問75
頻出度★★☆
デュアルシステムの特徴を説明したものはどれか。
平成28年度 春期 ITパスポート試験 問75
テクノロジ系システム構成要素 › システムの構成
This question's explanation and your answers so far.
解説
問 75
- ア
正解 The correct answer is ア. A dual system is a reliability-focused configuration in which two systems performing exactly the same processing are prepared and run in parallel, and the correctness of the processing is verified by cross-checking the results of both. Even if one of the systems fails, the faulty system can be disconnected and processing continued with only the remaining system, so operation can be maintained without any downtime. ア describes exactly this characteristic of duplicating the processing and matching the results, neither adding nor omitting anything, so it is correct.
Incorrectイ
This describes using two identical devices to double the processing capacity compared to a simplex system, which is about a configuration aimed at boosting processing capacity. The purpose of a dual system is to ensure reliability by comparing results; because it runs the same processing in duplicate, its processing capacity is not doubled. It is wrong as a description of the characteristic.
Incorrectウ
This describes a method that prepares an active system performing online processing and a standby system that waits while performing tasks such as batch processing, and switches to the standby system when the active system fails. This is a characteristic of a duplex system (a standby-switchover method), which differs from a dual system that constantly processes in duplicate and compares the results.
Incorrectエ
This describes a configuration that connects multiple devices in series and distributes the load by function, where the service stops if even one of them fails. This is a characteristic of a series (tandem) configuration, which is vulnerable to a single failure and has no redundancy. It is the exact opposite of a dual system that can keep processing even when a failure occurs, so it is wrong.
ここがポイント
- Dual system = a reliability-focused configuration that runs two systems performing the same processing in parallel and verifies correctness by cross-checking the results. When one system fails, it is disconnected and processing continues.
- Distinguishing it from similar configurations: do not confuse it with a duplex system that switches over to a standby system, or a tandem configuration that connects devices in series and distributes functions (weak against a single failure).
用語