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8/13/2019 Rman Tutorials

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RMAN TUTORIALS

An RMAN channel represents one stream of data to a device type and

corresponds to one server session. Allocation of one or more RMAN

channels is necessary to execute most ac!up and recovery commands.

As illustrated in "i#ure$ each channel estalishes a connection from the

RMAN executale to a tar#et or auxiliary dataase instance y startin#

a server session on the instance. The server session performs theac!up$ restore$ and recovery operations. Only one RMAN session

communicates %ith the allocated server sessions.

&ou can either allocate channels manually %ithin a RUNloc!$ or

preconfi#ure channels for use in all RMAN sessions usin# automatic

channel allocation. RMAN comes preconfi#ured %ith a DISKchannel

that you can use for ac!ups and copies to dis!. &ou can also run the

CONFIGURECHANNELcommand RMAN to specify automatic channels

to dis! or tape. In this %ay$ you do not have to allocate channels every

time you perform a ac!up$ restore$ or recovery operation.

'hen you run a command that re(uires a channel$ and you do not

allocate a channel manually$ then RMAN automatically allocates the

channels usin# the options specified in the CONFIGUREcommand. "or

the BACKUPcommand$ RMAN allocates only a sin#le type of channel$

such as DISKor sbt. "or the RESTOREcommand and the variousmaintenance commands )for example$ DELETE*$ RMAN determines

%hich device types are re(uired$ and allocates all necessary channels.

If you specify channels manually$ then theALLOCATE CHANNELcommand

)executed only %ithin a RUNcommand* andALLOCATE CHANNEL FOR

MAINTENANCEcommand )executed only at the RMAN prompt* specify the


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type of I+O device that the server session %ill use to perform the

ac!up$ restore$ or maintenance operation.

Unless you manually run anALLOCATECHANNELcommand$ RMAN

allocates automatic channels accordin# to the settin#s in these

commands,

CONFIGUREDEVICE TYPE...PARALLELISM

CONFIGUREDEFAULTDEVICETYPE

CONFIGURECHANNELDEVICETYPE

CONFIGURECHANNELnDEVICETYPE

"or example$ you can issue the follo%in# commands at the RMAN

prompt,

BACKUP DATAFILE 3;RUN { RESTORE TABLESPACE uses; !

RMAN automatically allocates channels accordin# to values set %ith the

CONFIGUREcommand in the follo%in# cases,

&ou use commands such as BACKUP$ RESTORE$ or DELETE

outside of a RUNloc!.

&ou use commands %ithin a RUNloc! ut do not allocate any

channels %ithin the RUNloc!.

&ou can override automatic channel allocation settin#s y manually

allocatin# channels %ithin a RUNloc!. &ou cannot mix automatic and

manual channels$ so manual channels al%ays override automatic

channels. "or example$ you override automatic channel allocation %hen

you issue a command as follo%s,

RUN{ ALLOCATE CHANNEL "# DEVICE TYPE sbt;

BACKUP DATABASE PLUS ARCHIVELOG;!

RMAN internally handles paralleli-ation of BACKUP$ COPY$ and

RESTOREcommands. &ou only need to specify,

MultipleALLOCATE CHANNELcommands


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The oects that you %ant to ac! up$ copy$ or restore

RMAN executes commands se(uentially/ that is$ it completes the

current command efore startin# the next one. 0arallelism is exploited

only %ithin the context of a sin#le command. 1onse(uently$ to create

three ac!ups of a datafile$ issue a sin#le BACKUPcommand specifyin# all

three datafiles rather than three separate BACKUPcommands.

In Oracle2i$ theALLOCATE CHANNELcommand causes RMAN to contact the

media mana#er %henever the type specified is other than DISK. In

releases efore Oracle2i$ theALLOCATE CHANNELcommand does not cause

RMAN to contact the media mana#er/ RMAN does not call the media

mana#er unless a BACKUP$ RESTORE$ or RECOVERcommand is issued.

Note:

'hen you specify DEVICETYPE DISK%ith any version of RMAN$ RMAN

does not allocate operatin# system resources other than for the creationof the server session and does not call the media mana#er.

'hen you execute the BACKUPcommand$ you create one or more ac!up

sets. A ac!up set$ %hich is a lo#ical oect$ contains one or more

physical ac!up pieces. 3y default$ one ac!up set contains one ac!up

piece. 3ac!up pieces are operatin# system files that contain the ac!ed

up datafiles$ control files$ or archived redo lo#s. "or example$ you can

ac! up ten datafiles into a sin#le ac!up set containin# a sin#le ac!up

piece )that is$ a sin#le output file*. &ou cannot split a file across different

ac!up sets or mix archived lo#s and datafiles into one ac!up set.

A ac!up set is a complete set of ac!up pieces that ma!e up a full or

incremental ac!up of the oects specified in the BACKUPcommand.

3ac!up sets are in an RMAN4specific format. An ima#e copy$ %hich is a

complete ima#e of a sin#le datafile$ control file$ or archived lo#$ is not in

an RMAN4specific format.

