Abstract: Data storage drives of an automated data storage library are allocated to received requests. A drive resource provider, upon receiving a request for a drive when all of the drives of the pool are allocated, holds any mount of a portable data storage cartridge relative to the request, releasing the hold when a drive is allocated. Spare drives are provided, outside of the pool. A spare drive may be allocated in response to the request, and a message is posted indicating use of the spare data storage drive. The posted message may comprise a notification that action may be taken to permanently transfer a spare data storage drive to the pool.

Abstract: A method and system for controlling access to a bus for transferring data in the form of multibyte data streams. Data transfer agents are coupled to and request access to the bus to transfer data thereon. The system for controlling access to the bus comprises a bus arbiter responsive to the access requests of the data transfer agents, granting access to the bus to one data transfer agent at a time. A data length counter accumulates, during the grant of access, signals indicating the length of the data transferred between the bus and the data transfer agent. The data length counter indicates completion of the transfer of a predetermined length of data, and bus arbiter logic responds to the data length counter indicating the transfer completion, causing the bus arbiter to terminate the grant of access to the data transfer agent. The control of access to the bus is thus based on the precise measurement of the length of the transferred data, rather than on timers.

Abstract: Verification of a primary or backup copy of vital information of a processing system employs a pseudo-fixed reference identifier, defined as an identifier unlikely to change over the life of the system, and controls which copy of vital information is correct. The primary copy of vital information is associated with a copy of the pseudo-fixed reference identifier and a backup copy of the vital information is associated with a copy of the pseudo-fixed reference identifier. A processor, when triggered, reads the pseudo-fixed reference identifier, compares it to the stored copies of the identifier of the primary and backup non-volatile storage. (1) If the read pseudo-fixed reference identifier matches the primary copy of the identifier, the processor indicates the vital information is valid. (2) If the read pseudo-fixed reference identifier matches the backup only, indicating that the backup copy of vital information is to be restore copied to become the primary copy.

Abstract: A servo system and method position a head laterally with respect to defined servo tracks, employing fine and coarse actuators. A servo control integrates the position error between the head and a desired position in accordance with a predetermined function, and operates the coarse actuator to translate the fine actuator and the head in accordance with the integrated position error. A position error signal loop is coupled to a servo sensor for determining position error for operating the fine actuator to translate the head in a manner to reduce the position error. The position error signal loop may have a compensator function with both integration and other functions. A coarse servo control comprises a connection coupled to the compensator function for providing an integration control representing the integration function of the position error signal loop; and a driver coupled to the connection, operating the coarse actuator to translate the fine actuator and the head in accordance with the integration signal.

Abstract: An adapter and a method for adapting a programmable digital maximum likelihood detector to a variable channel output and a calibration system for calibrating a programmable digital maximum likelihood detector from unknown data in a known code at a variable channel output, the maximum likelihood detector having a number of maximum likelihood states. A detector detects a digital sample of the recorded analog signals as corresponding to one of the maximum likelihood states. An accumulator partially accumulates the detected digital sample with prior detected digital samples corresponding to the one of the maximum likelihood states. Logic coupled to the accumulator employs the accumulated digital samples for the corresponding maximum likelihood state to determine at least one numerical metric coefficient matching the digital samples to the one of the maximum likelihood states, and updates or sets the numerical metric coefficient.

Abstract: A servo system and method position a head laterally with respect to magnetic tape longitudinal defined servo bands arranged in a longitudinally shifted pattern for identification, and separated by data tracks. A servo controller responds to a loss of lateral position, sensing an estimated longitudinal position of the magnetic tape. If the estimated longitudinal position is within a predetermined distance of an end of the tape, the servo controller operates a drive to continuously move the tape away from the sensed end. The servo controller senses a home lateral position sensor to determine whether a compound actuator is within a predetermined distance of the edge of the magnetic tape. If so, it operates the coarse actuator portion of the compound actuator to move laterally away from the edge of the magnetic tape; else, to move toward the edge.

