Web server administration chap02

Identifying Server File ServersCategories- File servers emphasize sending and receiving files  A fast disk subsystem is more important than the processor type  File servers are useful

Web Server Administration

Chapter 2 Preparing For Server Installation

 Identify server categories

 Evaluate server components

 Plan for system disasters and reduce

their effects

 Evaluate network components

 Set up IP addressing

Identifying Server File Servers

Categories- File servers emphasize sending and receiving files

 A fast disk subsystem is more important than the processor type

 File servers are useful in a Web environment when you have a large number of static

HTML pages

 File servers are also appropriate for an FTP server

Identifying Server Application Servers

Categories- Server applications can process requests from many users at a time

 Requires extensive processing power

 A DBMS is a typical example

 Exchange Server does more than send e-mail messages

 Its complexity puts more burden on the processor

 Servers may also combine the need for fast processors and fast disk subsystems

Evaluating Server

Components-Intel Processors

 Most common Intel processor is based on the 386

 32-bit processors

 Data is processed 32 bits at a time

 Uses CISC (Complex Instruction Set

Computer) architecture

 Linux files often end in i386

 These files can be used with all current PCs with the exception of the ones with the Itanium

Evaluating Server

Components-Intel Processors

 Comparing processor speeds across processor versions can be deceiving

 Each newer processor version is much more

efficient at processing data at a given speed

Pentium 4 Dual Channel RDRAM; PC 133

SDRAM; DDR 200/266 SDRAM 512 K >400 MHzPentium III

Xeon Dual Channel DDR; SDRAM up to 2 MB up to 400 MHz

256 K up to 100 MHz

Evaluating Server

Evaluating Server

Components-UltraSPARC Processors

Processor Relative speed Maximum L2

cache Maximum number of

processors

Bus speed

UltraSPARC III Cu Fastest 8 MB over 1000 150 MHz UltraSPARC II About 50% of III Cu 8 MB 64 66 MHz

UltraSPARC IIi About 50% of III Cu 2 MB 4 66 MHz

UltraSPARC IIe About 50% of III Cu 256 KB 4 66 MHz

Evaluating Server

Components-Using Multiple Processors

 BEA WebLogic can assign multiple

server applications to a single processor

in a multi-processor environment

 Processing a single application, such as

a DBMS, spread over multiple

processors is more common

 Applications have to be designed to

take advantage of multiple processors

Evaluating Server

Components-Selecting a Hard Drive Interface

 IDE drives are less capable than SCSI

 Limited ability to add drives

 SCSI can support many drives

 Ultra3, also known as Ultra160, is one

of the most common interfaces used in servers

 Manufactured by Adaptec

Evaluating Server

small to medium servers

10-Gigabit

Ethernet

10,000 Mbps Fiber Backbone

connections

Disaster Planning

 Helps you avoid problems with hardware and software

 A challenge to balance costs with benefits

 In a server, the objective is fault

tolerance

 The ability of a system to keep running even when a component fails

Disaster Assessment and

Recovery

 Determine what can go wrong, what

effects it will have on the organization, and what it will take to fix

 Hardware – determine what will happen

if each component fails

 How to replace failed hardware

 How to restore software (if applicable)

 Who will diagnose hardware problems

Disaster Assessment and

Recovery

 Software disasters are more complex than

hardware disasters

 Could be a combination of application

software and the operating system

 You may be directed to install software that may not work correctly

 Document installation and problems in detail

 Make sure that support is available

System Redundancy

 Often servers and switches have multiple

power supplies so if one fails, the other(s)

can take over

 In case the devices do not have redundancy built in, try to have as much spare hardware

on hand as appropriate for the number of

devices, reliability, and cost

 Also useful are warrantees that allow for

replacement within 24 hours

Disk Redundancy through

RAID

 RAID 1

 Data is duplicated across two drives

 Also called mirroring

 If there are two adapters, it is called duplexing

 RAID 5 (most common)

 Distributes data across a minimum of 3 drives

 If any one of the drives fails, data can be

recovered from the remaining drives

Achieving High Availability

with Multiple Servers

 Many computers act as one

 Can have ten’s of thousands of

computers

 IBM uses computers in a cluster that

serve different purposes

 Microsoft’s approach is to distribute the computing load among distinct servers

Setting Up Backup Systems

 You should maintain a series of backups so you can restore data from a specific date

 Types of backup methods

 Full – all data is backed up

 Differential – backs up all files that are new or

changed since last full backup

 Incremental – backs up all files that are new or changed since the last incremental backup

Backup Considerations

 Back up complete operating system

 On Windows systems, you have to make sure that the Registry is backed up

 Back up special application files

 DBMSs and Exchange keep files open, which

cannot be backed up without special backup

software modules

 Back up data files

 Easy and straightforward unless user has files

Evaluating Network

Components

 Hubs should be avoided in a server

environment

 Increased traffic slows communication

 Switches can come close to the

appearance of a dedicated circuit

between servers

 Routers connect one network to

another

Setting Up IP Addressing

 IP addresses are

divided into the

network portion and

the host portion

 The subnet mask

distinguishes the

two portions

Common IP Classes

Class First number Subnet mask Number of

networks Number of hosts

Class A 1 – 127 255.0.0.0 126 >16,000,000 Class B 128 – 191 255.255.0.0 > 16,000 >65,000 Class C 192 – 223 255.255.255.0 > 2,000,000 254

Network Address Translation

(NAT)

 NAT allows an IP address from one

network to be translated into another address on an internal network

 You can also use NAT to translate a

single IP address valid on the Internet into multiple internal addresses

 Useful if your ISP gives you a single IP

address, yet you have multiple servers and

 File servers and application servers are the

two basic types of servers

 Various families of processors are available

from Intel, Sun, and others

 There are many techniques for minimizing

loss due to hardware and software failures

 Routers and switches allow servers to

communicate

 IP addresses are divided into the network and host portions