db mirroring

7/27/2019 Db Mirroring

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Copyright 2009 all rights reservedCopyright 2009 all rights reserved

11DB Architechs, USADB Architechs, France

Database Mirroring & SnapshotsDatabase Mirroring & Snapshots

SQL Server 2008SQL Server 2008


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AgendaAgendaSQL Server User GroupSQL Server User Group

Database MirroringDatabase MirroringSQL Server 2008SQL Server 2008

Database Mirroring 2005 vs 2008Database Mirroring 2005 vs 2008 benchmarkbenchmark

Database SnapshotsDatabase SnapshotsSQL Server 2008SQL Server 2008

SQL Performance &SQL Performance &Tuning Tool (SQL Shot !)Tuning Tool (SQL Shot !)


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Copyright 2009 all rights reservedCopyright 2009 all rights reserved44

Database ArchitechsDatabase Architechs

Primary ServicesPrimary Services

Database Design

Data Analysis& Modeling

Data Architecture

Performance &Tuning

High Availability

Master DataManagement

Distributed Data &Data Replication

Business Intelligence &Data Delivery

Platforms

Database Education& Training


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Past and CurrentPast and Current

Intel Applied Materials

Cisco Apple Computers

Charles Schwab PG&E

Aplia Thomson Learning

AGIS Sybase

Veritas Symantec Corporation

Honda Motors Nissan MotorsToshiba Computers Breg International

Juniper Networks CSAA

Safeway Stores Federal Express

Wells Fargo Bank of AmericaRobert Half Merrill Lynch

Metalinc many others.

Customers


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Database Mirroring?Database Mirroring?

A complete copy of a database that is created andmaintained with as up to the second completenessthat is possible a mirror image.

AdventureWorks DB = AdventureWorks DB


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Whats new or improved? Compression in log transactions across topology Various other performance enhancements Page fixing on the mirror side (AUTO) 3 years of production execution success!


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SQL Server 2008

Source

CallOne DB

CallOne DB

SQL Server 2008

SecondaryServer

Destination

translog

\Backup\CallOne_tlog_200405141120.TRN

TxnLog

backupsPrimaryServer

TxnLogCopies

\LogShare\CallOne_tlog_200405141120.TRN TxnLogRestores

MSDB DB

SQL Server 2008

MonitorServer

Monitor

Lastlogshipped

DelayAnswer

Delay betweenlogs loaded

Delay Answer

Log ShippingLog Shipping

Dont build on this, it is being deprecated !


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DBDB

MirroringMirroring

MSDB DB

SQL Server 2008

SQL Server xyz

WitnessServer

Adventure

Works DB

SQL Server 2008

Mirror Server

translog

Principal

Server

translog

Adventure

Works DB

Network

Client Client ClientClient

B

C

A

D

D


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CopyCopy--onon--write Technologywrite TechnologyThe new copy-on-write technology that Microsoft has created, is at the core ofthe database mirroring capability. A transaction from a client connection to the

principal server (arrow label A) is written to the adventure works database

(label D). Once the transaction is written to the principal servers transaction log,it is immediately copied (arrow label B) and written to the Mirror Server (alsolabeled D). When this physical log record is written to the mirror server, it sendsback an acknowledgement (arrow label C) to the principal of its write success.This is the copy-on-write technology. The end result is that the mirror server

is in the exact same state as the principal server (when the physical log recordhas been successfully written on the mirror side).


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DB Mirroring TermsDB Mirroring TermsThe Principal database server - is the source of the mirroring. You can mirror one

or more databases on a single SQL Server instance to another SQL Server instance.You cannot mirror a database on one SQL Server instance to itself (the same SQLServer instance).

The Mirror database server - will be the recipient of the mirroring from the principaldatabase server. This mirrored database will be kept in a hot standby mode andcannot be used directly in any way. In fact, once you have configured database

mirroring, this database will show its status as in continuous restore mode.

The Witness database server - is used when you want to be continuously checkingto see if any failures have occurred to the primary database server and to help makethe decision to failover to the mirror database server. It is optional, but a sound wayto configure database mirroring. If you do not identify a witness server, the principal

and mirror are left on their own to decide to fail-over or not.


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DB Mirroring ModesDB Mirroring ModesHigh-availability mode, High-protection mode, and High-performance mode.

Synchronous operation - a committed transaction will be committed (written) on

both partners of the database mirroring pair. This obviously adds some latency costto a complete transaction (it is across two servers). High-availability mode andHigh-protection mode use synchronous operations (termed High safety)

Asynchronous operation - transactions commit without waiting for the mirror server

to write the log to disk. This can speed up performance significantly.High-performance mode uses asynchronous operations.

