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System Architecture and Reliability

The servers of a semiconductor fab's manufacturing execution system (MES) are made a duplex system consisting of a primary (active) system and a standby system. Which is a characteristic when the standby system is a hot standby?

  1. AThe standby system is kept running and the primary's data is always reflected to it, so processing can switch over in a short time when the primary fails
  2. BThe standby system is kept powered off and is started and has its data restored after the primary fails, so switching over takes time, but power and cost while waiting are kept low
  3. CThe primary and standby systems perform the same processing at the same time and operate while comparing the results
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Answer: A. The standby system is kept running and the primary's data is always reflected to it, so processing can switch over in a short time when the primary fails

A hot standby keeps the standby system running and always reflects the primary's data to it, so it can take over processing in a short time when the primary fails. If the MES stops, the fab can no longer direct how lots move, specify recipes to equipment or record manufacturing history, so a configuration that can switch over in a short time is generally chosen. Keeping the standby stopped and starting it after a failure is a cold standby, and the intermediate case (running, but needing preparation before taking over processing) is called a warm standby. Performing and comparing the same processing on two systems at the same time is a dual system.

  • A. Correct. The standby is kept running with its data synchronized, so it can switch over immediately.
  • B. This describes a cold standby.
  • C. This describes a dual system.
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