37results about "Moving record carriers backward/forward" patented technology

The present invention is made such that data in a buffer can be transferred even when read back commands are continuously issued so as to completely eliminate the need for a mechanical operation required for each data block in ROR processing, resulting in considerably reducing a processing time. For this purpose, a method of controlling a magnetic tape unit of the present invention includes the steps of, when the read back command is received from a host processor, reading plurality of data blocks, when a read position of an MTU meets a predetermined condition, reading in a forward direction a plurality of data blocks in the range between the position and a start position of the read back command so as to write the data blocks into the data buffer, storing read commands concerning the data blocks into a command queue in reverse order to how the data blocks are read, and thereafter, in response to a read command from the host processor, reading the data blocks in the data buffer in the order in which the read commands are arranged in the command queue so as to transfer the data blocks to the host processor after data expansion. Further, the invention is applied to a magnetic tape unit to write data compressed through, for example, an EDRC system onto a magnetic tape, and read the compressed data therefrom.

Backspacing over data to overwrite the data as recorded on magnetic tape is provided logically, rather than by causing a magnetic tape to drive to backhitch. The data is written to the magnetic tape as it was before it was logically changed in order to insure that the data is preserved on tape. Recovery of the data is from a succeeding data set which logically invalidates the original data by a superseding identifier. Control logic arranges data transactions for writing to magnetic tape as data sets; and, in response to backspace and overwrite commands, or when transactions are accumulated into a succeeding data set, rewrites the original transaction adjusted in accordance with the commands as a superseding data set downstream from the original transaction, logically invalidating the original transaction by setting a superseding identifier in the superseding data set(s).

A technique for reducing the access time in a storage system having serially accessible media. One or more duplicate copies of data are maintained at different offset locations on serial media. When a request is made to read the data, a determination is made as to which copy of the data—either the original data or one of the duplicate copies—will have the shortest access time for accessing the data. Generally, this would be the data copy that will be closest to the data transducer when the tape is positioned for access, such as a tape cartridge being loaded in a tape drive. Once the tape is ready to be accessed, the tape is positioned to access the copy of the data that is in closest linear proximity with the reading transducer. Thus, the copy of the data having the lowest access latency is chosen to satisfy the particular I / O request.

Methods, computer systems, and computer program products are provided for operating a tape drive comprising a tape medium with a plurality of record groups stored thereon. Access sequence for the plurality of record groups is provided. The tape medium is positioned for reading a record group in the access sequence before a seek command for the record group in the access sequence is received.

In one embodiment, a tape drive system includes a read channel configured for performing a portion of a data transfer operation, logic adapted for monitoring the data transfer operation for detecting one or more temps within a sliding window spanning a last group of datasets processed, logic adapted for measuring interference between first tier and second tier recovery methods based on the monitoring, logic adapted for setting a backhitch delay based on conditions relating to the interference of first tier and second tier recovery methods as it relates to a determined error burst, and logic adapted for performing a backhitch and altering at least one condition of the data transfer operation after the backhitch delay.

Methods, computer systems, and computer program products are provided for operating a tape drive comprising a tape medium with a plurality of record groups stored thereon. Access sequence for the plurality of record groups is provided. The tape medium is positioned for reading a record group in the access sequence before a seek command for the record group in the access sequence is received.

In one embodiment, a tape drive system includes a read channel configured for performing a portion of a data transfer operation, logic adapted for monitoring the data transfer operation for detecting one or more temps within a sliding window spanning a last group of datasets processed, logic adapted for measuring interference between first tier and second tier recovery methods based on the monitoring, logic adapted for setting a backhitch delay based on conditions relating to the interference of first tier and second tier recovery methods as it relates to a determined error burst, and logic adapted for performing a backhitch and altering at least one condition of the data transfer operation after the backhitch delay.

