Disk Monitoring Concepts

You need to observe many factors in determining the performance of a disk system. These include the level of utilization, the rate of throughput, the amount of disk space available, and whether a queue is developing for their disk systems. It is also important to monitor other types of activity that arise from disk operations, such as interrupts generated by the disk system and paging activity, because of their influence on other resources, such as processor or memory.

Figure 8.1 illustrates the importance of monitoring disk systems in relation to the overall performance of your system.

Figure 8.1 Role of Disk Monitoring in System Monitoring

Many of these factors are interrelated. For example, if utilization is high, transfer rates ( throughput ) might peak, and a queue might begin to form. These conditions might result in increased response time and cause performance to slow. Although disk space doesn't directly affect the disk's transfer rate, when extremely low, disk space can also have an influence on response time because applications that read and write data can't do so as efficiently. Detect these performance issues through monitoring before they cause problems.

This chapter covers the following stages of a disk-monitoring strategy:

• Configuring the disk and file system for best performance

• Working with disk counters to monitor your disk space and disk efficiency

• Establishing a baseline for disk performance

• Investigating performance problems