Post on 22-Dec-2015
transcript
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Web Server Administration
Chapter 2Preparing For Server
Installation
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Overview
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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Server Categories
What do you use the server for? File Server
High-speed disk drivers Application Server
High-speed processors
Depending on the server type we choose our hardware and software
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Identifying Server Categories-File Servers
File servers emphasize on 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 Categories-Application Servers Application Servers can process requests from
many users at a time Require extensive processing power A DBMS is a typical example Many contain dynamic HTML and scripting Many email servers are considered as
Application Servers 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
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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
Pentium 4 with Clock speed: 3.4 GHz Number of transistors: 55 million
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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 SDRAM 128 K or 256 K
up to 100 MHz
Number of transistors? http://www.raptureready.com/time/rap31d.html
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Evaluating Server Components-UltraSPARC Processors
Manufactured by Sun Only used in computers from Sun 64-bit processors Uses RISC (Reduced Instruction Set
Computer) architecture More efficient than CISC
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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
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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
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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
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Selecting a Hard Drive Reliability
MTBF (Mean Time Between Failure) Capacity Data Transfer Rate
Buffer to HD / HD to buffer Average Seek Time Rotational Speed
How fast the disk spins (7 Krps) Access Time
How long to retrieve the information. Includes the seek time
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Evaluating Server Components-Selecting I/O Ports Video
PCI External and can be connected to the NIC PCI bus is a 32-bit burst with a maximum rate of 132 MB/s PCI-X is 64-bit wide and has a BW of 500 MB/s
AGP High-speed graphic adaptor Connected to the main memory It is not a bus it can be connected to one device only Has a BW of about 1 GB/s to the memory AGP 2.0 can go up to 3.0 GB/s in BW
Legacy ISA bus; low speed
For more information check my web:
http://www.ccsu.edu/technology/farahmand/bhcosc/teaching.htm (3523)
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Evaluating Server Components-Selecting 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
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
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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
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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
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Recovery Plans
HD Failure SW Failure Electrical Problems System Redundancy Availability (clusters)
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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
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Disk Redundancy through RAID RAID 1
Data is duplicated across two drives Also called mirroring If there are two adapters, it is called disk
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
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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
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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
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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
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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
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Setting Up IP Addressing 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) 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
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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