Performance Issues (Hardware)

Improving Network Performance

There are many things you can do to make your network perform better with a multi-user database application such as CAPITAL. Database applications have requirements that are different from word processors and spreadsheets. Much greater demands are placed on your network "throughout" or "bandwidth" and the speed of your hard disk subsystem. The most important issues to consider are:
 

    Your network server.

    Your network server specification and configuration.

    The network topology. This covers network cards, cables, hubs (or switches) and techniques such as subnetting.

    Other traps and problems to watch for.

File Server Hardware For Your Network

The system requirements for a network file server will be at least the same as those for any PC connected to your network, but this should be considered the absolute minimum. A file server should normally be a faster, higher-capacity system, as it must handle file requests from multiple computers across your network. Network file servers may also be responsible for handling your company e-mail and Internet access, web site, printing, etc. These tasks also consume resources and can adversely effect performance. For example, if your server is also handling web site access and access to your web site is heavy, your local network performance is likely to be poor because the server will be overloaded. In these cases you will need to set-up additional servers to manage some of these tasks in order to restore your local area network's speed.

A network file server should not be used like a regular PC in your company. No one should run business applications such as Microsoft Office or even CAPITAL on it for routine data entry tasks. (Although you may wish to run certain CAPITAL applications on it such as Visual Builder handling printing requests, so long as this does not adversely effect overall performance.) Although the CAPITAL application and your business databases are stored on the server's hard drives for everyone to share, most applications should not be run directly from the server.

The most important aspects of a good file server is the drive system(s), memory and network cards or adapters. These issues can affect how quickly your networked PC's can gain access to the files on the server.

Memory

Add as much memory (RAM) as possible to maximize disk caching performance. Windows NT assigns approximately half of its available memory to its disk cache. If your company database is 250MB, you would require 500MB to cache the entire database. This will permit maximum caching performance. Adding more memory after this will then not significantly add to performance. However, keep in mind that you may be running other applications besides CAPITAL so more disk cache may help to improve performance. As well, it is seldom the case that all users will be accessing all areas of your company database in the one session. So often you can still get excellent performance by having less memory than the total size of the database. The golden rule is to install as much memory as you can afford up to the total size of your database.

Hard Disk Drives

Most hard drives available today offer good performance and the choice of drive will have less effect on your server's performance than the amount of memory. You should consider using SCSI drives (SCSI-II or SCSI-III or later versions are the best), instead of IDE or ATA drives. SCSI drives cost more and require a separate hard disk drive controller. The main advantage of SCSI drives is that the SCSI design is optimized for handling multiple disk requests simultaneously, which is exactly the kind of task a server will be occupied performing. Most server rated computers include SCSI drive technology already.

Network Adapter Cards

All data transferred by the computers on your network has to travel through the server's network adapter. Special network cards are available specifically for servers to improve performance. They run faster and/or offer more on-board memory (in order to improve buffering) and/or offer additional features such as the ability to better handle requests from multiple computers simultaneously. You could, for example, install a "fast Ethernet" adapter such as 100baseT or something of equivalent or better performance. Another option is to install multiple network adapter cards and split your network into subnets. (This is discussed further below.)

Network File Server Configuration

Server hardware has the most affect on server performance. However, a poorly configured server will run slowly regardless of the hardware installed in it. The following recommendations are specific to Microsoft Windows NT, but there are equivalent concepts in Novell NetWare:
 

    Avoid overloading your server. Upgrade any weak components if necessary.
 

    Do not run any unnecessary processes on your server, espcially if those tasks can be delegated to another machine. The main purpose of your file server should be to "serve files".
 

    The NT swap file should be at least 150MB, and preferably 2-2.5 times the amount of server memory. For example, if your file server has 256MB, you swap file should be in the 512-640MB range.
 

    Do not run a screen saver on your server console, especially the OpenGL 3D screen saver that comes with Windows NT. Screen savers running on your server consume CPU cycles, which hurts performance. If your server sits in a room with its monitor turned off, you may not even realize the screen saver is running. Since you can usually run your server with the monitor turned off anyway, there is no need to activate a screen saver or any unimportant foreground task.

Network Speed and Topology

All computers on your network share access to your network cable, and this is often the cause of poor network performance. Even a high performance server will be crippled if the network connections are inadequate.

The most common problem that affects network performance is not the speed of the server or your PC's, but the speed of the network itself. This includes the the network adapter cards, cabling and hubs or switches. The amount of data throughput (how much can be moved how quickly) is referred to as the network bandwidth. The more bandwidth you have, and the more efficiently you use it, the faster your network will run.

For ethernet networks in particular, there are several things you should do:
 

    Use switches, which route traffic intelligently, rather than "dumb" hubs, which simply broadcast all network traffic to all workstations. (Note: There is also a device called a "switched ethernet hub", which is a type of hub that suffers from lack of routing capabilities. A real ethernet switch will perform much better than a switched ethernet hub.)
 

    If you are running 10baseT (10 megabit speed or even older 8 megabit coax), upgrade to 100baseT (100 megabit). 100baseT is now very affordable and the network adapters, hubs and switches cost only marginally more than the older and slower technology.
 

    Divide your network into subnets, each with its own switch and its own connection to the server (i.e. install multiple network adapter cards in the server). This reduces traffic on each section of your network and therefore makes more server bandwidth accessible.
 

The concept of subnets and switches is similar. When you have a "dumb" hub-based system, every data packet on the network gets broadcast to all PC's. With an application such as CAPITAL Series 7, where many users are simultaneously doing searches, generating reports, entering transactions, etc., a great deal of traffic can be generated. When one user does a search, the traffic he creates is seen not only on his PC, but all other networked PCs as well. If you have a lot of busy users, you have a lot of traffic. The result is that your moving data gets trapped in a traffic jam.

With subnets your groups of heavy users are divided into smaller subgroups. Each subgroup only deals with the traffic for its members, thus reducing congestion. With switches this can be improved further: each PC has its own "private road" going directly to the server, because the switch routes the traffic intelligently, instead of broadcasting it to every PC on the network.

Other Traps and Problems

These additional techniques apply to servers and networked PC's:
 

    If you use virus scanner software such as McAfee ViruScan or Norton AntiVirus on your server or local PC's, check to see if it is set to scan all files, regardless of file type. If it is, this will slow down your accounting system considerably, because every time CAPITAL opens and reads a database, the virus scanner rescans the file. Change your virus scanner settings to exclude DBF and CMX files or preferably all files in your CAPITAL company directories. Viruses cannot be active or propagate from inside CAPITAL database files and so do not pose a threat to your network. A quick test can be done by temporarily shutting down the antivirus software to see if network transmission speeds improve.
 

    Make sure your server and your local PC's do not have drive letter mappings or printer mappings to servers or printers that do not exist, are turned off, or are not always accessible. This slows down Windows and all its file operations.
 

    Use drive letter mappings to access files on your server, not UNC (Universal Naming Convention) paths, which are much slower. For example, your database path should be something like F:\CAPITAL, not \\myserver\myprograms\Capital
 

    Network speed problems can also be caused by hardware issues such as loose cables, faulty wiring, bad network adapter cards, network cards that are incompatible with the operating system, etc.
 

Please note that this discussion is not meant to be comprehensive. The issues raised in this document should be discussed in depth with your networking consultant. As technology is changing all the time, your network consultant will be in the best position to recommend the best technology for your organisation to use, as it becomes available.

31/01/02