Now that we've discussed NICs and some of the connectivity devices you will run into when you network computers, we will finish out the chapter by looking at some other critical pieces of PC hardwarespecifically, motherboards, processors, hard drives , and RAM. We need to discuss these hardware components because they inherently affect a PC's overall performance. Understanding how these hardware components fit into the overall PC hardware puzzle will help you when it is time for you to select hardware for network clients or network servers. Since this book serves as a primer to networking and network hardware, you should consult a heavy-duty reference such as Upgrading and Repairing PCs by Scott Mueller, published by Que.
First, let's take a look at some issues related to motherboards. Then we can take a look at processors, hard drives, and memory.
The motherboard is the main system board for a PC, and it provides the data highway (or bus system ) that moves data between components on the motherboard and the PC's processor. The speed of data moving along the bus is measured in megahertz (MHz). Although 66MHz was once considered fast for the bus speed of a motherboard, motherboard manufacturers quickly provided motherboards with bus speeds of a 100 to 133MHz. Motherboard bus speed has continued to increase with each new motherboard and chip set. There are motherboards now available that provide bus speeds in excess of 500MHz.
At one time the motherboard would never have been considered the limiting factor in a PC configuration but with advances in PC memory and processors, a computer with an older motherboard may only provide few options as far as upgrading; meaning newer memory modules and processors may not be compatible with a legacy motherboard.
Although how fast a computer can work with data is really ultimately decided by the computer's processor, deciding on a particular motherboard should probably be determined, in part, by the features the motherboard's chipset provides. The chipset determines the ceiling for the bus speed. Chipsets provide DMA support (discussed earlier in this chapter in the section "Selecting a NIC") and other features, such as an Accelerated Graphics Port (AGP provides faster video response). These features will also boost the overall performance of the computer.
The processor is really the brain of the computer. It processes binary information input by the user or received from other devices on the computer, such as the network interface card. Processor speed is measured in megahertz (MHz). The Intel processor used on the original IBM PC ran at 8MHz. Processors are now available that run in excess of 2,000MHz (that is, 2GHz or gigahertz ).
Processors are manufactured by a number of different companies, including Intel, Motorola, Cyrix, and AMD. The selection of the processor type and speed, as far as networking is concerned , will depend on whether you are configuring a client machine or a network server. Faster (and even multiple) processors are a must on a server that needs to process a large number of calls for data from users on the network.
Basically, you should choose the processor you want to use for a computer and allow that choice to determine the motherboard you use for the computer. This helps narrow the choice of motherboards down to those that support the processor.
There seems to be as many memory types for personal computers as there are types of apples. Computer memory or RAM (Random Access Memory) is the working storage area. It is used by the processor and other devices to temporarily store information, and it's also accessed by software as we work on our computers.
You can't just install any type of RAM on your motherboard; it is actually dictated by the chipset the manufacturer places on the motherboard. This means you need to know the type of RAM that is compatible with a particular motherboard.
RAM comes in two basic formats: SIMMS and DIMMS. A SIMM (Single Inline Memory Module) is a epoxy -coated silicon wafer that contains a number of memory chips. The SIMM fits into a slot on the motherboard. SIMMs must be placed on the motherboard in identical pairs (there are typically four SIMM slots on a motherboard). This means that to have 64MB of memory on the motherboard, two 32MB SIMMs would be installed. You will only run into SIMMs if you are working with an older computer that has a legacy motherboard. Newer motherboards support the DIMM.
A (DIMM) Dual Inline Memory Module contains memory chips like a SIMM but actually provides a greater density of memory chips and therefore more RAM. DIMMs do not have to be installed in pairs, and there are typically three DIMM slots on a motherboard. This means that a computer with 256MB of memory would only require the installation of one 256MB DIMM.
RAM speed has been historically measured in nanoseconds (ns). The lower the nanosecond rating for the RAM, the faster the RAM. For example, 10ns RAM would be faster than 30ns RAM. The speed of newer RAM memory is now measured in MHz (as is the motherboard bus speed and processor speed).
As mentioned earlier, a number of different RAM types are available, and the type used is dictated by the motherboard used on the computer. Although memory has changed dramatically since the advent of the PC, the RAM types listed here are all types you might find on a motherboard designed for a Pentium processor (clone processor motherboard):
While the type of memory you use can enhance PC performance, the true bottom line is that the more RAM you have on a system the better the system's performance. Adding RAM to any computer will increase system throughput. The addition of RAM, in many cases, will even provide more of a performance jump than switching to a faster processor.