Abstract: A system and method track and control the prefetching of blocks of a data stream in a PCI bus system, avoiding unnecessary prefetches. The data stream is grouped into major blocks which comprise a fixed plurality of contiguous blocks. A prefetch buffer stores the blocks of data prefetched from a PCI data source for transfer to a requester. First and second associated prefetch count storage locations store first and second counts initialized by prefetch initialization logic. The first count represents the number of blocks of data of a major block of the data, and the second count represents the total number of the blocks of the data stream to be prefetched, less the initialized number of blocks of the first count. As each block of data is prefetched, a prefetch counter decrements the first count by a number representing the block of data.

Abstract: A computer implemented method and a system for providing a redundant, updatable, self-booting firmware program. A sectored, non-volatile memory, having separately erasable sectors, stores at least two copies of operational code, each in at least one of the sectors separate from other of the copy sectors. Each operational code copy has information indicating the relative update level of the operational code copy, so that the copies may be separately updated and have different update levels. A boot program stored in at least one of the sectors of the non-volatile memory, separate from the operational code sectors, operates a processor to read the information from each of the copies to determine the most recent update level of the operational code copies, and executes the operational code copy having the most recent update level.

Abstract: A PCI read access management system and method to manage read access between two agents providing PCI read requests to conduct contiguous read operations to a central resource at a PCI bus. Dual transaction control logic units are each respectively coupled to a separate one of the agents. An arbitration request connection couples the dual transaction control logic units. A PCI read request by one of the agents (e.g., agent A), and recognized by one of the dual transaction control logic units (e.g., unit 1), is signaled to the arbitration request connection, which arbitrates between the transaction control logic units for reserving the PCI bus for the one agent (agent A), and the one transaction control logic unit (unit 1) provides read access to the PCI bus for the one agent (agent A) for the contiguous read operations. The one transaction control logic unit (unit 1) then maintains the reservation until completion of the contiguous read operations.

Abstract: A gripper for clutching cartridges for transport in a computer information storage library. The library includes storage locations for the data cartridges, a transporter with the gripper for moving the cartridges between the storage locations and a read/write cartridge drive. The gripper provides a positive grip on the end of the cartridge by providing a positive retention finger to hook into the centrally located lip provided on the bottom of the cartridge and at least one opposing finger to contact the top of the cartridge to balance the mechanical forces between the positive retention finger and the opposing finger.

Abstract: A shock mount structure facilitates shock absorption for a device. An outrigger, preferably two wing-like outriggers at diametrically opposite sides of the device, is mounted to the device at an attachment point, and is positioned between two contacting force absorbing members, distributing the shock force to the force absorption members, and supporting the device against slippage with respect to the force absorption members. Leaf spring tabs are formed within the cartridge shell, spaced from an edge of the cartridge shell to allow their flexure. The force absorption members are positioned between the device and the leaf spring tabs, contacting the tabs, such that the tabs assist in absorbing shock force directed at the leaf spring tabs.

Abstract: An electrical connection of a transfer station releasably, repeatably electrically couples with respect to a matching connection of a portable cartridge. A substrate in the portable cartridge has electrical contacts on a facing surface. In the transfer station, a matching circuitized flexible substrate has electrical contacts on a facing surface thereof, which are arranged to match the portable cartridge electrical contacts when in a face-to-face relationship. An elastomeric compression element, at the rear of the matching substrate, has individual protruding compression members contacting the rear surface and registered with corresponding individual electrical contacts. Elongated electrical contacts are registered with two adjacent individual compression members.

Abstract: A method and system to verify the passage of one or more write commands sent from an originating location through a PCI bus system. An addressable data storage is located substantially at the end of the PCI bus system with respect to the originating location. A write command is sent by the originator subsequent to the one or more write commands, to a predetermined special end location address identifying the addressable storage. The command is accompanied by data comprising a predetermined special return address at the originating location. The PCI bus system transmits the write commands on a FIFO basis, so the one or more write commands precede the subsequently sent write command. Logic senses the subsequently sent write command, and responds to the command, sending a return echo write command to the predetermined special return address. The returning echo write command verifies the passage of the write commands and data through the PCI bus system.

