SQL Server High Availability

SQL Saturday 2009 – Portland, Oregon
HA cover

Copyright 2009 – Database Architechs
www.dbarchitechs.com

Paul Bertucci
• Founder Database Architechs – www.dbarchitechs.com
– Specializing in HA, Database Design, Data Architecture, Data Replication, and P&T for SQL
Server, Sybase, DB2 and Oracle
– Over 28+ years experience in Data Base industry
• Co-Author of SQL Server 2000 Unleashed! (SAMS)
• Co-Author of SQL Server 2005 Unleashed! (SAMS)
• Co-Author of SQL Server 2008 Unleashed! (SAMS) – Summer 2009 !
• Co-Author of ADO.NET in 24 hours (SAMS)
• Author MS SQL Server High Availability (SAMS)
• Author Sybase Performance & Tuning
• Author Sybase Physical DB Design
• Veritas SQL Server Performance Series
• Former Chief Data Architect Symantec Corporation
• Current Chief Architect Autodesk Corporation

pbertucci@dbarchitechs.com


Agenda
What is High Availability?

How do you assess your HA Requirements?

What are the MS SQL Server related options for HA?

How each option delivers HA…

Performance and Tuning is critical too – SQL Shot!

Q&A

Test

1. What is the quickest way to test if your SQL Server Clustering
configuration is failing over properly?

2. What is the SQL Server feature in SQL Server 2005/2008
that replaces Log Shipping?


What is Availability?
Application
Availability

Failure causes:
Planned Unplanned - Human
Uptime - Hardware
Downtime Downtime - Software

Recoverable Disaster


The cost of Un-Availability
Airline Reservation Systems - $67K to $112K per hour

ATM Service Fees - $12K to $17K per hour

Brokerage (Retail) - $5.6M to $7.3M per hour

What is your cost of downtime?


Across all layers of your systems
Network
Application
Middleware
Database
HARDWARE
Operating System Network Components
Servers
Disk Systems
Memory


Availability across planned operation

100%
Availability Goals

90%
Availability (%)

Feb 14-28 Mar 1 – Apr 15 Apr 16 – 20

Starting Date Date of Failure Days Hours Minutes MBU (minutes) TU Avail %
Period 1 2/14/2008 2/28/2008 15.00 24.00 60.00 21600.00 38.00 99.82407
Period 2 3/1/2008 4/15/2008 46.00 24.00 60.00 66240.00 68.00 99.89734
Period 3 4/16/2008 4/20/2008 5.00 24.00 60.00 7200.00 442.00 93.86111

Overall 2/14/2008 4/20/2008 66.00 24.00 60.00 95040.00 548.00 99.4234

Availability Continuum
Characteristic Availability Range

Extreme Availability Near zero downtime! (99.5% - 100%)

High Availability Minimal downtime (95% - 99.4%)

Standard Availability With some downtime (83% - 94%)
tolerance

Acceptable Availability Non-critical Applications (70%-82%)

Marginal Availability Non-production Applications (up to 69%)

Availability Range describes the percentage of time relative to the “planned” hours of operations

8,760 hours/year | 168 hours/week | 24 hours/day
525,600 minutes/year | 7,200 minutes/week | 1,440 minutes/day

Applications and Availability Extreme Availability
High Availability ATM
Zero Standard Availability
Planned eCommerce 911
Downtime email
Acceptable Availability
Inventory
Accounting Mgmt
Marginal Availability
HR

Marketing
Mailers

Zero
Unplanned
Downtime
Five 9’s (99.999%) ~ 6 minutes/year downtime

What do you need?
It’s as simple as 1, 2, 3 +

Step One – Launch of a brief “Phase 0” HA Assessment

Step Two – Complete an HA Primary Variables gauge

Step Three – Match your need to the optimal HA solution

Step + (optional) – Determine the ROI of the HA solution


Assessing HA with Primary Variables
0% 100%
Uptime Requirement
Long Short
Time to Recover
High Low
Tolerance of Recovery Time
Low High
Data Resiliency
Low High
Application Resiliency
Low High
Degree of Distributed Access/Synchronization
Often Never
Scheduled Maintenance Frequency
Low High
Performance/Scalability
Low High
Cost of Downtime ($$ lost/hr)
Low High
Cost of the High Availability Solution ($$)

