Importance

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Abstract

An automated concurrent data backup system and method. The architecture of the present invention includes a CPU coupled to a primary controller. The primary controller is coupled by separate logical buses to at least a set of paired mirrored or shadowed primary data storage devices. On one of the logical buses, a backup device controller is attached. Attached to the backup device controller is a backup device. In normal operation, the primary controller writes data to both of the primary data storage devices. When a backup is desired, the primary controller is programmed to detect a specified 'trigger' signal from the CPU. The primary controller stops writing data from the CPU to both of the primary data storage devices. The backup device controller becomes the 'bus master' over one of the logical buses, in known fashion, and starts a backup operation with respect to the data stored on the primary storage device designated for being backed up. In effect, control of the designated primary data storage device has been turned over to a new controller, the backup device controller, after the primary controller has 'switched off' its control of the connecting logical bus. The backup device controller transfers the data that it reads from the designated primary data storage device to the backup storage device. The primary controller then again becomes the 'bus master' of the previously disconnected logical bus. The primary controller then resynchronizes the primary data storage devices so that data that has been written on the continuously operational data storage device is copied onto the designated data storage device. In an alternative embodiment, the primary controller is coupled by separate logical buses to at least a set of triplet or quadruplet mirrored or shadowed primary data storage devices. Triplet devices permit backup operation while retaining the redundancy characteristic of mirrored storage devices. Quadruplet devices permit continuous backup operation of two alternating storage devices while retaining the redundancy characteristic of mirrored storage devices.

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First Claim