A recording and reproducing apparatus is disclosed in which video signal and indexing signal are separately recorded in video signal areas and subcode areas, respectively, of diagonal tracks formed on a tape by a rotating head. The apparatus has a tape driver for driving the tape, add / erase command keys for generating add / erase command to add / erase the indexing signal, an indexing signal control for setting and resetting the indexing signal, and a recording device for recording the video signal to the video signal area and, if any, the indexing signal to the subcode area of each track. An editing control is provided for controlling the indexing signal control in response to the add / erase command such that the indexing signal is first recorded as a reset state for a first predetermined amount and then recorded as a set state.

Handling a magnetic tape cartridge comprises the steps of reading cartridge mount information from the cartridge memory; determining from the cartridge mount information whether the present mount is the first mount of the magnetic tape cartridge; and if so, fast forward and rewind the magnetic tape of the magnetic tape cartridge, e.g., the fast forward is to end of tape (EOT) and the rewind is to beginning of tape (BOT). Alternatively, if the cartridge mount information indicates the present mount is the first mount of the magnetic tape cartridge; monitoring input / output with respect to the magnetic tape cartridge for write errors during the mount; determining whether the number of monitored write errors meets a predetermined threshold; and if so, fast forward and rewind the magnetic tape of the magnetic tape cartridge.

Provided are a device and method for controlling writing of data, whereby a target amount of data is written to a tape medium, said target amount being a nominal capacity minus an amount of capacity lost by not backhitching. In the provided tape drive controller (16), when a command processing unit (41) receives a synchronization command, a buffer management unit (42) hands over data from a buffer to a channel I / O unit (43), and a write to a tape finishes, a backhitch determination unit (44) then determines whether the following conditions are fulfilled: information indicating a high-data-rate mode is stored in a mode information storage unit (45); of a nominal capacity, it is possible to write a target amount of data to the tape, said target amount being stored in a target amount storage unit (46); and it is possible to read the written data at a target read-out data rate. An operation signal output unit (48) gives an instruction to backhitch only in the case in which it is determined that the aforementioned conditions are not fulfilled.

Method and apparatus is described for optimizing the design of products, such as but not limited to mechanical products, by simultaneously subjecting the products to multiple stimuli, such as but not limited to temperature, vibration, pressure, ultraviolet radiation, chemical exposure, humidity, mechanical cycling, and mechanical loading.

High performance is obtained without preventing achievement of a target read data rate.In a controller 16 of a tape drive, a command processing unit 41 receives a synchronization command, and a buffer management unit 42 passes data in a buffer to a channel input-output unit 43. Then, upon completion of writing the data to the tape, a backhitch determination unit 44 determines whether or not to execute backhitch. If it is determined that backhitch should be skipped, the speed determination unit 46 determines a tape speed that minimizes a sum of a time required to write data without backhitch within a range where a data amount of a monitor target is to be written in order to achieve a target read data rate, and a time required to write data with backhitch within the range. Then, an operation signal output unit 49 issues an instruction to change the tape speed to the determined tape speed after execution of backhitch.

The problem that a target stop position can not be searched accurately when videotaping is started midway on a blank videotape having no control signals thereon is solved as follows. In order to locate the target stop position while the counter display counts up or down as the tape is transported, the action to stop the tape is started when the counter display reads the same value as in the target stop position. Then, when the tape is reversed to offset the overrun due to inertia, the tape transport is controlled so that the reverse motion stops when a prescribed number of control signals have been detected and the display shows that the time required to reach the target stop position becomes a prescribed time or less. Consequently, the target stop position can be searched accurately, whether or not there are recorded control signals on the tape.

In one embodiment, a method includes detecting an error while writing data to a tape volume. The method further includes repositioning the tape volume for recovering from the error, and receiving, after the repositioning, at least a portion of the data for rewriting the at least a portion of the data to the tape volume. Further, the method includes determining, after the repositioning, a current position of the tape volume. Additionally, the method includes determining, based on the current position of the tape volume, whether the rewrite to the tape volume is allowed.

A system and method for automatically unthreading a tape. The system and method determine whether the drive being at the stop state could cause the tape sticking condition in future after a defined dwell time (e.g., 20 minutes). The tape sticking tends to increase with time and humidity. Moreover, it is known that worn tape is stickier than new tape. With a plurality of attempts (e.g., four attempts) of moving tape (e.g., every 5 minutes), the drive is able to identify whether the tape needs to be unthreaded. Such a system allows a tape drive to handle the tape in safety at severe condition for the sticking tape, and minimize the penalty for the response to the command in normal condition.