Whether the operations are asynchronous or synchronous depends on thetransaction safety setting. This is controlled by the SAFETY option whenconfiguring with Transact-SQL commands (Set to FULL for synchronousoperations, set to OFF for asynchronous operations).

[you must sacrifice levels of protection for performance]


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FailFail--over methodsover methodsAutomatic failover - is enabled with a three-server configuration; a principal, amirror, and a witness server. Synchronous operations are required and the mirror

database must already be synchronized (in sync with the transactions as they are

being written to the principal). Role switching is done automatically. This is for high-availability mode.

Manual failover - is needed when there is no witness server and is also doingsynchronous operations. The principal and the mirror are connected to each other

and the mirror database must already be synchronized. Role switching is donemanually. This is for high-protection mode.

Forced Service - in the case where there is a mirror server available, but it mightnot be synchronized. It can be forced to take over when the principal server has

failed. This will possibly have data loss, since the transactions were notsynchronized. This is for either high-protection or high-performance mode.


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Cannot be used with:Cannot be used with:


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Database Mirroring cannot be used for any of SQL Servers internaldatabases TempDB, Master DB, MSDB, or Model DB.

Database Mirroring is NOT supported in SQL Server WorkgroupEdition or Express Edition. However, these server editions could beused as Witness servers.

You cannot have database mirroring for databases enabled withFILESTREAM storage.


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HAHA

Extreme Availability

High Availability

Standard Availability

Acceptable Availability

Marginal Availability

Near zero downtime!

Minimal downtime

With some downtimetolerance

Non-critical Applications

Non-production Applications

8,760 hours/year | 168 hours/week | 24 hours/day

525,600 minutes/year | 7,200 minutes/week | 1,440 minutes/day

(99.5% - 100%)

(95% - 99.4%)

(83% - 94%)

(70%-82%)

(up to 69%)

Characteristic Availability Range

Availability Rangedescribes the percentage of time relative to the planned hours of operations

Availability Continuum


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Windows 2003 EE

Windows 2003 EE

SQL Server 2008

(Virtual SQL Server) SCSI

Local

Binaries

LocalBinaries

CLUSTER1

SQL Clustering basic configurationSQL Clustering basic configuration

S:

C:

C:

Master DB

TempDBAppl 1 DB

CLUSTER2

SQL Server 2008 (physical)

SQL Server 2008 (physical)

SQL

Connections

QuorumDisk

Q:

VSQLSERVER2008

Cluster Group

Resources

MS DTCSQL Agent

MSCS

MSCS

SQL Full TextSearch



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ExampleExample

ConfiguratioConfiguratio

nn

MSDB DB

SQL Server 2008

SQL Server 2008

Witness

Server

Adventure

Works DB

SQL Server 2008

Mirror Server

translog

Principal

Server

translog

Adventure

Works DB

Instance: SQL08DE01 Instance: SQL08DE02

Instance: SQL08DE03

Endpoint name: EndPoint4DBMirroring1430 Endpoint name: EndPoint4DBMirroring1440

Endpoint name: EndPoint4DBMirroring1450

TCP: Listener_Port: 1430 TCP: Listener_Port: 1440

TCP: Listener_Port: 1450

Role: PARTNER Role: PARTNER

Role: WITNESS


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Creating EndpointsCreating Endpoints

-- create endpoint for PRINCIPAL server --CREATE ENDPOINT [EndPoint4DBMirroring1430]

STATE=STARTED

AS TCP (LISTENER_PORT = 1430, LISTENER_IP = ALL)FOR DATA_MIRRORING (ROLE = PARTNER,

AUTHENTICATION = WINDOWS NEGOTIATE, ENCRYPTION = REQUIRED ALGORITHM RC4)

01/05/2009 13:17:23,spid55,Unknown,The Database Mirroring protocol transport is now listening forconnections.01/05/2009 13:17:23,spid55,Unknown,Server is listening on [ 'any' 1430].

SQL Server Log entry



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Creating EndpointsCreating Endpoints-- create endpoint for MIRROR server --CREATE ENDPOINT [EndPoint4DBMirroring1440]

STATE=STARTED

AS TCP (LISTENER_PORT = 1440, LISTENER_IP = ALL)

FOR DATA_MIRRORING (ROLE = PARTNER,AUTHENTICATION = WINDOWS NEGOTIATE

, ENCRYPTION = REQUIRED ALGORITHM RC4)

-- create endpoint for WITNESS server --CREATE ENDPOINT [EndPoint4DBMirroring1450]

STATE=STARTED

AS TCP (LISTENER_PORT = 1450, LISTENER_IP = ALL)

FOR DATA_MIRRORING (ROLE = WITNESS,AUTHENTICATION = WINDOWS NEGOTIATE

, ENCRYPTION = REQUIRED ALGORITHM RC4)



