デュプレックスシステムDuplex System

Learn in the textbookSystem Configurations for Availability and Reliability

DefinitionA duplex system (デュプレックスシステム) provides an active system (現用系, the primary) that handles live processing and a standby system (待機系, the secondary) kept ready in case it fails, and switches over to the standby system when a failure occurs.

ExplanationIn normal operation only the active system does live processing, and the standby system can take on other jobs while it waits. When the active system stops, processing moves to the standby system so work can continue, though service may pause briefly during the switchover.

AnalogyIt is like a bus company whose relief driver does office work most days and only takes the wheel when the regular driver suddenly calls in sick.

Memory hookIn English, a "duplex" is also a house split into two homes that share a wall. Picture the unit next door, always ready to move into.

Learn in the textbookReliability Design

DefinitionIn a duplex system (デュプレックスシステム), only the primary system handles the work in normal operation, while a second standby system waits in case of failure.

ExplanationThe primary system is also called the active system, and the standby system takes over processing when the primary fails. While waiting, the standby system may also be given other work. After the primary fails, processing stays stopped until the switch to the standby system is complete.

AnalogyThink of the starting player on the field and the substitute waiting on the bench for a turn.