Development Methodology
“With High Availability built in”
Assessment
Assessment
(scope)
(scope) 3. Code & Test
- Code Development/Unit Testing
- Fully integrate the HA solution with the application
0. Assessment Requirements
Requirements 4. System Test & Acceptance
- Project Planning - Full system Test/User Acceptance
- Project Sizing - Full HA Test/Validation/Acceptance
- Deliverables Identified (SOW)
- Schedules/milestones
Design
Design 5. Implementation
- Production Build/Implementation
- High-Level Requirements (scope)
- Production HA build/monitoring begins
- Estimate HA Primary Variables (gauges)

1. Requirements Code & Test
Code & Test
- Detail Requirements (process/data/technology)
- Early Prototyping (optional)
- Detailed HA Primary Variables System Test &
System Test &
- Detailed Service Level Agreements/Rqmts Acceptance
- Detailed Disaster Recovery requirements
Acceptance

2. Design Implementation
Implementation
- Detail Design (data/process/technology)
- Choose and design the matching HA
solution for the application Copyright 2009 – Database Architechs

Spiral/Rapid Methodology
Iterative approach 0. Initial assessment
- Project Planning
7. Implementation - Project Sizing
- Production Build/Implementation - Deliverables Identified (SOW)
- Production HA build/monitoring begins - Schedules/milestones
- High-Level Functions (scope)
Transition Inception -Estimate HA Primary
Variables (gauges)

3. Requirements
6. System Test & Acceptance - Detail Requirements
- Full system Test/User (process/data/technology)
Acceptance - Detail HA Primary Variables
-Full HA Test/Validation - Detailed SLA/Rqmts
/Acceptance - Detailed Disaster
Recovery requirements

5. Code & Test 1. High-level Rqmts/Prototyping
- Code Development/Unit Testing - High-level requirements
-Fully integrate the HA solution (process/data/technology)
with the application - High-level HA Primary Variables
Construction Elaboration/Prototype
2. Early Code & Test 4. Design
- Early code and testing of apps/DI - Detail Designs (process/data/technology)
(process/data/technology) Copyright 2009 – Database Architechs - Choose and design the matching HA solution
- Prototyping of HA options www.dbarchitechs.com for the application (verified via prototypes)

Valid High Availability Options

Disk Other Cluster Data SQL DB Log
Methods HW Services Replication Clustering Mirroring Shipping

Disk
Methods

Other
HW

Cluster
Services

Data
Replication

SQL
Clustering

DB
Mirroring

Log
Shipping Copyright 2009 – Database Architechs

MSCS Cluster Services

C:
Local
Binaries
Windows 2003
Node A Enterprise Edition Cluster Group
Resources
D:

Shared
SCSI
Disk

Q: Quorum

Windows 2003
Node B Enterprise Edition C:
Copyright 2009 – Database Architechs Local
www.dbarchitechs.com Binaries

SQL
SQL Clustering
Connections COLTST1
C:
Local
Binaries
Windows 2003
Enterprise Edition Cluster Group
Resources
SQL Server 2008 (physical)
E: MS DTC

Master DB
SQL Server 2008 SCSI TempDB
(Virtual SQL Server) Appl 1 DB
VSQLDBARCHVSQLSRV1
Q: Quorum
Disk
SQL Server 2008 (physical) SQL Agent

Windows 2003 COLTST2
Enterprise Edition C:
Copyright 2009 – Database Architechs Local
www.dbarchitechs.com Binaries

Data Replication
Can be used as a Warm Standby
and/or for Reporting needs
“Primary”
SQL Server 2008
“Replicate”
SQL Server 2008
Publication Subscription
Adventure Server
Server
Works AdventureWorks

Distribution
Server distribution
“Replicate”
SQL Server 2008
SQL Server 2008 Subscription
Server
Central Publisher/ AdventureWorks

Remote Distributor
Replication model

Database Mirroring
Client Client Client Client

Network

A

SQL Server 2008 SQL Server 2008
Database Mirror Server

MirroringAdventure
Principal
Works DB
D Adventure
D
Server B Works DB
translog translog
C

SQL Server 2008

Witness
MSDB DB
Server

Database Mirroring
with DB Snapshots
Mirror Server
20FIG34 AdventureWorks AdventureWorks
Principal
DB DB
Server
translog translog
Database Snapshot