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Backup PrincipalBackup Principal BACKUP DATABASE [AdventureWorks]BACKUP DATABASE [AdventureWorks]

TO DISK = N'C:TO DISK = N'C:\\Program FilesProgram Files\\Microsoft SQLMicrosoft SQL

ServerServer\\MSSQL10.SQL08DE01MSSQL10.SQL08DE01\\MSSQLMSSQL\\BackupBackup\\AdventureWorks4Mirror.bak'AdventureWorks4Mirror.bak'

WITH FORMATWITH FORMAT

GOGO

---- Processed 17672 pages for database 'AdventureWorks', file 'AdveProcessed 17672 pages for database 'AdventureWorks', file 'AdventureWorks_Data' on file 1.ntureWorks_Data' on file 1.

---- Processed 3 pages for database 'AdventureWorks', file 'AdventurProcessed 3 pages for database 'AdventureWorks', file 'AdventureWorks_Log' on file 1.eWorks_Log' on file 1.

---- BACKUP DATABASE successfully processed 17675 pages in 7.718 secBACKUP DATABASE successfully processed 17675 pages in 7.718 seconds (17.890 MB/sec).onds (17.890 MB/sec).

BACKUP LOG [AdventureWorks] TOBACKUP LOG [AdventureWorks] TO

DISK = N'C:DISK = N'C:\\Program FilesProgram Files\\Microsoft SQLMicrosoft SQL

ServerServer\\MSSQL10.SQL08DE01MSSQL10.SQL08DE01\\MSSQLMSSQL\\BackupBackup\\AdventureWorks4MirrorLog.bak'AdventureWorks4MirrorLog.bak'

GOGO

---- Processed 1849 pages for database 'AdventureWorks', file 'AdvenProcessed 1849 pages for database 'AdventureWorks', file 'AdventureWorks_Log' on file 1.tureWorks_Log' on file 1.

---- BACKUP LOG successfully processed 1849 pages in 0.862 seconds (BACKUP LOG successfully processed 1849 pages in 0.862 seconds (16.757 MB/sec).16.757 MB/sec).


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1111



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1313



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1414



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1515



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1616


Instance: SQL2008xyz


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PH TopologyPH Topology

SQL Server 2008

AdventureWorks DB

SQL Server 2008

Mirror Server

translog

Principal

Server

translog

AdventureWorks DB


Instance: SQL2008zzz

Endpoint Name: endpoint4mirroring


Role: PARTNER

Role: PARTNER

PHTopology

SQL Server 2008

Principal

Server

Active

Passive

Cluste

red

OLTPApp

lication

Replica

tion


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DB Mirroring 2005 BenchmarksDB Mirroring 2005 Benchmarks

Send Rate

Repl_rows stored procedure 9999999


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DB Mirroring 2008 BenchmarksDB Mirroring 2008 BenchmarksSend Rate

41% More


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Restore Rate


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DB Mirroring 2008 BenchmarksDB Mirroring 2008 BenchmarksRestore Rate

52% more


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DB Mirroring Benchmark SummaryDB Mirroring Benchmark Summary

Overall send rate 41 % faster (2005 vs 2008)Overall restore rate 52% faster (2005 vs 2008)

Overall availability topology inherits the restore rate ~ 50% more available

Example:

743 ms Transaction (in 2005 mirroring configuration)

379 ms Transaction (in 2008 mirroring configuration)

In failover, what would have been 20 seconds before mirror becomes principalturns into roughly 8-10 seconds (or 3 seconds turns into 1.5 seconds, so on).


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SnapshotsSnapshots


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0101SQL Server 2008

AdventureWork

s DB

translog

Source

Server

DatabaseSnapshot

Point-i

n-time

Repo

rting

Users

(Rea

d-Only)

Transactional

Users

--- Reverting --- if needed ---RESTORE DB

AdventureWorksFROM DATABASE_SNAPSHOT = xyz

CREATE DB xyzAS SNAPSHOT OF

AdventureWorks


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0202SQL Server 2008

SQLServer

AdventureWork

s DB

SnapshotAdventureWork

s DB

Source Data

Pages

Empty Sparse fileof a Snapshot just created

(no updates to originaldata pages have occurred yet)

SparseFile

Pages

Source

S


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0303SQL Server 2008

SQLServer

AdventureWork

s DB


s DB

SourceData

Pages

System Catalog

of changed pages

Copy of original

pages for snapshotonly when a page is changed

(Copy-on-write)

SparseFile

Pages

Source

Snapshot


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Copyright 2009 all rights reservedCopyright 2009 all rights reserved 4545

0404SQL Server 2008

SQLServer

AdventureWork

s DB


s DB

Source Data

Pages

System Catalog

of changed pages

Sparse

FilePages

SELECT ..data.