BACKUP DATABASE;BACKUP TABLESPACE uses$ t%%&s;

BACKUP 'SPFILE( 'CURRENT CONTROL FILE(;BACKUP BACKUPSET #);BACKUP DATAFILECOPY *+t,-+sste,/#.0b1*;

'hen ac!in# up datafiles$ the tar#et dataase must e mounted or

open. If the dataase is inARCHIVELOGmode$ then the tar#et can e open

or closed, you do not need to close the dataase cleanly. If the dataase


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is inNOARCHIVELOGmode$ then you mustclose it cleanly efore ma!in# a

ac!up.

RMAN -e1%,s compression%2 ts b4"5u-s$ 67"7,e42s t74t 04t41&e b&%"5s t74t 748e 2e8e bee2use0 4e 2%t b4"5e0 u-. I,49e "%-es %1 4 04t41&e$7%6e8e$ 4&64s "%2t42 4&& 04t41&e b&%"5s.

Table Backup Types

BackupType Definition

"ullA ac!up that is not incremental. A full ac!up includes

all used data loc!s in the datafiles. "ull ac!ups of

control files and archived lo#s al%ays include all loc!s in

the files.

Note, A full ac!up is different from a %hole dataase

ac!up$ %hich is a ac!up of all datafiles and the current

control file.

Incremental A ac!up of datafiles that includes only the loc!s that

have chan#ed since a previous incremental ac!up.

Incremental ac!ups re(uire a full or incremental level 5

ac!up to serve as a asis.

Online A ac!up of online$ read+%rite datafiles %hen the dataaseis open.

Note, 6o not put a talespace in ac!up mode %ith the

ALTERTABLESPACEBEGINBACKUPstatement. RMAN

uses a different method to #uarantee consistency in online

ac!ups.

1losed A ac!up of any part of the tar#et dataase %hen it is

mounted ut not open. 1losed ac!ups can e consistentor inconsistent.

1onsistent A ac!up ta!en %hen the dataase is mounted )ut not

open* and %as notcrashed or shut do%n %ith theABORT

option prior to mountin#. The chec!point S1Ns in the


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BackupType Definition

datafile headers match the header information in the

control file and none of the datafiles has chan#es eyond

its chec!point. 1onsistent ac!ups can e restored %ithout

recovery.

InconsistentA ac!up of any part of the tar#et dataase %hen

It is open.

It crashed or a SHUTDO:NABORT%as run

prior to mountin#.

An inconsistent ac!up re(uires recovery to ecome

consistent.

How Incremental Backups Work

7ach data loc! in a datafile contains a system chan#e numer )S1N*$

%hich is the S1N at %hich the most recent chan#e %as made to

the loc!. 6urin# an incremental ac!up$ RMAN reads the S1N

of each data loc! in the input file and compares it to the

chec!point S1N of the parent incremental ac!up. RMAN reads

the entire file every time %hether or not the loc!s have een

used.

The parent ac!up is the ac!up that RMAN uses for comparin# the

S1Ns. If the current incremental is a differential ac!up at level n$ then

the parent is the most recent incremental of level nor less. If the current

incremental is a cumulative ac!up at level n$ then the parent is the

most recent incremental of level n48 or less. If the S1N in the input data

loc! is #reater than or e(ual to the chec!point S1N of the parent$ then

RMAN copies the loc!.

The BACKUPcommand can ac! up the follo%in# types of files,

6ataase$ %hich includes all datafiles as %ell as the current

control file and current server parameter file

Talespaces )except for locally4mana#ed temporary talespaces*

1urrent datafiles

1urrent control file

Archived redo lo#s


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1urrent server parameter file

3ac!up sets

RMAN does not ac! up the follo%in#,

Online redo lo#s

Transported talespaces efore they have een made read+%rite

1lient4side initiali-ation parameter files or noncurrent server

parameter files.

If CONFIGURECONTROLFILEAUTOBACKUPis ON)y default it is

OFF*$ then RMAN automatically ac!s up the control file and the

current server parameter file )if used* in the follo%in# circumstances,

After every BACKUPor COPYcommand issued at the RMAN

prompt.

'henever a BACKUPor COPYcommand %ithin a RUNloc! is

follo%ed y a command that is neither BACKUPnor COPY. At the end of every RUNloc! if the last command in the loc!

%as either BACKUPor COPY.

After dataase structural chan#es such as addin# a ne%

talespace$ alterin# the state of a talespace or datafile )for

example$ rin#in# it online*$ addin# a ne% online redo lo#$

renamin# a file$ addin# a ne% redo thread$ and so forth. This type

of autoac!up$ unli!e autoac!ups that occur in the precedin#

circumstances$ is only on dis!. &ou can run CONFIGURECONTROLFILE

AUTOBACKUPFORDEVICETYPEDISKto set a nondefault dis! location.Note that the autoac!up never causes the associated structural

chan#e to fail. "or example$ if you add a datafile$ and if the

resultin# autoac!up fails$ then the datafile addition is still

successful.

Test Backups Using RMAN

ou can run t!e BACKUP...VALIDATEcomman" to "o t!e

following:

1hec! datafiles for physical and lo#ical corruption 1onfirm that all dataase files exist and are in the correct

locations


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