Chapter 2: Designing Physical Storage MCITP Administrator: Microsoft SQL Server 2005 Database Server Infrastructure Design Study Guide (70-443)

Chapter 2: Designing Physical Storage

MCITP Administrator: Microsoft SQL Server 2005 Database Server

Infrastructure Design Study Guide (70-443)

Types of Files

• Primary Data files (.mdf)

• Secondary Data files (.ndf)

• Transaction log files (.ldf)

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Filegrpoups

• Logical groupings of secondary data files

• Useful for VLDBs


Pages

• Smallest unoit of storage in a SQL Server Data File

• 8192 bytes each

• Start with 96 byte header


Types of Pages

• Data

• Text/Image

• Index

• Global Allocation Map

• Index Allocation Map

• Page Free Space


Extents

• Collection of eight contiguous pages

• Two types of extents:– Uniform– Mixed


Estimating Database Size

1. Calculate record size of table by adding the size if each column

2. Divide 8096 by row size, rounding down to nearest number

3. Divide number of rows you expect by by result from step #2. Round down

4. Multiply results from step 23 by 8192

5. Result is number of bytes tour table will take up on the disk


RAID

• RAID-0 or disk striping

• RAID-1 or disk mirroring

• RAID-5 or stripe set with parity

• RAID-10 combination of RAID-1 and RAID-5


Designing Transaction Log Storgae

• Transaction log records all transactions and database modifications made by each transaction.

• Can be used to return database to consistent state

• Should not be deleted or removed without full understanding of effects


Transaction Log Operations

• Recover individual transactions

• Recover ll incomplete transactions when QL Server is started

• Rolling back a restored database, file, filegroup or page forward

• Support transactional replication

• Supprot standby server solutions


Truncating Transaction Log

• Can be set as a property

• Does not reduce size of physical log file

• Logs automatically truncated under Simple Recovery Model

• Logs must be specifically backed up under Full and Bulk-logged recovery models


Monitor Log Space Usage

• Monitor log space usage using the command DBCC SQLPERF (LOGSPACE)

• You can also use sys.database_files to determine current size as well other options and porperties for a log file.


Shrinking Log File

• Truncating does no reduce physical size of log file

• Shrinking removes one or more inactive virtual log files


Adding or Enlarging Log File

• Adding or enlarging a log file is a way to gain space without shrinking

• Adequate available disk space needs to be available

• To add, use ADD LOG FILE clause of ALTER DATABASE command

• To enlarge, use MODIFY FILE clause of ALTER DATABASE statement, specifying SIZE and MAXSIZE syntax


Transaction Log Storage

• Store transaction logs and data files on separate disk volumes

• Locate transaction log files on drives supporting sequential write operations

• Store data files on drives supporting random read and write operations

• Use fault tolerant storage• Make multiple backup copies of

transaction log• Bakup up to separate device such as a

tape or separate disk


Back-up File Storage

• SQL Serrver only allows placing of active files to what it deems to be a local hard disk.

• Local hard disks are either on the local machine or on a hardware device connected directly to SQL Server machine

• This limitation does not apply to backups.


Backup Management – Best Practices

• Complete history of backup is stored in msdb database

• Store backups in secure place• Label backup media. Include expiration

dates• Jeep older backups for a designated

period of time in case of damage or loss to current backup

• Consider using RAID-10• Write to disks attached to local machine

to improve speed


Maintaining Transaction Log Backups

• Three types of Transaction log backup:– Pure Log Backup– Bulk Log Backup– Tail Log Backup


Deciding Where to Install Operating System

• Install OS on a partition separate from data and applications

• Place OS on a separate partition with or without SQL Server executables. Partition should also host paging file.

• Do not use file encryption or compression since they are IO intensive and provide no benefit to SQL Server, but can reduce performance


Where to Place SQL Server Service Executables

• Only install services you plan to use• SQL Server and SQL Server Agent run as

a Microsoft Windows services• Must be assigned a Windows user

account• Programs and data files can’t be installed

on – Removable disk drive– Compressed volume– Shared drives ina failover cluster instance


Number & Placement of Files for Each Database

• Location of all files in a database are recorded in the primary file of the database and the master database

• Master database is primary source• Primary file used to specify location when:

– Using CREATE DATABASE– Upgrading from SQL Server 2000 or SQL

Server 7.0 to SQL Server 2005– Restoring master database


Filenames

• Logical_file_name is used to refer to tehe physical file in all Transact-SQL statements

• OS_file_name is the name of the physical file, including the directory path


Setting File Size

• Files can grow beyond specified start size

• Growth is based on sepcified growth increment

• Maximum file size can be set


Setting up Filegroups

• Two types of filegroups– Primary filegroup– User defined filegroups

• One filegroup in each database is designated the default filegroup. If none is designated the primary filegroup serves as the default filegroup


Designing Instances

• Two types of SQL Server 2005 instances:– Default– Named


Designing Instances – Guidelines

• If upgrading from SQL Server 7.0 the upgraded instance must be a default instance.

• If only one instance is planned it should be a default instance

• If supporting slinet connectiosn from SQL server 7.0 use a default instance

• Any application installing SQL Servr Express Edition should do so as a named instance

• Instances can be installed at any time


Deciding on number of instances

• Determined by available resources

• Typically one SQL Server instance will outperform two or more instances on same hardware

• Use multiple instances to isolate databases on a server


Instances per SQL Server Edition and Component

SQL Server 2005 edition

Database Engine instances

Analysis Services instances

Reporting Services instances

Enterprise Edition, Developer Edition

50 50 50

Standard Edition, Workgroup Edition, Express Edition

16 16 16


Naming instances

• Limited to 16 characters• Names are case insensitive• Once named, an instance cannot be

renamed• Can’t contain default, MSSQLServer or

other reserved keywords• First character must be letter or

underscore• Embedded space or other special

characters aren’t allowed• Cannot include \ : ; ‘ & @ or ,


How Many Physical Servers?

• How busy is each database

• What is the size of the database in relation to available disk space

• What is the total load on the server


System Databases

Database Database file Log file

masterMaster.mdf Mastlog.ldf

modelModel.mdf Modellog.ldf

MsdbMsdbdata.mdf Msdblog.ldf

tempdbTempdb.mdf Templog.ldf

When an instance of SQL Server is installed, Setup creates the database and log files as shown below:


Deciding Where to Place System Databases

• Normally left in the default installation directory

• May need to be moved due to:– Failure recovery– Planned relocation– Relocation for scheduled disk

maintenance


Physical Storage for tempdb Database

• Size and physical placement can effect performance

• Optimal size and location determined by many factors, including workload, installed components, etc.

• No hard and fast rule


Physical Storage for tempdb Database - Guidelines

• Place tempdb on fast I/O disk subsystem

• Use disk striping

• Avoid placing on same disk as user database


Optimizing Configuration of tempdb

• Set recovery model to Simple

• Set file to automatically grow

• Set growth increment to a reasonable level

• Preallocate space for tempdb by setting large initial file size

• Create one tempdb data file per CPU


Establishing Service Requirements

• Install only Services needed, disabling others not in use

• Don’t install SQL Server on a domain controller

• Run separate SQL Server services under separate Windows accounts

• If multitier environment run Web logic and business logic on separate computers


Specifying Instance Configurations

• Configuration Manger tool can be used to – Manage services– Change accounts used by services– Configure network protocols– Manage network connectivity

configuration

for each instance


Documents

Chapter 2: Designing Physical Storage MCITP Administrator: Microsoft SQL Server 2005 Database Server Infrastructure Design Study Guide (70-443)