s&i!c) (odes and you donF! )ave a curren! con!ro *i e$ you s)ou d use a backup con!ro *i e !)a! reco,niTes !)e !ab espace in read%&ri!e (ode+ I* you donF! )ave a backup con!ro *i e$ you can crea!e a ne& one usin, !)e crea!e con!ro *i e co((and+ Basica y$ !)e poin! )ere is !)a! you s)ou d !ake a backup o* !)e con!ro *i e every !i(e you s&i!c) a !ab espaces (od+
