engel - resource consumption of oracle data guard

DBA!ert

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Independant Oracle consultancy

Hotsos Symposium 2005© DBA!ert 2005

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Data Guard Performance Issues

(Cover your Assets with Data Guard)

Carel-Jan Engel

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Carel-Jan Engel

Company: DBA!ert

In IT since 1982

Using Oracle since May, 1985

Member of the Oaktable Network

email: [email protected]

Introduction – who am I ?

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Agenda

Data Guard architectureHA AlternativesData Guard performance Test environmentResultsQ & A

Testhardware: courtesy of

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Data Guard Architecture

Redundant Hardware

Redo

Archiving

Recovery

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StandbyPrimary

redo

LGWR

standby redo

Oracle NetRFS

ARCH

MRP

archivesarchives

ARCH

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Oracle NetStandbyPrimary

redo

LGWR

standby redo

RFS

ARCH

MRP

archivesarchives

ARCH

FAL Oracle Net

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StandbyPrimary

redo

LGWR

standby redo

RFS

ARCH

MRP

archivesarchives

ARCH

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Data Guard benefits

Disaster Recovery

Natural or humanoid

High Availability

Switchover allows HW maintenance

Guaranteed data protection

Synchronous transfer, shutdown if no standby available

Ease of administration

GUI, CLI

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Data Guard benefits

Data Protection Flexibility

3 protection modes to tailor to your needs

Light footprint

Not too heavy transaction penalty

Extra functionality

Read-only standby for reporting

Resource Maximization

Move backup, reporting to standby

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Data Guard Requirements

Enterprise Edition license

On both ends

Any Oracle supported platform

But: same OS/OS level, same Oracle version

Archive Log Mode

Identical directory structure recommended

FORCE_LOGGING recommended

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Data Guard / HA alternatives

RAC

Redundant instances

Single database - SPOF

Complementary

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Mirroring (storage)

Mostly asynchronous

Far from fine granularity

block/track level mirroring

much superfluous changes transferred

redo (2x), arch (2x), control (3x), database

Large bandwidth required

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Quest’s Shareplex

3rd party

supports cross-platform, cross version

expensive

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Data Guard Performance

Performance affected by

redo log volume

log transport

network latency

network throughput

LOG_ARCHIVE_DEST_n settings

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LGWR SYNC PARALLEL

StandbyPrimary

redo

LGWR

standby redo

Oracle NetRFS

ARCH

MRP

archivesarchives

ARCH

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LGWR ASYNC

StandbyPrimary

redo

LGWR

standby redo

RFS

ARCH

MRP

archivesarchives

ARCH

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LGWR SYNC PARALLEL AFFIRM

StandbyPrimary

redo

LGWR

standby redo

Oracle NetRFS

ARCH

MRP

archivesarchives

ARCH

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LOG_ARCHIVE_DEST_n settings

ARCH LGWRLOCATION / SERVICE X XMANDATORY / OPTIONAL X XSYNC / ASYNC X(NO)AFFIRM X(NO)PARALLEL SYNCNET_TIMEOUT ASYNC > 0

SYNC=PARALLEL

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Test harness

reproducible testruns

statistics gathering

logfile gathering

long running jobs

parameterized scenarios

unattended

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Test harness

rc.d concept

execute init, run and exit jobs ordered by name

extended with default settings

init

cleanup, create schema, tablespaces, set parameters, start

databases in correct mode

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Test harness

runkick off the load generation jobs

exit

export perfstat data, schema data

backup alert and trace files

backup load-logging

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Test harness

load-generation with dbaman - James Morle

whitepaper: ‘brewing benchmarks’ - www.oaktable.org

tcl-based extended shell

oci-calls available

controlcenter randomizing ‘think time’ for parallel sessions

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Performance testing

OLTP

order-entry:

5 processes

order creation

order extension

order delivery

invoicing

payment

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Performance testing

order creation

create an order

create 1-10 order lines

64 processes

order extension

extend 25% of the orders

extend to 18 order lines

10 processes

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Performance testing

order delivery

update delivery date

16 processes

invoicing

invoice delivered orders

6 processes

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Performance testing

payment

create payments

amount 25 - 75 % (random), until full payment

4 processes

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Performance testing

OLTP

many small, scattered transactions

100 processes

delays to ‘age-out’ buffers from cache

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Performance testing

OLTP

0.5 hour runs

42824 orders (23 / second) (correct paper, p7!)

258335 orderlines (143 / second)

4329 invoices

1301 payments

25 MB redo / min ==> 1.5 GB/hr:

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Performance testing

No performance degradation measurable.

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Performance testing

OLTP - No performance degradation

System:

1 x Pentium 3.0 GHz/HT

2 disks: 1x 10,000 RP/M, 1x 15,000 RPM

100 Mb Network can keep up easily with the disks

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Performance testing

Batchruns4 parallel sessions:

create table t as select * from all_objects;delete from t;rollback;delete from t;drop table t;

run 100 timesmeasure time

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Scenarios

Per run

70 logswitches (+/- 1)

1762 MB redolog

detailed statistics

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Scenarios

Per run

12 scenarios

One single-server, base-line

10 LGWR, various options

1 ARCH

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Ramdisk redo

Avoiding disk-contention

For re-runnable batches only

Can speed things up quite well,

especially in NOARCHIVELOG mode

Take care, data lost after crash

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Results

Per run

redo size 1762 MB

(7 GB / hour)

70 - 71 logswitches

running appr. 15 minutes

~ 1.9 MB redo / second

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Run1, Redo on Ramdisk, 100Mb0 NONE 1

1 PERF LGWR SYNC NOAFFIRM NOPARALLEL 1.23

2 AVAIL LGWR SYNC AFFIRM NOPARALLEL 1.17

3 PROT LGWR SYNC AFFIRM NOPARALLEL 1.22

4 PERF LGWR SYNC NOAFFIRM PARALLEL 1.21

5 AVAIL LGWR SYNC AFFIRM PARALLEL 1.21

6 PROT LGWR SYNC AFFIRM PARALLEL 1.23

7 PERF LGWR ASYNC 50 1.06




11 PERF ARCH 1.05

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Run2, Redo on Harddisk, 100Mb0 NONE 1











11 PERF ARCH 1.18

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Run3, Redo on Harddisk, 1Gb0 NONE 1











11 PERF ARCH 1.07

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Conclusions

Data Guard slows down a system saturated with batchload

Maximum performance loss in heavy batchload: ~ 27 %

(Relatively) small system with OLTP

No effect from Data Guard measurable:

Speeds vary, 2% slower - 2% faster, results unreliable

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Conclusions

Experience in day-to-day implementations

No significant performance problems during normal work

Large data loads: trade off between either slow run or

detached standby run followed by Instantiation.

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Q & A

[email protected]

engel - resource consumption of oracle data guard

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