100 Mbps. All it takes is one old 10Mbps component to slow down a whole segment of your network.
⻬ The backbone speed: If your network uses a backbone to connect seg-
ments, consider upgrading the backbone to 1 Gbps. The hardest part of 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 if uneducated guesses. In the remaining section of this chapter, I give you some pointers on
what to do after you’ve zeroed in on the bottlenecks — that is, tune the net- work to improve performance.
Tuning Your Network the Compulsive Way
You have two ways to tune your network. The first is to think about it a bit, take a guess at what may improve performance, try it, and see whether the
network seems to run faster. This approach is the way most people go about tuning the network.
Then you have the compulsive way, which is suitable for people who organize their sock drawers by color and their food cupboards alphabetically by food
groups. The compulsive approach to tuning a network goes something like this:
1. Establish a method for objectively testing the performance of some aspect of the network.
This method is called a benchmark, and the result of your benchmark is called a baseline. For information about how to test performance, see
the section “Monitoring Network Performance” later in this chapter.
2. Change one variable of your network configuration and rerun the test.
For example, suppose you think that increasing the size of the disk cache can improve performance. Change the cache size, restart the
server, and run the benchmark test. Note whether the performance improves, stays the same, or becomes worse.
3. Repeat Step 2 for each variable that you want to test.
Here are some salient points to keep in mind if you decide to tune your net- work the compulsive way:
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⻬ If possible, test each variable separately — in other words, reverse the changes you’ve made to other network variables before proceeding.
⻬ Write down the results of each test so that you have an accurate record of the impact that each change has made on your network’s performance.
⻬ Be sure to change only one aspect of the network each time you run the benchmark. If you make several changes, you won’t know which one
caused the change. One change may improve performance, but the other change may worsen performance so the changes cancel each other out —
kind of like offsetting penalties in a football game.
⻬ If possible, conduct the baseline test during normal working hours, when the network is undergoing its normal workload.
⻬ To establish your baseline performance, run your benchmark test two or three times to make sure that the results are repeatable.
Monitoring Network Performance
One way to monitor network performance is to use a stopwatch to see how long it actually takes to complete common network tasks, such as opening
documents or printing reports. If you choose to monitor your network with a stopwatch, you’ll want to get a clipboard, baseball cap, and gray sweatsuit
to complete the ensemble.
A more high-tech approach to monitoring network performance is to use a monitor program that automatically gathers network statistics for you. After
you’ve set up the monitor, it plugs away, silently spying on your network and recording what it sees in performance logs. You can then review the perfor-
mance logs to see how your network is doing.
For large networks, you can purchase sophisticated monitoring programs that run on their own dedicated servers. For small- and medium-size net-
works, you can probably get by with the built-in monitoring facilities that come with the network operating system. For example, Figure 14-1 shows the
Performance Monitor tool that comes with Windows Server 2003. Other oper- ating systems come with similar tools.
The Windows Performance Monitor lets you keep track of several different aspects of system performance at once. You track each performance aspect
by setting up a counter. You can choose from dozens of different counters. Table 14-1 describes some of the most commonly used counters. Note that
each counter refers to a server object such as a physical disk, memory, or processor.
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Table 14-1 Commonly Used Performance Counters
Object Counter
Description
Physical Free Space
The percentage of free space on the server’s Disk
physical disks. Should be at least 15 percent. Physical
Average Queue Indicates how many disk operations are
Disk Length
waiting while the disk is busy servicing other disk operations. Should be 2 or less.
Memory Pagessecond
The number of pages retrieved from the vir- tual memory page files per second. A typical
threshold is about 2,500 pages per second. Processor
Processor Indicates the percentage of the processor’s
Time time that it is busy doing work rather than
sitting idle. Should be 85 percent or less.
Here are a few more things to consider about performance monitoring: ⻬ The Performance Monitor enables you to view real-time data or to view
data that you’ve saved in a log file. Real-time data gives you an idea about what’s happening with the network at a particular moment, but
the more useful information comes from the logs.
Figure 14-1:
Monitoring network
perfor- mance in
Windows Server 2003.
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