les06.ppt

8/17/2019 les06.ppt

1/44

6Copyright © 2007, Oracle. All rights reserved.

RAC Performance Tuning

8/17/2019 les06.ppt

2/44

Copyright © 2007, Oracle. All rights reserved.6 - 2

Objectives

After completing this lesson, you should be able to:

• Determine RACspecific tuning components

• Tune instance recovery in RAC

• Determine RACspecific !ait events, global en"ueues,and system statistics

• #mplement the most common RAC tuning tips

• $se the Cluster Database Performance pages

• $se the Automatic %or&load Repository 'A%R( in RAC

• $se Automatic Database Diagnostic )onitor 'ADD)( inRAC

8/17/2019 les06.ppt

3/44


CP$ and %ait Time Tuning Dimensions

*calableapplication

*calableapplication

Possiblyneeds *+

tuning

-eedsinstance.RAC

tuning

CP$time

%aittime

-o gain achievedby adding

CP$s.nodes

8/17/2019 les06.ppt

4/44


RAC*pecific Tuning

• Tune for a single instance first/

• Tune for RAC:

– #nstance recovery

– #nterconnect traffic

– Point of seriali0ation can be e1acerbated

• RACreactive tuning tools:

– *pecific !ait events

– *ystem and en"ueue statistics

– 2nterprise )anager performance pages – *tatspac& and A%R reports

• RACproactive tuning tools: – A%R snapshots

– ADD) reports

Certain combinationsare characteristic of

!ell&no!n tuning cases/

8/17/2019 les06.ppt

5/44

Copyright © 2007, Oracle. All rights reserved.6 -

RAC and #nstance or Crash Recovery

Recovery time

*)O-recovers

thedatabase

Remaster en"ueue

resources Remaster cache

resources

3uildrecovery set

)*recovers

4RD

)erge failedredo threads

5

6

7

8

Resource

claim9 Roll for!ard

recovery set

$se informationfor other caches

8/17/2019 les06.ppt

6/44


#nstance Recovery and Database Availability

2lapsed time

D a t a b a s e a v a

i l a b i l i t y

-one

Partial

ull A

3

C D 2

4 ;

5 6 7

9

8

6

8/17/2019 les06.ppt

7/44Copyright © 2007, Oracle. All rights reserved.6 - !

#nstance Recovery and RAC

#nstancecrashes

#nstancestarts

#nstanceopens

#nstance startup<

crash recovery

A*T=*TART=)TTR=TAR42T

#nstancecrashes

#nstancerecovery

starts

Rollingfor!ard

ends#nstancerecovery

>first pass < loc& claim

A*T=*TART=)TTR=TAR42T

?@#-*TA-C2=R2CO?2R/2*TD=C$*T2R=A?A#A32=T#)2

8/17/2019 les06.ppt

8/44Copyright © 2007, Oracle. All rights reserved.6 - "

#nstance Recovery and RAC

• $se parallel instance recovery/

• #ncrease PARALLEL_EXECUTION_MESSAGE_SIZE/

• *et PARALLEL_MIN_SERVERS/

•$se Async #.O/• #ncrease the si0e of the default buffer cache/

8/17/2019 les06.ppt

9/44Copyright © 2007, Oracle. All rights reserved.6 - #0

Analy0ing Cache usion #mpact in RAC

• The cost of bloc& access and cache coherency isrepresented by:

– 4lobal Cache *ervices statistics

– 4lobal Cache *ervices !ait events

• The response time for Cache usion transfers isdetermined by:

– Overhead of the physical interconnect components

– #PC protocol

– 4C* protocol• The response time is not generally affected by dis& #.O

factors/

8/17/2019 les06.ppt

10/44Copyright © 2007, Oracle. All rights reserved.6 - ##

Typical atencies for RAC Operations

A%R Report atency -ame o!er3ound

Typical $pper3ound

Average time to process cr bloc& re"uest B/5 5 5B

Avg global cache cr block receive tie !"# B/7 9 56

Average time to process current bloc& re"uest B/5 7 67

Avg global cache c$rre%t block receive tie!"# B/7 7B

8/17/2019 les06.ppt


%ait 2vents for RAC

• %ait events help to analy0e !hat sessions are !aitingfor/

• %ait times are attributed to events that reflect theoutcome of a re"uest:

– Placeholders !hile !aiting

– Precise events after !aiting

• 4lobal cache !aits are summari0ed in a broadercategory called Cluster %ait Class/

