Transcript Web Server Administration

Web Server Administration
Chapter 2
Preparing For Server Installation
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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
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Identifying Server CategoriesFile 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
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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
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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
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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
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Evaluating Server ComponentsIntel Processors
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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
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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
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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
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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
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Evaluating Server ComponentsSelecting a Hard Drive Interface
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IDE drives are less capable than SCSI
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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
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Manufactured by Adaptec
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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)
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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
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The ability of a system to keep running even
when a component fails
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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
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How to replace failed hardware
How to restore software (if applicable)
Who will diagnose hardware problems
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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
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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
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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
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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
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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
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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
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Evaluating Network
Components
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Hubs should be avoided in a server
environment
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Increased traffic slows communication
Switches can come close to the
appearance of a dedicated circuit
between servers
Routers connect one network to
another
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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
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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
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Network Address Translation
(NAT)
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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
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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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