Database & Technology 1 _ Milina Ristic _ Why use oracle data guard.pdf

Why
Use
Oracle
Data
Guard?

Milina
Ris7c

TelstraClear,
New
Zealand

The most comprehensive Oracle applications & technology content under one roof

Data
Guard
Func,ons

•  High
availability

•  Data
protec,on

•  Disaster
recovery

•  Repor,ng

•  Backup
and
recovery


Data
Guard
Conﬁgura,ons

•  Physical
Standby

–  block
for
block
iden,cal
copy
of
primary
database

•  Logical
Standby

–  same
logical
informa,on
as
primary
database


Data
Guard
11g

Snapshot
Standby

•  fully
updateable
standby
database

•  tes,ng
on
produc,on
like
data

•  easily
resynchronised
with
produc,on


Data
Guard
11g

Ac,ve
Data
Guard

•  Real-‐,me
repor,ng

•  Fast
incremental
backups

•  Automa,c
correc,on
of
corrupted
blocks

NB:
Requires
separate
license


Ac,ve
Data
Guard

Read-‐only
applica,on
can
perform:

•  Selects

•  Alter
session

•  Call
stored
procedures

•  Call
remote
procedures
via
DB
links

•  DB
links
to
write
to
remote
databases


Apply
Lag
Management
11g

ALTER
SESSION
SET

STANDBY_MAX_DATA_DELAY=600;

ORA-‐03172:
STANDBY_MAX_DATA_DELAY
of

600
seconds
exceeded


Physical
Standby

Primary Standby
database database

Redo
transport

Database Database copy


Beneﬁts
of
Physical
Standby

•  Switchover

•  Failover

•  Repor,ng

•  Backup


Running
Backup
on
Physical
Standby

Primary
Standby

•  4-‐node
RAC
•  4-‐node
RAC

•  NetApp
Filers
•  SAN

•  No
ASM
•  ASM

•  RMAN
•  RMAN

•  TSM
with
TDPO
•  TSM
with
TDPO


Filesystem
to
ASM
and
Back

How
to
duplicate
a
controlfile
when
ASM
is

involved
[ID
345180.1]

How
to
move
a
datafile
from
a
file
system
to

ASM
[ID
390274.1]

How
to
move
a
datafile
from
ASM
to
the
file

system
[ID
390416.1]


Primary RAC database Secondary
Recovery
Catalog

nc
Standby RAC database Primary

sy
Recovery

re
Catalog

backup


Alterna,ves
for
DR

Complex
systems
e.g.

Sybase
database

Oracle
Transparent
Gateway
for
Sybase

Third
party
applica,ons

may
require
alterna,ve
technologies:

• 
SAN
replica,on

• 
snapshot
technology


Logical
Standby

Primary Standby
database database

Oracle Net
Archived Redo Log Apply
Log Files Services

Log Transport Archived Redo
Services Log Files


SQL
Apply
–
Log
Mining

•  READER
–
reads
archived
redo
logs

•  PREPARER
–
generates
logical
change
records

•  BUILDER
–
groups
LCRs
into
transac,ons


SQL
Apply
–
Apply
Processing

•  ANALYZER
–
iden,ﬁes
dependencies

•  COORDINATOR
–
assigns
transac,ons

•  APPLIER
–
applies
transac,ons


Beneﬁts
of
Logical
Standby

•  Switchover

•  Failover

•  Repor,ng

•  Addi,onal
objects


Importance
of
NOT
NULL

TABLE1

ID

NUMBER(5)

NAME
VARCHAR2(20)

TABLE2

ID

NOT
NULL

NUMBER(5)

NAME

VARCHAR2(20)


Importance
of
NOT
NULL

UPDATE
SQL
on
standby
database

UPDATE
table1

SET
name
=
'Smith'

WHERE
(id
=
:b1
OR
id
IS
NULL)
AND

(name
=
:b2
OR
name
IS
NULL)


Tracing
APPLIER

SELECT
PID,
TYPE,
STATUS,
HIGH_SCN

FROM
V$LOGSTDBY

oradebug
setospid
<APPLIER
pid>

oradebug
unlimit

oradebug
event
10046
trace
name
context

forever,
level
12


Tracing
APPLIER

oradebug
setospid
<APPLIER
pid>

oradebug
event
10046
trace
name
context
oﬀ

Trace
ﬁle
will
be
generated
in
bdump

tkprof
<fn>
tkprof.out
explain=
"/
as
sysdba"


Data
Guard
Modes

ALTER
DATABASE
GUARD
{ALL|STANDBY|NONE}

ALL
–
read
only

STANDBY
–
read
only
for
maintained
objects

NONE
–
fully
updateable


Bulk
Updates

Primary

Single
update
of
million
rows

Standby

Million
updates
on
standby


Reinstan,a,ng
Tables

DBMS_LOGSTDBY.INSTANTIATE_TABLE

('HR',
'EMPLOYEES',
'primary_dblink');

•  Log
apply
needs
to
be
stopped

•  Table
is
dropped
and
recreated

•  Addi,onal
grants
and
indexes
are
lost


To
Skip
or
Not
to
Skip

•  Temporary
and
audit
tables

•  User
crea,on

•  Schemas

•  Index
rebuilds

•  Par,,on
maintenance


Par,,on
Maintenance

Produc7on
Repor7ng

•  Keep
12
months
•  Keep
24
months

•  Archive
older
data
•  Drop
older
par,,ons

•  Drop
older
par,,ons


Skipping
Transac,ons

execute
dbms_logstdby.skip

('SCHEMA_DDL',
'HR',
'DEPT');

('DML',
'HR',
'%TEMP');

('ALTER
INDEX',
'%',
'%');


Skipping
Drop
Par,,on

execute
dbms_logstdby.skip

('ALTER
TABLE',
'<schema
name>',

'<object

name>',
'<procedure
name>');


Skipping
Drop
Par,,on

IF
upper(statement)
like
'%DROP%PARTITION%'

THEN

skip_ac,on
:=
sys.dbms_logstdby.SKIP_ACTION_SKIP;

ELSE

skip_ac,on
:=

sys.dbms_logstdby.SKIP_ACTION_APPLY;

END
IF;


Hints
–
What
to
Watch
Out
For

•  Explicitly
using
inappropriate
indexes

•  Hin,ng
full
table
scan

•  Using
too
high
parallel
degree


Unsupported
Opera,ons

Table
compression
up
to
11gR2

workaround
–
triggers

Segment
shrinking

workaround
–
move


Logical
Standby
Tips

•  Sound
primary
database
data
model

•  Beware
bulk
updates

•  Know
the
limits

•  Op,mise
long
running
processes


Q&A

Milina.Ris7c@telstraclear.co.nz


Database & Technology 1 _ Milina Ristic _ Why use oracle data guard.pdf

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Database & Technology 1 _ Milina Ristic _ Why use oracle data guard.pdf