Abstract: A system and method for precisely registering and synchronizing data sets on a recording media having a prerecorded servo pattern. The recording media is subject to continuing movement for reading and/or writing the data sets, interrupted by stopping at the end of a selected data set and restarting. During the continuing movement of the recording media, a detector coupled to the servo system continuously reads linear position registration data modulated into the prerecorded servo pattern. An interpolator interpolates the prerecorded registration data to provide precision registration information for the data sets. Upon the drive stopping the recording media, then back hitching the media and the movement restarting, selected read and interpolated registration information is provided.

Abstract: In a PCI bus system, a method and system check for errors in rite data transferred from a PCI data source across a PCI bus to the PCI bus system, the data comprising a plurality of blocks. Redundancy calculation logic receives the write data across the PCI bus, calculates a check value for each block of the data transferred across the PCI bus, and updating any previously calculated check value with the calculated check value at a storage location of a storage memory. Data path logic is coupled to the PCI bus and to the storage memory, and responds to a unique identifier of a redundancy write command sent subsequent to completion of the transfer of the write data across the PCI interface. The data path logic responds to the write command unique identifier, detecting the updated calculated check value at the storage location of the storage memory.

Abstract: A servo position detector and a method for detecting and following an index position displaced at an offset with respect to an edge of a servo track, an edge comprising an interface between two dissimilar recorded servo signals. The servo track has two edges on opposite lateral sides of a middle recorded servo signal, the edges separated by a predetermined distance. A servo read element has an active sensing region which is no more than and is substantially the entire predetermined distance separating the edges, thereby.sensing no more than two of the dissimilar recorded servo signals at one of the edges. An independent position sensor senses the coarse position of the servo read element, indicating which edge or which index position is aligned with the servo read element. Logic compares the two sensed servo signals to determine the ratio therebetween, and determines an error between the compared ratio and a predetermined ratio.

Abstract: A maximum likelihood detector and a method for maximum likelihood detection of digital samples of channel output of data recorded as analog signals representing a finite number of states. The method comprises, first, programming at least two numerical metric coefficients. The coefficients are respectively applied to each sequential digital sample to generate alternative metrics, and each respective alternative metric is compared to a previous metric based on a previous digital sample. Based on the comparison, one of a plurality of provided metrics is selected which minimizes the mean squared error with respect to the previous metric. Then, the one of the finite number of states represented by the selected metric is identified, and a maximum likelihood path memory is set to a maximum likelihood state dictated by the identified one of the finite states, thereby detecting the recorded analog signals.

Abstract: Drive image providers of a virtualization system for an automated data storage library provide an image of a fixed plurality of virtual data storage drives with fixed identifications to a host application. A drive resource provider, at any one time, assigns any number “m” of a pool of “n” drives to the drive image providers, and “n”−“m” of the pool are freed and available for assignment. The drive resource provider responds to a triggering event requesting a drive, and dedicates one of the “n”−“m” drives of the pool to the virtual drive. The drive image provider characterizes and directs communication between the host and the dedicated drive as a fixed virtual drive; and prior to the dedication of a drive, characterizes the virtual drive to the requesting host application as “not ready”.

Abstract: An intelligent bus listening device, and a method which may be implemented as a computer program product, listens to SCSI commands on a first SCSI bus of a SCSI system via a listening connection to the first SCSI bus. The listening device is separately coupled via an interface to a second bus for communicating commands onto the second bus. A processor is coupled to the listening connection and to the second bus interface, the processor receiving the first commands from the first SCSI bus, converting the first commands to second commands related to the first commands, and providing the second commands to the second bus interface.

Abstract: Disclosed are a data storage library and library computer processor implemented methods for expiring logical volumes in response to expiration selection from a host. A library server maintains a mapping database which identifies each logical volume and maps the logical volumes to data storage media. A library manager classifies the host selected expired logical volume in a category of logical volumes having a “SCRATCH” attribute, which may have an expiration delay, and identifies the selected logical volume in a searchable database as comprising the category having the “SCRATCH” attribute, and may calculate an expiration time for the selected logical volume from the delay. The library manager subsequently searches the searchable database for logical volumes identified as comprising a category having the “SCRATCH” attribute, and whose expiration time has passed, providing an indication to the library server that the searched identified logical volumes are expired.