Chapter Outline

3-2 Probability Distributions and Probability Mass Functions

3-3 Cumulative Distribution Functions

3-4 Mean and Variance of a Discrete Random Variable

3-5 Discrete Uniform Distribution

3-7 Geometric and Negative Binomial Distributions

A redundant array of independent disks (RAID) uses multiple physical disk drives as one logical unit in a computer system. The array can increase performance and robustness to a disk failure. Data copies can be written simultaneously to multiple drives (known as *mirroring*) to provide immediate backup and the ability to recover from failures but with less storage capacity than would otherwise be available. Alternatively, to increase performance, the data can be distributed among multiple disks with only a fraction of the data on each one (known as *striping*). But a failure to even a single disk can lead to loss of data. An intermediate design is to distribute the source data along with additional data (known as *parity data*) across multiple disks. With the parity data, the source data can be recovered even with disk failures. In particular, a RAID 5 design uses striping ...

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