• These !ait events are used in ADD) to enable Cacheusion diagnostics/

8/17/2019 les06.ppt


%ait 2vent ?ie!s

V&ACTIVE_SESSION_'ISTOR(

V&SESSION_EVENT

V&S(STEM_EVENT

V&SESSION_)AIT_'ISTOR(

%aits for an event by a session

ast 5B !ait eventsfor each active session

Activity of recent active sessions

Total !aits for an event

V&SESSION_)AIT2vents for !hich

active sessions are !aiting

V&SESSION_)AIT_CLASS%aits for a !ait event classby a session

V&S*LSTATS#dentify *+ statements impactedby interconnect latencies

8/17/2019 les06.ppt


4lobal Cache %ait 2vents: Overvie!

gc current.crE multibloc&E re"uest

gc current.crE 6.7E!ay gc current.crE bloc& busy

Fust re"uested'placeholder(

Received after t!o or three net!or&

hops, immediately after re"uest

Received but not sent immediately

gc current.crE grant 6!ay

-ot received and not masteredlocally/ 4rant received immediately/

gc current grant busy

-ot received and not masteredlocally/ 4rant received !ith delay/

gc current.crE bloc&.grantE congested

3loc& or grant received !ith delaybecause of CP$ or memory lac&

gc current.crE failure.retryE

-ot received because of failure

gc buffer busy

3loc& arrival timeless than buffer pin time

8/17/2019 les06.ppt


+,-a. 3loc& Re"uest: 21ample

SGA/

SGA+

4%R4%R:

og sync

%ait complete:gc c$rre%t block +,-a.

%ait:gc c$rre%t block re1$e"t

Direct send

3loc& transfer

5

6

7

4P

)*

8/17/2019 les06.ppt


2,-a. 3loc& Re"uest: 21ample

SGA/

SGA+

4%R

)*

4P

%ait complete:gc c$rre%t block 2,-a.


Directmessage

3loc& transfer

)*Resource

)aster

5 6

7

9

8/17/2019 les06.ppt

16/44Copyright © 2007, Oracle. All rights reserved.6 - #!

+,-a. 4rant: 21ample

SGA/

SGA+

4P

%ait complete:gc c$rre%t gra%t +,-a.


Directmessage

4rant message

)*Resource

)aster

5

6

7

8/17/2019 les06.ppt

17/44Copyright © 2007, Oracle. All rights reserved.6 - #"

4lobal 2n"ueue %aits: Overvie!

• 2n"ueues are synchronous/

• 2n"ueues are global resources in RAC/

• The most fre"uent !aits are for:

• The !aits may constitute serious seriali0ation points/

TG T)

;%

*+

$*

TA

8/17/2019 les06.ppt

18/44Copyright © 2007, Oracle. All rights reserved.6 - 20

*ession and *ystem *tatistics

• $se V&S(SSTAT to characteri0e the !or&load/

• $se V&SESSTAT to monitor important sessions/

• V&SEGMENT_STATISTICS includes RAC statistics/

• RACrelevant statistic groups are:

– 4lobal Cache *ervice statistics

– 4lobal 2n"ueue *ervice statistics

– *tatistics for messages sent

• V&EN*UEUE_STATISTICS determines the en"ueue !ith

the highest impact/• V&INSTANCE_CAC'E_TRANS3ER brea&s do!n 4C*

statistics into bloc& classes/

8/17/2019 les06.ppt

19/44Copyright © 2007, Oracle. All rights reserved.6 - 2#

)ost Common RAC Tuning Tips

• Application tuning is often the most beneficial/

• Resi0ing and tuning the buffer cache

• Reducing long fulltable scans in OTP systems

• $sing Automatic *egment *pace )anagement

• #ncreasing se"uence caches

• $sing partitioning to reduce interinstance traffic

• Avoiding unnecessary parsing

• )inimi0ing loc&ing usage

• Removing unselective inde1es

• Configuring interconnect properly

8/17/2019 les06.ppt


#nde1 3loc& Contention: Considerations

RACB5 RACB6

#nde1bloc&

*plit inprogress

%ait events

e%14 TX , i%5e6co%te%tio%

gc b$77er b$".

gc c$rre%t block

b$".

gc c$rre%t "8lit

*ystem statistics

Lea7 %o5e "8lit"

9ra%ch %o5e "8lit" E6cha%ge 5ea5lock"

gc" re7$"e 6i5

gc" a"t 6i5

Service ITL -ait"

