|
|||||
![]() |
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
![]() |
|
![]() |
A network in which the workstations connect only to servers (as opposed to each other, as in a peer-to-peer) is called a client/server network. In addition to its local operating system (usually DOS or one of the Windows operating systems), each workstation runs network software (client software) that enables the workstation to communicate with the servers. Windows 95 itself contains the client software necessary to connect to Novell NetWare 3.12 and 4.x, IBM OS/2 LAN Server, and Windows NT networks. In turn, the servers run network software (server software) that communicates with the workstations and serves up files and other services to those workstations. LAN-aware application software runs at each workstation, communicating with the server when it needs to read and write files. WorkstationsA LAN is made up of computers. You will usually find two kinds of computers on a LAN: the workstations, usually manned by people on their individual desktops, and the servers, usually located in a secured area, like a separate room or closet. The workstation is used only by the person sitting in front of it, whereas a server allows many people to share its resources.. Many existing network operate very well with older machines, however. Some sites even continue to use diskless workstationsthat is, computers that do not have a disk drive of their own. Such workstations rely completely on the LAN for their file access. A diskless workstation requires a NIC with an autoboot PROM. This type of ROM causes the workstation to boot from files store on a network server. The advantages to this type of workstation are lower cost for hardware and greater security, which is increased by not having any drives at the local workstation with which to copy files to or from the server. The primary disadvantage is that todays high-performance operating systems will n not run efficiently from a network drive. The sheer number of program files opened and closed, as well as the need for frequently swapping of memory to hard disk space, make the practice prohibitive. File ServersAll the workstations on a peer-to-peer LAN can function as file servers, in tt any drive on any peer workstation can be shared with (or served to) other users. On a client/server network, however, a file server is a computer that serves all the workstationsprimarily by storing and retrieving data from files shared on its disks. The server normally operates unattended, and almost always has one or more fast, expensive, large hard disks. Servers must be high-quality, heavy-duty machines because, in serving the whole network, they do many times the work of an ordinary workstation computer. In particular, the file servers hard disk(s) need to be durable and reliable, and geared to the task of serving multiple users simultaneously. For this reason, SCSI hard drives are usually preferred over IDE drives in todays servers . You will most often see a computer wholly dedicated to the task of being a server. Sometimes, on smaller LANs, the server doubles as a workstation, depending on the network operating system being used. Serving an entire network is a big job that does not leave much spare horsepower to handle workstation duties, however, and if a user locks up the workstation at also serves as the file server, your network also locks up. Under a heavy load, if there are 20 workstations and one server, each workstation can use only 1/20th of the servers resources. In practice, though, most workstations are idle most of the timeat least from a network disk-file-access point of view. As long as no other workstation is using the server, your workstation can use 100 percent of the servers resources. Evaluating File Server HardwareA typical file server consists of a personal computer that you dedicate to the task of sharing disk space, files, and possibly printers. On a larger network, you may use a personal computer especially built for file server work (a superserver), but the basic components are the same as those of a desktop PC. No matter what sort of computer you choose as a server, it communicates with the workstations through its network adapter cards the LAN cables. A file server does many times the work of an ordinary workstation. You may type on the servers keyboard only a couple of times a day, and you may glance at the its monitor only infrequently. The servers CPU and hard disk drives, however, take the brunt of responding to the file-service requests of all the workstations on the LAN. If you consider your LAN an important part of your investment in your business (and it is hard to imagine otherwise), you will want to get the highest quality computer you can afford for the file server. If youre going to be running on the Intel platform, the processor should be a Pentium, Pentium Pro, or Pentium II, and it should be one of the faster models. The hard disk drives should be large and fast, although in some cases the highest capacity drive available is not necessarily the best choice. When you consider that the server will be processing the file requests of many users simultaneously, it can be more efficient to have, for example, nine 1G SCSI hard drives rather than one 9G drive. That way, the requests can be spread across several different units, rather than queued up waiting for one device. Performance is important, of course, but the most crucial consideration in purchasing a server is that the CPU, the motherboard on which the CPU is mounted, and the hard disk drives should be rugged and reliable. Do not skimp on these components. Downtime (periods when the network is not operating) can be expensive because people cannot access their shared files to get their work done. Higher quality components will keep the LAN running without failure for longer periods of time. It is very important that you configure your LAN properly. Be sure that you have enough slots for all your present adapters and any future adapters that you can anticipate. It is also very important that you follow the RAM and hard drive sizing guidelines for your network operating system. In the same vein, you will want to set up a regular maintenance schedule for your file server. Over the course of a few weeks, the fans within the computer can move great volumes of air through the machine to keep it cool. The air may contain dust and dirt, which accumulates inside the computer. You should clean out the dust bunnies in the server every month or two. Many larger network sites house their servers in rooms or closets designed to maintain low dust and static levels as well as constant temperatures.
![]() |
![]() |
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
![]() |
![]() |