SQL Server 2008

rk
rk

s
oo
Witness

er
tw
tw

Us
MSDB DB

Ne
Server

Ne

ng
rti
po
Re

Log Shipping
“Source”
SQL Server 2008 “Destination”
SQL Server 2008
TxnLog
Primary CallOne DB backups Secondary
Server Server
translog
CallOne DB
BackupCallOne_tlog_200405141120.TRN
Last log shipped
Delay Answer

LogShareCallOne_tlog_200405141120.TRN TxnLog
TxnLog
Copies Restores
“Monitor”
SQL Server 2008 Delay between
logs loaded
Delay Answer
Monitor
MSDB DB
Server


RAID Disk I/O Summary

RAID Level Fault Tolerance Logical Physical I/Os Logical Physical
Reads per Writes I/Os per Write
Read
RAID 0 None 1 1 1 1

RAID 1 or 10 Best 1 1 1 2 writes
(Optimal for OLTP)

RAID 5 Moderate 1 1 1 2 reads + 2 writes
(Optimal for mostly (that’s 4 per write!)
READ ONLY
systems)

NOTE:
Several RAID vendors are now showing RAID 5 and RAID 10
performance almost equivalent now via Cache/Buffer
advancements on their RAID controllers

Fault Tolerance and SQL DB Files
Description Fault Tolerance
Quorum Drive The quorum drive used with MSCS should be RAID 1 or
isolated to a drive by itself (very often mirrored RAID 10
as well for maximum availability)
SQL Server For OLTP (online transaction processing) systems, RAID 10
Database the database data/index files should be placed
files (OLTP) on a RAID 10 disk system.

SQL Server For DSS (Decision Support Systems) systems that RAID 5
Database are primarily READ ONLY, the database
files (DSS) data/index files should be placed on a RAID 5
disk system.
Temp DB Highly volatile disk I/O (when not able to do all it’s RAID 10
work in cache)
SQL Server The SQL transaction log files should be on their own RAID 10
Transaction mirrored volume for both performance and Or
Log files database protection. (for DSS systems, this RAID 1
could be RAID 5 also).

Example DB data files configuration
E:
RAID 5
Master DB
log
DSS - DB F:
(read only)

TempDB
RAID 10
log
G:
OLTP X - DB

log
OLTP Y - DB H:

RAID 1 or
RAID 10

Q: Quorum

Decision Tree approach

Condition/Question
Case A Case B Case C Case D . . . Case n
Action Action Action Action . . . Action
V W X Y Z

Disk Other Cluster Data SQL Database Log Distributed
Methods HW Services Replication Clustering Mirroring Shipping Transactions
Database Snapshots

Decision-Tree Path Traversal

SQL
Clustering Database
Cluster Snapshots
Services
1a2c3 1a2d3
1a2e3
1a2b3 Database
b c d Mirroring
a 1a2 e
1a2a3

HA
a b 1b2
1e2
e 1 c
Not Needed d
1c2 Log
1d2 Shipping

HW/Disk
Redundancy Data
Distributed Replication
Transactions

Decision-Tree: ASP Questions 1-3
1
What % of availability must your application have?
A% <= 70% 70% < A% < =83% 83 < A% < =95% 95% < A% < =99.5% A%> 99.5%

Marginal Acceptable Standard High Extreme
Availability Availability Availability Availability Availability

2
How much tolerance of downtime by end-users?
Very High High Medium Low Very Low

Not Low Standard High Extremely
Critical Criticality Criticality Criticality Critical

3
What is the per hour cost of downtime for this application?
$C<= $3K $3K < $C < =$7K $7K < $C < =$12K $12K < $C < =$20K $C > $20K

Very Low Low Moderate High Very High
Cost Cost Cost Cost Cost

4
How long does it take to get the application back online?
Very Long Long Average Short Very Short

Marginal Acceptable Standard Fast Extreme
Recoverability Recoverability Recoverability Recoverability Recoverability

5
How much of the application is distributed?
None A Little Medium A Lot All

Non- Low Moderately High Extremely
Distributed Distribution Distributed Distribution Distributed

6
How much data inconsistency can be tolerated?
Very Little A Little Medium A Lot Very Much

Very High High Moderate Low Minimal
Consistency Consistency Consistency Consistency Consistency

7
How often is scheduled maintenance required?
Very Often Often Average Not Often Rarely

Very High High Reasonable Low Minimal
Downtime Downtime Downtime Downtime Downtime

