Potential Bandwidth-Related Solutions; In Summary - Red Hat ENTERPRISE LINUX 3 - INTRODUCTION TO SYSTEM ADMINISTRATION Administration Manual

Chapter 3. Bandwidth and Processing Power

3.1.4. Potential Bandwidth-Related Solutions

Fortunately, bandwidth-related problems can be addressed. In fact, there are several approaches you
can take:
Spread the load
•
Reduce the load
•
Increase the capacity
•
The following sections explore each approach in more detail.
3.1.4.1. Spread the Load
The first approach is to more evenly distribute the bus activity. In other words, if one bus is overloaded
and another is idle, perhaps the situation would be improved by moving some of the load to the idle
bus.
As a system administrator, this is the first approach you should consider, as often there are additional
buses already present in your system. For example, most PCs include at least two ATA channels
(which is just another name for a bus). If you have two ATA disk drives and two ATA channels, why
should both drives be on the same channel?
Even if your system configuration does not include additional buses, spreading the load might still be
a reasonable approach. The hardware expenditures to do so would be less expensive than replacing an
existing bus with higher-capacity hardware.
3.1.4.2. Reduce the Load
At first glance, reducing the load and spreading the load appear to be different sides of the same coin.
After all, when one spreads the load, it acts to reduce the load (at least on the overloaded bus), correct?
While this viewpoint is correct, it is not the same as reducing the load globally. The key here is to
determine if there is some aspect of the system load that is causing this particular bus to be overloaded.
For example, is a network heavily loaded due to activities that are unnecessary? Perhaps a small
temporary file is the recipient of heavy read/write I/O. If that temporary file resides on a networked
file server, a great deal of network traffic could be eliminated by working with the file locally.
3.1.4.3. Increase the Capacity
The obvious solution to insufficient bandwidth is to increase it somehow. However, this is usually an
expensive proposition. Consider, for example, a SCSI controller and its overloaded bus. To increase its
bandwidth, the SCSI controller (and likely all devices attached to it) would need to be replaced with
faster hardware. If the SCSI controller is a separate card, this would be a relatively straightforward
process, but if the SCSI controller is part of the system's motherboard, it becomes much more difficult
to justify the economics of such a change.

3.1.5. In Summary. . .

All system administrators should be aware of bandwidth, and how system configuration and usage
impacts available bandwidth. Unfortunately, it is not always apparent what is a bandwidth-related
problem and what is not. Sometimes, the problem is not the bus itself, but one of the components
attached to the bus.
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