The Network Server

It is desirable to have a network built around a centralized server as opposed to a peer to peer network in which data and other resources such as printers are on individual desktop computers. A centralized server offers better manageability and enhanced security among other benefits.

A server is not just another computer. Servers are designed and manufactured with one goal in mind: reliability. Some special features found in a server are:

• ECC Memory - Error Checking & Correcting Memory. Redundancy built into the memory subsystem allows errors to be detected, logged, and in most instances, corrected.
• Automatic Restart - the Network Operating System may get into a mode where it is stuck or hung and no more useful work is being done. The server detects this and automatically restarts.
• Pre-failure warranty - Correctable errors and other inconsistencies in the memory and disk subsystems are logged. The manufacturer will exchange the parts as a warranty replacement based on these logs before the parts actually fail.
• 3-year warranty on parts and 3-year, second business day, on-site warranty on labor on all Compaq servers.

Data Storage Configuration

One of the things that a server can do well is to act as a safe central storage location for company-wide data. The network is configured to give every user access to network drives. These drives appear to be local to their desktop computers but actually reside on the server. The network is set up to store all work documents on the server.

When a drive fails and there is no redundancy, data must be restored from the latest backup tape. All new data entered from the time that the backup was made till the time of the failure will be missing. Some server system settings are also invariably lost. Even one such failure will end up costing much more than the initial cost of building redundancy into the server.

These server options almost eliminate the possibility of losing data:

• RAID Level 1 - software implementation.Uses software built into Windows NT to mirror the system disk to a standby disk. When one disk fails the server keeps running. When convenient, the server is shut down and the failed disk is replaced. No data loss occurs. There is some server down time. Disk utilization is only 50% (i.e. a system with two 4.3GB drives stores only 4.3GB). Low cost option for entry level servers.
• RAID Level 1 - hardware implementation.Uses a special hardware RAID controller to mirror the system disk to a standby disk. This option is similar to the previous one but is more efficient and offers faster and easier recovery in case of a failure.
• RAID Level 5 - hardware implementation.A group of 3 or more drives are combined to look like a large storage area. Any one drive can fail and the system will keep running. Recovery is like RAID Level 1 above. There is minimal server down time. Special hardware controls the drives. Storage is less wasteful (i.e. a system with three 4.3GB drives stores 8.6GB or 67%, with four drives this goes up to 75% etc.).
• Hot Swap Drives.Used when no server down time can be tolerated. When a drive fails it can be replaced without shutting down the server.

Power Supply Redundancy

This feature is found on higher end servers. One supply can fail and another takes over without affecting the server. The failed supply can be replaced without shutting down the server.

Backup Options

• Internal or external backup tape drive. The drive should be large enough to store the backup data on one tape and fast enough to complete the backup at night.
• Tape autochanger. This option is needed if the backup cannot fit on one tape or if the backup tape must be changed every night automatically.

Sizing Information

How big and powerful does a server need to be? Answering the following simple questions will help to determine that:

Total number of workstations presently used : ?????

Average space for user files per workstation (MB) : ?????

Space used by special purpose database or application : ?????

Total disk space needed on the server : ?????
(This answer depends partially on the questions above and will be configured by EMETEK).

Total RAM needed on the server : ?????
(This depends on several different variables and an optimal value will be configured by EMETEK).

How many simultaneous Remote Access connections? : ?????

Extra Serial Communication ports needed : ?????