1 Computer and Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved

2 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved Introduction A bottleneck (the slowest component in your computer network) causes work to get jammed up. The first step in improving network performance is to identify the bottleneck. The Hardware Inside your Servers Your servers should be powerful computers capable of handling all the work your network will throw at them. Don't cut corners by using a bottom-of-the-line computer that you bought at a discount computer store.

3 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved The following are the four most important components of your server hardware: Processor: Your server should have a powerful processor. As a general rule, any processor that is available in an $800 computer from a low-cost general appliance store is not a processor that you want to see in your file server. In other words, avoid processors that are designed for consumer-grade home computers. Memory: You can't have too much memory. Memory is cheap, so don't skimp. Don't even think about running a server with less than 2GB of RAM.

4 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved Disk: Don't mess around with IDE hard drives. To be respectable, you should have nothing but SATA drives. Network card: Cheap $14.95 network cards are fine for home networks, but don't use one in a file server that supports 50 users and expect to be happy with the server's performance. Remember that the server computer uses the network a lot more than any of the clients. So equip your servers with good network cards.

5 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved The Server's Configuration Options All network operating systems have options that you can configure. Some of these options can make the difference between a pokey network and a zippy network. Unfortunately, no hard-and-fast rules exist for setting these options. Otherwise, you wouldn't have options. The following are some of the more important tuning options available for most servers:

6 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved  Virtual memory options: Virtual memory refers to disk paging files that the server uses when it doesn't have enough real memory to do its work. Few servers ever have enough real memory, so virtual memory is always an important server feature. You can specify the size and location of the virtual memory paging files. For best performance, you should provide at least 1.5 times the amount of real memory.  For example, if you have 1GB of real memory, allocate at least 1.5GB of virtual memory. If necessary, you can increase this size later.

7 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved Disk striping: Use the disk defragmenter to optimize the data storage on your server's disks. If the server has more than one hard drive, you can increase performance by creating striped volumes, which allow disk I/O operations to run concurrently on each of the drives in the stripe set. Network protocols: Make sure that your network protocols are configured correctly and remove any protocols that aren't necessary.

8 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved Free disk space on the server: Servers like to have plenty of breathing room on their disks. If the amount of free disk space on your server drops suddenly low, the server chokes up and slows to a crawl. Make sure that your server has plenty of space — a few gigabytes of unused disk space provides a healthy buffer. Servers that do too much One common source of network performance problems is servers that are overloaded with too many duties. Just because modern network operating systems come equipped with dozens of different types of services doesn't mean that you should enable and use them all on a single server.

9 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved If a single server is bogged down because of too much work, add a second server to relieve the first server of some of its chores. Remember the old saying: "Many hands make light work.“ What Services does Microsoft Server 2003 have? There are many services available in Server It is important to remember when invoking a service on a Server, there should be no other service currently activated. The following screen shows what services are available.

10 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved

11 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved For example, if your network needs more disk space, consider adding a second file server rather than adding another drive to the server that already has four drives that are nearly full. Or, better yet, purchase a file server appliance that is dedicated just to the task of serving files. As a side benefit, your network will be easier to administer and more reliable if you place separate functions on separate servers. For example, if you have a single server that doubles as a file server and a mail server, you'll lose both services if you have to take the server down to perform an upgrade or repair a failed component. However, if you have separate file and mail server computers, only one of the services will be interrupted if you have to take down one of the servers.

12 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved The network infrastructure The infrastructure consists of the cables and any switches, hubs, routers, and other components that sit between your clients and your servers. The following network infrastructure items can slow down your network: Hubs: Because switches are so inexpensive now, you can affordably solve a lot of performance problems by replacing old, outdated hubs with switches. Using switches instead of hubs reduces the overall load on your network.

13 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved Segment sizes: Keep the number of computers and other devices on each network segment to a reasonable number. About 20 devices is usually the right number. (Note that if you replace your hubs with switches, you instantly cut the size of each segment because each port on a switch constitutes a separate segment.) The network's speed: If you have an older network, you'll probably discover that many — if not all — of your users are still working at 10Mbps. Upgrading to 100Mbps will speed up the network dramatically.

14 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved The backbone speed: If your network uses a backbone to connect segments, consider upgrading the backbone to 1Gbps. The hardest part about improving the performance of a network is determining what the bottlenecks are. With sophisticated test equipment and years of experience, network gurus can make pretty good educated guesses. Without the equipment and experience, you can still make pretty good uneducated guesses.

15 Network Bottlenecks Author: Rodger Burgess 27th October 2008 © Copyright reserved Malfunctioning components Sometimes a malfunctioning network card or other component slows down the network. For example, a switch may malfunction intermittently, occasionally letting packets through but dropping enough of them to slow down the network. After you've identified the faulty component, replacing it will restore the network to its original speed.

16 Author: Rodger Burgess 27th October 2008 © Copyright reserved The End