1. Web Server Administration
Chapter 2
Preparing For Server Installation

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

3. Identifying Server Categories-File Servers
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

4. Identifying Server Categories- Application Servers
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 messages
Its complexity puts more burden on the processor
Servers may also combine the need for fast processors and fast disk subsystems

5. 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 processor

6. 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
Processor
RAM
L2 cache
Bus speed
Pentium 4
Dual Channel RDRAM; PC 133 SDRAM; DDR 200/266 SDRAM
512 K
>400 MHz
Pentium III Xeon
Dual Channel DDR;
SDRAM
up to 2 MB
up to 400 MHz
Celeron
128 K or 256 K
up to 100 MHz

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

8. Evaluating Server Components- UltraSPARC Processors
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 64
66 MHz
UltraSPARC IIi
2 MB 4
UltraSPARC IIe
256 KB

9. 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

10. 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

11. Evaluating Server Components- Selecting a NIC
NIC Type
Speed
Media
Use
Standard
Ethernet
10 Mbps
Twisted pair
(sometimes fiber)
Workstations
Fast
100 Mbps
Workstations and
small to medium
servers
Gigabit
1,000 Mbps
Fiber (sometimes
twisted pair)
High-end servers
10-Gigabit
10,000 Mbps
Fiber
Backbone
connections
ATM
25 Mbps – 622+ Mbps
servers (rare)

12. 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

13. 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

14. 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

15. 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

16. Disk Redundancy through RAID
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

17. 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

18. 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

19. 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 open

20. 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

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

22. Common IP Classes Class First number Subnet mask Number of networks
Number of hosts
Class A
1 – 127
126
>16,000,000
Class B
128 – 191
> 16,000
>65,000
Class C
192 – 223
> 2,000,000
254

23. 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 users on the internal network

24. Summary
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