8
How important is high performance and scalability?
Not Very Somewhat Moderately Very Much Extremely

Very low Low Reasonable High Extreme
Performance Performance Performance Performance Performance

9
How important is the application connection to the end-user?
Not Very Somewhat Moderately Very Much Extremely

Connection Connection Connection
Not Establish new
Re-established Retry process Fail-over
Needed Connection easily

Decision-Tree: ASP Question 10
10
What is the estimated cost of the HA Solution (budget)?
C$ < $10K $10K <= C$ < $100K $100K <= C$ < $250K $250K <= C$ < $500K C$ >= $500K

Very Low Low Moderate High Extreme
Cost Cost Cost Cost Cost

1. 1e Extreme Availability goal
2. 1e+2d Very low tolerance of downtime
3. 1e+2d+3e $15k/hr cost of downtime (High Cost)
4. 1e+2d+3e+4c Average recovery time
5. 1e+2d+3e+4c+5a No distributed components or synchronization
6. 1e+2d+3e+4c+5a+6b A little data inconsistency can be tolerated
7. 1e+2d+3e+4c+5a+6b+7c Average amount of scheduled downtime
8. 1e+2d+3e+4c+5a+6b+7c+8d Performance is very much important
9. 1e+2d+3e+4c+5a+6b+7c+8d+9b Connection can be re-established
10. 1e+2d+3e+4c+5a+6b+7c+8d+9b+10c Moderate HA Cost/Good budget

Best fitting HA Solution (together)

Disk Other Cluster SQL
Methods HW Services
www.dbarchitechs.com Clustering

Basic “one-two” Punch approach

1 Build the proper foundation first

Hardware/Network Disk Backups Vendor Training, QA, Software
Redundancy DB Backups SLA’s & Standards Upgrades

Then, build within the appropriate HA solution
2
that your application requires

Disk Other Cluster Data SQL Database Log Distributed
Methods HW Services Replication Clustering Mirroring Shipping Transactions

Database Snapshots


ASP – Scenario #1 with SQL Clustering
ASPProd1
C:
Local
Binaries
Windows 2003 MSCS
Enterprise Edition Cluster Group
Resources
JRUN/WebServices/IIS

SQL Server 2005 (physical)
Master DB
E:
Network

TempDB
SQL Server 2005 SCSI F:
(Virtual SQL Server)
ASQLASPSERV1 HOE DB
G:
MS DTC
Q: Quorum
SQL Server 2005 (physical) SQL Agent
Disk
Windows 2003
Enterprise Edition MSCS C:
ASPProd2
Active/Passive Copyright 2009 – Database Architechs Local
Binaries
Configuration www.dbarchitechs.com

Log Shipping
“Source”
SQL Server 2000 “Destination”
SQL Server 2000
TxnLog
Primary CallOne DB backups Secondary
Server Server
translog
CallOne DB
BackupCallOne_tlog_200405141120.TRN
Last log shipped
Delay Answer

LogShareCallOne_tlog_200405141120.TRN TxnLog
TxnLog
Copies Restores
“Monitor”
SQL Server 2000 Delay between
logs loaded
Delay Answer
Monitor
MSDB DB
Server


North America
(Reporting & “warm/hot” spare)
SQL Server 2000
Headquarters (Santa Clara) Subscription
SQL Server 2000 Server
Live REPL MktgDB
Publication
solution
Server MktgDB
Europe (Reporting)
SQL Server 2000
Subscription
Distribution Server
Server distribution MktgDB

SQL Server 2000
Far East (Reporting)
SQL Server 2000
Central Publisher/ Subscription
Remote Distributor Server
Replication model MktgDB

SQL Server 2000
Central Publisher SQL Server 2000
Subscription (default option) Subscription
Server Server
Northwind SQL Server 2000 Northwind

Publication
Server Northwind

Distribution
Server distribution

Oracle SQL Server 7.0
Subscription Subscription
Server Server
Northwind Northwind

Central Publisher
Subscription Remote Distributor Subscription
Server Server
Northwind SQL Server 2000 Northwind

Publication
Server Northwind

Distribution
Server distribution

SQL Server 2000

Oracle SQL Server 7.0
Subscription Subscription
Server Server
Northwind Northwind

Data Access Latency Autonomy
Distributing Data
Sites
(locations)
Frequency Network Machines Owner Other REPLICATION

