Abstract: An optical tape drive that performs direct read after write (DRAW) operations with a plurality of optical heads, each capable of reading data from and writing data to an optical tape. The optical tape drive includes control apparatus that positions each of the optical heads at any position along the width of the optical tape, that controls each of the optical heads to either read or write data, and that receives and moves the optical tape in either one of two directions. The control apparatus performs bidirectional DRAW operations by reversing the direction of the tape and swapping the read/write functions of corresponding head units aligned with a same track. The optical tape drive may include as few as two optical heads, each operable independent of the other, so that the drive may read or write up to two tracks at a time. DRAW operations are performed on multiple tracks by increasing the number of optical head units.

Abstract: A method for configuring devices in a computer system using pattern matching is disclosed. The method constructs the initial configuration pattern by retrieving and storing a working device configuration in the configuration pattern. For each resource item of a supported resource type of a device, the method generates a resource combination matching a configuration pattern, which is updated after each testing iteration, to check in a deterministic order for a configuration conflict until a non-conflicting resource is found. If a conflicting resource is found, the method has the option of moving the conflicting resource to a non-conflicting resource. The process recursively repeats itself for each supported resource type of a device to produce a device configuration matching the configuration pattern. Each next potential device configuration is deterministically generated using a configuration index and the configuration pattern.