Abstract: A method of calculating single and dual parity for a networked array of storage elements is presented. The method includes deriving a first set of n relationships where each of the first set of n relationships consists of an XOR statement equaling zero. Each of the first set of n relationships contains n data symbols from n storage elements and one parity symbol from a first set of parity symbols. The method also includes deriving a second set of n+1 relationships where each of the second set of n+1 relationships consists of an XOR statement equaling zero, containing at least n?1 data symbols from at least n?1 storage elements and one parity symbol from a second set of parity symbols. Using both the first and second sets of derived relationships, scripts are generated to resolve unresolved symbols resulting from possible single- and dual-storage element failure combinations.

Abstract: A disk array utilizes a surviving relationship algorithm for generating parity terms. During a drive failure, a script corresponding to the failure mode (e.g., single storage element failure or dual storage element failure) is executed. The script reconstructs data by deriving a surviving relationship matrix from a seed matrix, sending the resulting surviving relationship matrix to parity/data generators in the storage controller, and generating P parity and Q parity symbols based on the inputs from the relationship matrix. The surviving relationship matrix is independent of symbol position (i.e., row, column, or diagonal) and further ensures that all data is reconstructable after single or dual storage element failures.

Abstract: A improved connection shaping technique is disclosed, whereby at least one high-priority “preemptive” service flow is initiated at a customer entity in order to limit or restrict the effective usable bandwidth on a particular line or connection. According to at least one embodiment, a preempt data parcel corresponds to a data parcel which includes non-meaningful data. When the preempt cells are received at the ingress port of the communication line, the preempt cells may be identified as non-meaningful data parcels, and may be discarded in accordance with conventional protocols.

Abstract: A technique is described for providing service to multiple ports sharing common scheduling resources. According to one implementation, the scheduling technique of the present invention may be used to dynamically balance the frequency of needs of different client flows to the resource availability of the scheduling process for client flows which have relative time sensitive needs of service. Moreover, according to a specific implementations, the scheduling technique of the present invention may be used to provide efficient allocation of switching and/or scheduling resources across multiple ports even in the presence of dynamic port bandwidth changes.

Abstract: A technique is disclosed for scheduling data parcels from at least one client process to be output for transmission over a first communication line having an associated first bit rate. The at least one client process may include a plurality of client processes, each having a respective, associated bit rate. A plurality of data parcels associated with the client processes are identified by a scheduler. The scheduler performs scheduling operations and selects specific client data parcels to be included in an output stream provided to physical layer logic for transmission over the first communication line. An appropriate ratio of “filler” data parcels to be inserted into the output stream is determined. The “filler” data parcels correspond to disposable data parcels which do not include meaningful data. The output stream generated by the scheduler may include a uniform pattern of client data parcels (e.g.

Abstract: An architecture and techniques of the present invention combine multiple queues into a single multientity queue that functions in conjunction with a free queue embodied within the multientity queue. This multientity queue enables a device to significantly decrease overhead of memory clock cycles as data parcels are passed from process to process. The architecture implements a single queue with new pointers in addition to the “old” and “new” pointers associated with conventional queues. These new pointers represent processes or entities and can be referred to as first entity pointer, second entity pointer, third entity pointer and so on.

Abstract: Method and apparatus for buffering data packets in a data communication controller environment. In general, the communication controller is interfaceable with a host processor and includes a control unit for accessing a communication medium. Each data packet to be transmitted or received is assigned a unique packet number. Packet number assignment is carried out by a memory management unit which dynamically allocates to each assigned packet number, one or more pages in data packet buffer memory for the storage of the corresponding data packet. If requested storage space is unavailable at the time of request, the memory management unit will allocate a page or pages to an available packet number as the pages become free. Upon issuing the assigned packet number, the physical addresses of the allocated pages of buffer memory storage space are generated in a manner transparent to both the host processor and the control unit.

Abstract: Method and apparatus are disclosed for buffering data packets in a data communication controller. The communication controller is interfaced with a host processor and includes a control unit for accessing a communication medium. Each data packet to be transmitted or received is assigned a packet number. Packet number assignment is carried out by a memory management unit within the communication controller which dynamically allocates to each assigned packet number one or more pages in a data packet buffer memory for the storage of the corresponding data packet. Upon issuing the assigned packet number, the physical addresses of the allocated pages of data packet buffer memory storage space are generated in a manner transparent to both the host processor and the control unit.

Abstract: A machine tool controller and part inspection monitor that controls part cutting by a machine tool (21) and provides a readout of cutter deviation beyond a preset tolerance is disclosed. Axis position sensors (23) continuously sense the position of the part (if the part is moved), the position of the cutter (if the cutter is moved) or the position of the part and the cutter (if both are moved) along various control axes. A data processor (31) uses the sensed axis position data to continuously determine the transfer function of the machine tool (21). The data processor (31) combines the transfer function information with data that defines the centerline of the cut to produce control signals suitable for controlling part and/or cutter movement. The location and amount of deviation from the defined centerline greater than the allowable tolerance are recorded and read out.