The design concept of making a system go into a safe state when a failure or abnormality occurs. Examples include railway signals that fall to red or stop when they fail, and normally closed valves that close when power or air pressure is lost.
Japanese name: フェールセーフ
Fail-safe appears in 3 practice questions across 1 topic, including System Architecture and Reliability.
In fail-safe design, which state is safe on failure is considered and decided for each system. For a hazardous gas supply valve, closing is the safe side; for an elevator, stopping with the brakes applied is. Some systems, however, become dangerous by stopping, and for them the concepts of fail-soft, which keeps operating even with reduced function, or fault tolerance, which keeps the function despite failures, are needed instead of stopping.
Semiconductor manufacturing equipment handles toxic and flammable gases, so fail-safe design is widely used. Gas supply valves are normally closed types that open with air pressure and close by spring force when air pressure or power is lost. In addition, when exhaust stops or a gas leak is detected, interlocks automatically stop the gas supply.
Fail-safe aims to put the system into a safe state on failure, and in many cases stops its function. Fail-soft aims to isolate the failed part and keep operating, even with reduced function or performance. Fool-proofing targets incorrect human operation rather than machine failure, making incorrect operation impossible or harmless.
Answer: C. In a system where four servers share the processing, when one server fails the remaining three continue processing, though with reduced capacity
Fail-soft is the idea that when part of a system fails, the failed part is isolated and the system as a whole keeps operating, even with reduced function or performance. Continuing processing on the remaining three servers with reduced capacity when one of four fails is an example. Stopping on the safe side when a failure occurs is fail-safe, and preventing incorrect operation is fool-proofing.
Answer: A. Fail-safe
The concept of designing a system so that it goes into a safe state when a failure or abnormality occurs is called fail-safe. A normally closed valve closes by spring force when the air pressure or power that opens it is lost, so an abnormality in power or air leads to the safe state in which the gas stops. Continuing to operate with reduced function despite a failure is fail-soft, and preventing incorrect human operation is fool-proofing.
Fail-safe is considered when stopping keeps things safe, and fail-soft when stopping would cause problems. Things that are safe once stopped, like gases in manufacturing equipment, are made fail-safe, while things whose stopping has a large impact, like business systems used by many people, are made fail-soft and kept running even with reduced performance. Both may be combined in one system.
Yes. For example, a design that denies access, rather than letting users through, when the authentication server cannot be reached is fail-safe from a security standpoint. Because this lowers availability, which way to fall is decided according to the purpose of the system.
Stopping on the safe side when a failure occurs is fail-safe, and preventing incorrect operation is fool-proofing.
Which is an example of a design based on the fail-soft conc…The concept of designing a system so that it goes into a safe state when a failure or abnormality occurs is called fail-safe.
In semiconductor manufacturing equipment, normally closed g…Going into a safe state on failure is the fail-safe concept.
Among the approaches to improving system reliability, which…As an Amazon Associate I earn from qualifying purchases.
Fail-soft Burn-in Bathtub curve Fault tolerance Differential backup Dual system Duplex system Fool-proof Hot standby Incremental backup