The first hard drive available for the original IBM PC boasted a capacity of 10MB (10 million bytes). Now it is common for hard drives or fixed disks to have capacities in excess of 40GB (that's 40 billion bytes). In fact, a 40GB hard drive is now considered quite small in comparison to the large capacity drives that are available.
Hard drives come in two flavors: IDE drives and SCSI drives. An Integrated Drive Electronics (IDE) drive is a hard drive (or other device such as a CD-ROM) where the controller for the drive is built in to the drive itself. An IDE drive is connected to the motherboard using a ribbon cable. Each motherboard IDE connection supports up to two IDE drives. Motherboards typically have two IDE connections, meaning a maximum of four IDE drives (this includes hard drives and CD-ROM drives) could be installed on the computer.
Small Computer System Interface (SCSI) hard drives are attached to a SCSI controller card (placed in one of the motherboard's expansion slots or built right onto the motherboard, in the case of servers). SCSI controllers allow for the attachment of more drives (up to seven); therefore, SCSI drives are pretty much the standard for server computers.
In terms of server hardware, SCSI hard drives are preferred over IDE drives because SCSI drives boast a 12% performance boost over their IDE counterparts. Also, only two IDE drives can be connected to the motherboard via the same ribbon cable (limiting a computer to a maximum of four IDE drives connected to the motherboard). On the other hand, one SCSI controller will support up to seven drives, which makes it easier to deploy multiple-drive configurations, such as a RAID array (RAID is discussed in the section titled "Working with RAID," in Chapter 18, "Protecting Network Data").
Network Server Considerations
Network servers require large storage capacity, fast processors, and ample memory. Server tower cases also are larger than client computers and provide much more space for additional hard drives and other peripherals.
Server computers often have motherboards that provide space for more than one processor. Most network operating systems are built to take advantage of multiple processors. In fact, some network operating systems support up to 32 processors.
Servers also typically contain many more hard drives than you would find on a client machine and usually contain SCSI hard drives rather than IDE drives (which you would typically find on a client computer). This is not only to provide adequate storage space but also to build in some redundancy for storing files. We will talk about how drive redundancy can be used to help keep important data safe in Chapter 18. The SCSI controllers are also typically part of the server's motherboard rather than an add-on card.
The hardware configuration for a server will, to a certain degree, be dictated by the network operating system running on that server. Each network operating system provides a baseline configuration for a server that will run that NOS. We look at network operating systems in Chapters 8, 9, and 10; where we discuss Novell NetWare, Microsoft Windows Server 2003, and Red Hat Linux, respectively. You will see that each of these network operating systems have recommended baseline hardware server configurations (detailed in each of the chapters).
Network operating systems are also generally less forgiving when you attempt to run them on computers with odd configurations or atypical hardware. NOS software companies often provide a hardware compatibility list that allows you to view what types of server hardware have been tested with the particular operating system.
Before you actually finalize your server configurations, you need to do some research on the NOS you will be running. Novell, Microsoft, Red Hat, Sun Microsystems, and other NOS providers typically provide white papers and other material that allow you to look at case studies and performance data related to a particular NOS and various hardware configurations.
Network Client Considerations
Network clients don't typically need the processing power and storage capacity required by a server computer. Network clients do need, however, to be able to properly run the client operating system they have been configured with. Be sure that a client machine has at least the minimum hardware configuration to run the client operating system.
As with network operating systems, client operating systems will also often have hardware compatibility lists that provide you with a listing of the type of computer hardware that has been tested with the OS. As with servers, the more robust the hardware configuration of the computer, the faster (and better) the OS will run on the system.
A Final Word on Computer Hardware
To buy or to build? That is the question. Although the very low price of computer components may seem like a fairly seductive reason to build computers for a network, prebuilt PCs are configured with components that the computer manufacturer knows (or should know) work well together. Computer manufacturers also provide warranties and service plans. And in most cases they also provide excellent support. So, why build PCs? Adding RAM or hard drives to a PC is one thing, but building a bunch of computers from components may be nothing more than a major headache .
With computer hardware prices continuing to drop, you can purchase PCs from any number of computer manufacturers that will provide you with excellent desktop and server systems. Do your research before buying and make sure that you configure your servers and desktop computers to take care of the job for which they were intended.