Read Only Each site only Central Publisher
short high many high fast/ 1 1 OLTP needs regional Transactional repl
Reporting stable server/site
Database Mirroring site data filter by region

Read Only Each site only Central Publisher
fast/ 1 Snapshot repl
Reporting long high many low 1 OLTP needs regional
stable server/site
Database Mirroring site data filter by region

Read Mostly Regional updates Central Publisher
fast/ 1 Transactional repl
A few updates short high < 10 medium 1 OLTP on one table
stable server/site site Updating Subs

Read Mostly Regional update Central Publisher
slow/ 1 All Merge repl
A few updates medium high < 10 medium
unreliab server/site update
all tables

Read equal Regional update Peer-to-Peer
fast/ 1 All Transactional
Equal updates short high < 10 medium all tables
stable server/site update repl

Inserts 1 Each site only Central Subscriber
short high many high fast/ 1 Transactional repl
(new orders) report needs regional
stable server/site data
site

Central Publisher
Hot/Warm Very fast/ 1 Fail-over Remote Distributor
high <2 high 1 OLTP
Spare short stable server/site Transactional repl
site
Database Mirroring

Foundation, Foundation, Foundation
Piecing it together
Hardware/Network Disk Backups Vendor Training, QA, Software
Redundancy DB Backups SLA’s & Standards Upgrades

Network
Application
Middleware
Database
HARDWARE
Operating Network Components
System Servers
Disk Systems
ck Memory
Sta
ystem
S Copyright 2009 – Database Architechs

ROI
Calculati
on


Database Mirroring

Transparent Client Redirect
Network

A


Mirror Server
Principal Applx DB D
Applx DB D
Server B
translog translog

C

“Copy-on-Write” technology
SQL Server 2008

Witness
MSDB DB
Server

20FIG30

SQL Server 2005 Database Mirroring

20FIG31
SQL Server 2008 Database Mirroring

Database Mirroring with
DB Snapshot

Mirror Server
Principal Applx DB
Applx DB
Server
translog translog
Database Snapshot

SQL Server 2005

rk
rk

s
oo
Witness

er
tw
tw

Us
MSDB DB

Ne
Server

Ne

ng
rti
po
Re

Snapshot
Source Data Users
Pages
SELECT …..data…….
FROM AdventureWorks
SNAPSHOT
04
SQL Server 2008

SQL
Server
Snapshot
AdventureWorks AdventureWorks
DB DB

System Catalog Sparse
of changed pages File
Pages

Instance: SQL2008xyz PH Topology With Snapshots
Endpoint Name: “endpoint4mirroring”
Role: PARTNER Critical
Report

Network
Network
Users
SQL Server 2008

Principal Instance: SQL2008zzz
Endpoint Name: “endpoint4mirroring”
Server
Role: PARTNER
SQL Server 2008
OLTP Application

Active Mirror Server
Clustered
Replication

Adventure Adventure
Works DB Works DB

translog translog
Database
Passive Snapshot

PH Topology Network
Network
Principal
Server

SQL Server 2008
Less Critical
Reporting Users

Publisher The Combo Pack

Principal Mirror SQL Server 2008

Server Server
Subscriber

Distributor

Principal Mirror
Server Server
SQL Server 2008

SQL Server 2008
Witness
Server
Subscriber


Restart
Stage

Rolled Forward
time
Transactions
SQL Server
SQL Server 2000 2005/2008

SQL SQL
Server Server

Transactions
Rolled Back
SQL Server 2005/2008
database is available
SQL Server 2000
database is available
complete
Restart

DB Availability
Improvement !

Performance and Tuning
counts in HA
SQL SHOT – MS SQL Server

Questions

Is there any time left????


SQL Server Resources

Stop!

Fail-Over via Move Group

ANSWER to question #1

Distributed Transactions

“Primary Location”
SQL Server 2000

Try primary first
Reads Northwind 1

If
no
ta
va
ila
ble
, try “Secondary Location”
MS DTC

sec SQL Server 2000
on
Updates da
ry
Northwind 2
Must succeed
together, or be
both rolled back
(two-phase commit)

SQL Server High Availability

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Andere mochten auch

Andere mochten auch (20)

Ähnlich wie SQL Server High Availability

Ähnlich wie SQL Server High Availability (20)

Mehr von Database Architechs

Mehr von Database Architechs (14)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

SQL Server High Availability