Web server administration chap02

Web Server Administration
Chapter 2
Preparing For Server
Installation
1


Overview
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Identify server categories
Evaluate server components
Plan for system disasters and reduce
their effects
Evaluate network components
Set up IP addressing

2


Identifying Server
Categories-File Servers
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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
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Identifying Server
CategoriesApplication
Servers
Server applications can process requests
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from many users at a time
Requires extensive processing power
A DBMS is a typical example
Exchange Server does more than send email messages

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Its complexity puts more burden on the
processor

Servers may also combine the need for
fast processors and fast disk subsystems
4


Evaluating Server
ComponentsIntel Processors
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Most common Intel processor is based
on the 386
32-bit processors
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Data is processed 32 bits at a time

Uses CISC (Complex Instruction Set

Computer) architecture
Linux files often end in i386
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These files can be used with all current PCs
with the exception of the ones with the
Itanium processor
5


Evaluating Server
ComponentsIntel Processors


Comparing processor speeds across
processor versions can be deceiving
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Each newer processor version is much more
efficient at processing data at a given speed

Processor

RAM

L2 cache

Bus speed

Pentium 4

Dual Channel RDRAM; PC 133
SDRAM; DDR 200/266 SDRAM

512 K

>400 MHz

Pentium III Dual Channel DDR;
Xeon
SDRAM

up to 2 MB

up to 400
MHz

Celeron

128 K or
256 K

up to 100
MHz

SDRAM

6

Evaluating Server
ComponentsUltraSPARC Processors
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Manufactured by Sun
Only used in computers from Sun
64-bit processors
Uses RISC (Reduced Instruction Set
Computer) architecture

7


Evaluating Server
ComponentsUltraSPARC Processors
Processor

Relative speed

Maximum L2 Maximum
cache
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

8


Evaluating Server
ComponentsUsing Multiple Processors
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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

9

Evaluating Server
ComponentsSelecting a Hard Drive
 IDE drives are less capable than SCSI
Interface

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
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10


Evaluating Server
ComponentsSelecting a NIC

NIC Type

Speed

Media

Use

Standard
Ethernet

10 Mbps

Twisted pair
(sometimes fiber)

Workstations

Fast
Ethernet

100 Mbps

Twisted pair
(sometimes fiber)

Workstations
and
small to
medium
servers

Gigabit
Ethernet

1,000 Mbps

Fiber (sometimes
twisted pair)

High-end
servers

10-Gigabit
Ethernet

10,000 Mbps

Fiber

Backbone
connections

ATM

25 Mbps –
622+ Mbps

Fiber

Workstations
and
servers (rare) 11


Disaster Planning

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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

12


Disaster Assessment and
Recovery
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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
13

Disaster Assessment and
Recovery
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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
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Document installation and problems in
detail
Make sure that support is available
14


System Redundancy
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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
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Also useful are warrantees that allow for
replacement within 24 hours

15


Disk Redundancy through
RAID
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RAID 1
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Data is duplicated across two drives
Also called mirroring
If there are two adapters, it is called duplexing

RAID 5 (most common)
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Distributes data across a minimum of 3 drives
If any one of the drives fails, data can be
recovered from the remaining drives

16


Achieving High Availability
with Multiple Servers
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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

17

Setting Up Backup
Systems
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You should maintain a series of backups
so you can restore data from a specific
date
Types of backup methods
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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
18


Backup Considerations
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Back up complete operating system
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Back up special application files
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On Windows systems, you have to make
sure that the Registry is backed up
DBMSs and Exchange keep files open, which
cannot be backed up without special backup
software modules

Back up data files
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Easy and straightforward unless user has
files open
19


Evaluating Network
Components
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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

20


Setting Up IP Addressing
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IP addresses are
divided into the
network portion
and the host
portion
The subnet mask
distinguishes the
two portions

21


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

22


Network Address
Translation
(NAT)
NAT allows an IP address from one
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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 users on the internal

network
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Summary
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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
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