Reliability of a Storage Cluster Case Study for BlockSim 7

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BlockSim 7 Case Studies

Case Study RC1 - Reliability of a Storage Cluster

Software Used:
BlockSim 7

Reference
This case study is based on the example shown in Figure 8 of the article "Determining the Availability and Reliability of Storage Configurations" by Santosh Shetty, August 2002, as posted on Dell's Web site.

Analysis
Consider a "high-availability" cluster with a reliability block diagram (RBD) as shown in the next figure.

[Click to Enlarge]

Furthermore (and from the referenced Web article), assume the following life distributions and parameters. (Note that this example, unlike the original article, assumes no repair of failed components.)

Server: Exponential (Mean = 45753 hr)
Switch: Exponential (Mean = 255,358 hr)
HBA: Exponential (Mean = 252,550 hr)
Controller: Exponential (Mean = 68,961 hr)

Step 1: Determine the "reliability equation" and cdf of the system...
Figure 1 illustrates BlockSim being used to determine the system reliability function.

Figure 1 [Enlarge]

You can also view the system reliability equation and cdf in HTML format.

Step 2: Looking at some system level plots...
Component Reliability Importance Plots
The next two charts are component reliability importance plots at t = 8544 hr (1 year). Both plots (a tableau area plot and a bar chart) illustrate the same concept. That is, the higher the importance of the component, the higher its effect on system reliability.