8/17/2019 les06.ppt


Oracle *e"uences and #nde1 Contention

Can contain 8BB ro!s

5>8BBBB 8BBB5>5BBBBB

CAC'E :;;;; NOOR

RACB5 RACB6

8/17/2019 les06.ppt


$ndo 3loc& Considerations

*4A6*4A5

>

ChangesReads

#nde1

Additionalinterconnect traffic

$ndo $ndo

8/17/2019 les06.ppt


;igh%ater )ar& Considerations

;%)

;eavyinserts

;eavyinserts

-e! e1tent

%ait events

e%14 ') ,co%te%tio%

gc c$rre%t gra%t

RACB5 RACB6

8/17/2019 les06.ppt


Concurrent Cross#nstance Calls: Considerations

*4A5 *4A6

CHPT

Table5

Table6

Table5

Table6

Dirtybloc&

CHPT

Truncate Table5 Truncate Table6

Crossinstance call

5

67 9

8/17/2019 les06.ppt

25/44Copyright © 2007, Oracle. All rights reserved.6 - 2!

)onitoring RAC Databaseand Cluster Performance

Directly from Database Control and 4rid Control:

• *tatus of each node in the cluster

• Aggregated alert messages across all the instances

• Revie! issues that are affecting the entire cluster oreach instance

• )onitor cluster cache coherency statistics

• Determine if any of the services for the cluster databaseare having availability problems

• Revie! any outstanding Cluster!are interconnect alerts

Database

#nstances

8/17/2019 les06.ppt

26/44

Copyright © 2007, Oracle. All rights reserved.6 - 2"

Cluster Database Performance Page

8/17/2019 les06.ppt

27/44


Determining Cluster ;ost oad Average

8/17/2019 les06.ppt

28/44

Copyright © 2007, Oracle. All rights reserved.6 - 3#

Determining 4lobal Cache 3loc& Access atency

8/17/2019 les06.ppt

29/44


Determining Average Active *essions

8/17/2019 les06.ppt

30/44


Determining Database Throughput

8/17/2019 les06.ppt

31/44


Determining Database Throughput

8/17/2019 les06.ppt

32/44


Accessing the Cluster Cache Coherency Page

3loc&Class

*egmentname

*egmentname

8/17/2019 les06.ppt

33/44


Accessing the Cluster Cache Coherency Page

8/17/2019 les06.ppt

34/44


?ie!ing Cluster #nterconnects Page

8/17/2019 les06.ppt

37/44


A%R *napshots in RAC

**A$G

*4A '#nstn(

#nmemory

statistics

I:BB a/m/

J:BB a/m/

:BB a/m/

K:BB a/m/

K:BB a/m/

*4A '#nst5(

#nmemorystatistics

>

MMON Coor5i%ator

MMON

A%R tables

8/17/2019 les06.ppt

39/44


Automatic Database Diagnostic )onitor for RAC

Database ADD)

A%R

#nstance ADD)

*elfdiagnostic engine

#nst5 #nstn

…

8/17/2019 les06.ppt

40/44


• #dentifies the most critical performance problems forthe entire RAC cluster database

• Runs automatically !hen ta&ing A%R snapshots

• Performs database!ide analysis of:

– 4lobal resources 'for e1ample #.O and global loc&s(

– ;ighload *+ and hot bloc&s

– 4lobal cache interconnect traffic

– -et!or& latency issues

– *&e! in instance response times• #s used by D3As to analy0e cluster performance

• 2liminates need to investigate n reports to spotcommon problems

Automatic Database Diagnostic )onitor for RAC

8/17/2019 les06.ppt

41/44


%hat Does ADD) Diagnose for RACL

• atency problems in interconnect

• Congestion 'identifying top instances affecting theentire cluster(

• Contention 'buffer busy, top objects etc/(

• Top consumers of multibloc& re"uests

• ost bloc&s

• #nformation about interconnect devices '!arns aboutusing P$3#C interfaces(

• Throughput of devices: ;o! much of it is used byOracle and for !hat purpose '4C, loc&s, P+(

8/17/2019 les06.ppt

42/44


2) *upport for ADD) for RAC

8/17/2019 les06.ppt

43/44


*ummary

#n this lesson, you should have learned ho! to:

• Determine RACspecific tuning components

• Tune instance recovery in RAC

• Determine RACspecific !ait events, global en"ueues,and system statistics

• #mplement the most common RAC tuning tips

• $se the Cluster Database Performance pages

• $se the Automatic %or&load Repository in RAC

• $se Automatic Database Diagnostic )onitor in RAC

8/17/2019 les06.ppt

44/44

Practice I: Overvie!

This practice covers studying a scalability case by usingthe ADD)/

les06.ppt

Documents

Transcript of les06.ppt