問86
頻出度★★★
デュアルシステムに関する記述として, 適切なものはどれか。
平成21年度 秋期 ITパスポート試験 問86
テクノロジ系システム構成要素 › システムの評価指標
This question's explanation and your answers so far.
解説
問 86
Incorrectア
A configuration in which one computer carries multiple microprocessors (CPUs) for parallel processing describes a “multiprocessor system”. It is a method for raising processing performance, and differs from a dual system, which runs two sets and cross-checks the results, in both purpose and structure.
- イ
正解 A dual system is a high-reliability configuration in which two identically configured computers run at the same time, perform the same processing, and operate while cross-checking each other's processing results. If the results agree, the processing is judged correct and continues; if they disagree, an abnormality is detected, the failed side is disconnected, and processing continues on the normal side alone. In other words, both “running things in duplicate” and “matching the results against each other” are its characteristics, so イ, which states this, is appropriate. It is used in work where errors are not tolerated, such as bank online systems.
Incorrectウ
A method that switches to a standby machine to continue processing when a failure occurs describes a “duplex system”. Normally the standby side is doing other work or is stopped, and the two sides do not perform the same processing and compare results. This choice targets the confusion between dual and duplex.
Incorrectエ
A configuration in which multiple computers are connected in series to share functions corresponds to a tandem system (function distribution). It divides roles and passes processing along, and is not the redundancy concept of performing the same processing twice and comparing the results.
ここがポイント
- Dual system = a high-reliability method in which two sets run the same processing in parallel and cross-check the results to detect errors.
- Duplex system = a method that prepares an active side and a standby side and switches to the standby side on failure. Grasp how it differs from dual (running in duplicate plus cross-checking).
用語