A system and method for automatically unthreading a tape. The system and method determine whether the drive being at the stop state could cause the tape sticking condition in future after a defined dwell time (e.g., 20 minutes). The tape sticking tends to increase with time and humidity. Moreover, it is known that worn tape is stickier than new tape. With a plurality of attempts (e.g., four attempts) of moving tape (e.g., every 5 minutes), the drive is able to identify whether the tape needs to be unthreaded. Such a system allows a tape drive to handle the tape in safety at severe condition for the sticking tape, and minimize the penalty for the response to the command in normal condition.

The present invention decreases the number of repositions during read back by making use of multiple read elements associated with each data track. Each of a plurality of sets of read electronics receives the read signal from either one or the other of the two read elements associated with each data track and converts the received read signal into read data. For each data track, control logic selects one of the two read elements as a source for output data. In response to a determination that a read error has occurred, the control logic selects the other of the two read elements as the source for output data. For each data track, one read element is offset relative to the other read element in an offset direction normal to the tape direction.

A control system and method for operating a system comprising a host computer, a buffer, a tape drive and a tape is provided. The method includes writing data to the tape while the tape is traveling at a first speed; stopping the tape; determining an optimum second speed to drive the tape to travel; and, thereafter driving the tape to travel at the second speed while writing data to the tape.

In one embodiment, a method includes acquiring actual position information from encoding on a magnetic medium, calculating estimated position information of the magnetic medium using a media thickness value, comparing the estimated position information with the position information acquired from encoding, determining whether an error between the estimated position information and the acquired position information is within a specified range, in response to determining that the error is within the specified range, storing the media thickness value to a memory, and in response to determining that the error is outside the specified range, changing the media thickness value. In another embodiment, an apparatus includes a controller and logic integrated with and / or executable by the controller, the logic being configured to cause the controller to perform the foregoing method.

A method for using magnetic tape having damaged areas is disclosed. The method may include writing data to streaming magnetic tape, determining if the data write was successful, and responding to an unsuccessful data write by interrupting the data writing and advancing the magnetic tape forward a predetermined distance. Additionally, the method may include attempting to write data at the next location on the magnetic tape and determining if the data write was successful. The method may further include repeating the steps of advancing the tape, attempting to write, and determining whether the data write was successful following any determination that an attempted data write was not successful. The method may include further include resuming writing data to streaming magnetic tape at a location where a data write is determined to be successful.

In one embodiment, a method includes acquiring, by the computer, position information from encoding on a magnetic medium, causing, by the computer, a reel around which the magnetic medium is wrapped to rotate a number of rotations, calculating, by the computer, an estimated thickness of the magnetic medium based on the position information, the number of rotations, and a pack radius of the magnetic medium on the reel, and causing to be stored, by the computer, the estimated thickness. In another embodiment, an apparatus includes a controller and logic integrated with and / or executable by the controller, the logic being configured to cause the controller to perform the foregoing method.

A method for a tape storage system to adaptively handle Space commands sent from a host computer system is disclosed. In response to a Space command from the host computer system, a determination is made as to whether or not the tape storage system is in a Read mode. If the tape storage system is in a Read mode, the estimated cost of performing a special read operation for the Space command is compared with the estimated cost of performing a normal space operation for the Space command. If the estimated cost for performing a special read operation is lower than the estimated cost for performing a normal space operation, then a special read operation is performed. But if estimated cost for performing a special read operation is higher than the estimated cost for performing a normal space operation, then a normal space operation is performed.

In a video tape recorder (VTR), the capstan draws the tape from which the video signal is reproduced in a forward direction. The following steps are used to control the capstan, applying a torque to the capstan in a backward direction for a first predetermined period of time. Applying a torque to the capstan in the forward direction for a second predetermined period of time and nullifying the motor current. This arrangement is particularly convenient for slow-motion and still-picture modes.