FROM AdventureWorks

SNAPSHOT

Snapshot

Users

Transactional


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0505

SQL Server 2008

SQLServer

AdventureWork

s DB


s DB

Data

Pages

System Catalog

of changed pages Copy of originalpages for snapshot use

only when a page is changed(Copy-on-write)

SparseFile

Pages

Transactional

Users

translog

UpdateRowA

B

B

B

B

C

Committed


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0606SQL Server 2008

AdventureWorks

DB

translog

Source

Server

DatabaseSnapshot

AllUse

rs

DatabaseSnapshot

DatabaseSnapshot

6:00AM Snapshot

12:00PM Snapshot

6:00PM SnapshotRestore from

Any Point-in-timeSnapshot if neededDatabaseSnapshot

12:00AM Snapshot

UPDATE AWSource.tableXset xyz =

FROM AWSnapshot6:00AM.tableX


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0707SQL Server 2008

AdventureWorks

DB

Source

Server

DatabaseSnapshot

Users

SAFEGUARD Snapshot(Before the mass changes)

Restore from snapshot

(if changes are not correct)

Generating

Mass Changes

UPDATE AWSource.tableXset xyz =

FROM AWSafegaurd6:00AM.tableX


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0808SQL Server 2008

AdventureWorks

DB

Source

Server

DatabaseSnapshot

Te

stingUsers

BEFORE TEST Snapshot

Restore from the BEFORE snapshot

after testing cycle is complete and can

continue with next test.

Trans


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0909SQL Server 2008

AdventureWorks

DB

translog

Source

Server

DatabaseSnapshot

nsactional

Use

rs

DatabaseSnapshot

DatabaseSnapshot

6:00AM Reporting Snapshot

12:00PM Reporting Snapshot

6:00PM Reporting Snapshot

DatabaseSnapshot

12:00AM Reporting Snapshot

Point-in-tim

e

Reporting

Users

(Read-Only)


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1010

MSDB DB

SQL Server 2008

SQL Server 2008

Witness

Server

AdventureWorks

DB

SQL Server 2008

Mirror Server

translog

Principal

Server

Netw

ork

Netw

ork

DatabaseSnapshot

Reporti

ngUse

rs

AdventureWorks

DB

translog

DatabaseSnapshot

Ifthisserverno

de

becomesthemirror.




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PH Topology With SnapshotsPH Topology With Snapshots

SQL Server 2008

Adventure

Works DB

SQL Server 2008

Mirror Server

translog

Principal

Server

translog

Adventure

Works DB

Instance: SQL2008zzz



Role: PARTNER

Role: PARTNER

PH

Topology

SQL Server 2008

Principal

Server

Active

Passive

Clustered

OLTPApplication

Replic

ation

NetworkNetwork

Reporting Users

DatabaseSnapshot

DB Mirror andDB Mirror andPublisher


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DB Mirror andDB Mirror and

ReplicationReplicationSQL Server 2008

Principal

Server

SQL Server 2008

Mirror

Server

SQL Server 2008

WitnessServer

SQL Server 2008

Principal

Server

SQL Server 2008

Mirror

Server

SQL Server 2008

Subscriber

SQL Server 2008

Subscriber

Distributor


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Distributing DataDistributing DataData Access Latency Autonomy

Sites

(locations)

Frequency Network Machines Owner Other

Read OnlyReporting short high many high

fast/stable

1server/site

1 OLTPsite

Each site onlyneeds regionaldata

Central Publisher

Transactional repl

filter by region

REPLICATION

Read Only

Reportinglong high many low

fast/

stable

1

server/site1 OLTP

site

Each site onlyneeds regionaldata

Central PublisherSnapshot repl

filter by region

Read MostlyA few updates short high < 10 medium

fast/stable

1server/site

1 OLTPsite

Regional updateson one table

Central Publisher

Transactional repl

Updating Subs

Read Mostly

A few updatesmedium high < 10 medium

slow/

unreliab

1

server/site

All

update

Regional updateall tables

Central Publisher

Merge repl

Inserts

(new orders) short high many highfast/stable

1server/site

1

reportsite

Each site only

needs regionaldata

Central Subscriber

Transactional repl

Hot/WarmSpare

Veryshort

high < 2 highfast/stable

1server/site

1 OLTPsite

Fail-overCentral PublisherRemote Distributor

Transactional repl

Read equalEqual updates short high < 10 medium

fast/stable

1server/site

Allupdate

Regional updateall tables

Peer-to-Peer

Transactional

repl

Database Mirroring

Database Mirroring

Database Mirroring


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QuestionsQuestionsIs there any time left????

Send your questions to:[email protected]

[email protected]


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