摘要:
A magnetic tape drive simultaneously senses on a magnetic tape three evenly spaced-apart servo track areas for servoing a multi-track magnetic head to follow a concurrent set of data tracks on the magnetic tape. The data tracks are arranged into a plurality of track groups. Each track group has a first and second subgroup of data tracks. The first subgroup of tracks are scanned in a first relative motion of the magnetic tape and magnetic head as a forward direction (tape is being spooled from a supply tape reel). The second subgroup of tracks are scanned in a second relative motion of the magnetic tape and magnetic head that is opposite in direction to the first relative direction and is a forward direction of scanning. While writing data in any one of the plural track groups, a servo dropout affecting most of the servo track areas is detected and indicated as a servo error. Writing is aborted. The relative position of the magnetic tape and head is detected at both longitudinal ends of the servo dropout. A servo dropout block (SDB), a tape control block, is written at each longitudinal end of the servo dropout only in the group of tracks in which data are being written. The tape space between the two SDBs is termed a limited portion of the tape in which no recording is permitted.
摘要:
A method and system are disclosed for efficiently reading and processing multiple data blocks stored in a removable data storage medium within a data storage system, wherein each data block includes a header portion containing selected parameters necessary to identify and process an associated data block, and a data portion. Each data block is accessed within the removable data storage medium utilizing track logic circuitry and then coupled to a data block buffer for temporary storage. A header processing logic circuit is interposed between the track logic circuitry and the data block buffer and is utilized to initiate processing of only the header portion of each data block prior to storage of the data block within the data block buffer. After completion of processing of the header portion of a data block and completion of storage of that data block within the data block buffer, the data block is efficiently processed utilizing selected parameters contained within the header portion. In this manner, data blocks may be efficiently transferred, processed or coupled to an error recovery procedure from the data block buffer without the delay associated with processing each header portion of a data block after storage of that data block within the data block buffer.
摘要:
A method to erase a magnetic tape, where the magnetic tape is first mounted in a magnetic tape in a tape drive, where that magnetic tape includes a physical beginning of tape (“PBOT”), a physical end of tape (“PEOT”), and information written thereon between the PBOT and the PEOT. The method then establishes one or more critical areas located on the magnetic tape, attempts to erase the information, and determines if each of the one or more critical areas have been erased. In the event each of said one or more critical areas have not been erased, Applicants' method provides an error message.
摘要:
A peripheral data storage system employing a data buffer connected to a plurality of data storage devices, such as tape recorders, dynamically reallocates data buffer storage segments among the various data storage devices. A normalized elapsed-time period is established based upon the number of accesses to the data storage devices. When the number of accesses reaches a threshold the need for dynamic reallocation is examined. During the elapsed-time period the system monitors which of the allocated buffer segments have any data transfer activity at all and also measures the intensity of the activity for the respective buffer segments. In a peripheral system, the intensity is indicated by the number of channel command retries submitted to a connected host processor for the respective allocated buffer segment. Based upon the allocation status of the buffer segments and intensity of activities of the respective buffer segments, the buffer allocations are selectively reallocated among the data storage devices.
摘要:
Data processing workloads are balanced between a plurality of data processing units, such as control units of a peripheral system, based upon tallies of data processing delays. The workloads are arranged in work allocations, such as assignment of peripheral devices to a control unit; a separate delay tally is kept for each work allocation along with a summation of all delays in each control unit. When a tally threshold in any data processing unit is exceeded, load balance is examined. Upon a predetermined imbalance, a work allocation having a delay tally equal to a mean value of the different delay summations is transferred to a data processing unit having a lower delay summation.
摘要:
In one embodiment, a system includes a processor, logic in the processor and/or memory configured to determine a physical position on a magnetic medium that corresponds to an end of encrypted data written over residual unencrypted data, and logic configured to store an indicator of the physical position on at least one of the magnetic medium and a memory coupled thereto. In another embodiment, a method includes determining a physical position on a magnetic medium that corresponds to an end of encrypted data written over residual unencrypted data, storing an indicator of the physical position on at least one of the magnetic medium and a memory coupled thereto.
摘要:
An adaptive data transfer channel providing means for a data management access method (AM) to define the channel subsystem data block transfer size and to transfer an extended data block (EDB) by a single channel transfer command to avoid repeated channel command word (CCW) command decode and status presentation operations. The adaptive scheme of this invention is transparent to the user and downwardly compatible with existing data record storage formats because it is independent of the user application program. The host software in the central processing complex (CPC) tests the peripheral data storage device (PDSD) to ensure compatibility with the EDB CCWs before selecting the channel program (CP) to be used for data block transfer in the subchannel. In the EDB format, the PDSD microcode permits the accumulation of logical data blocks (LDBs) from storage to form a single large EDB before transfer to the CPC responsive to a single transfer command. Conversely, the CPC can transfer a single EDB to the PDSD where it is parsed to form data records in an existing data record storage format, thus ensuring complete downward compatibility with existing data record storage formats.
摘要:
Information bearing signals are recorded in one of a plurality of record formats on one record medium, such as a magnetic tape, magnetic disk, optical disk, and the like. The format selected may be commanded or based upon record lengths, in bytes. When the record length equals or exceeds a predetermined number of bytes, then one record is recorded in each signal block of the record format. When the record length is less than the predetermined number, then a second format is used which inserts several of the records in one of the signal blocks. The signal block and its packets respectively contain indications of formats such that any one of several formats may be used on one record medium and in one signal block having a plurality of variable length packets. Logical indicators, such as format marks, tape marks, and the like, may separate formats used on the storage medium.
摘要:
Information bearing signals are recorded in one of a plurality of record formats on one record medium, such as a magnetic tape, magnetic disk, optical disk, and the like. The format selected may be commanded or based upon record lengths, in bytes. When the record length equals or exceeds a predetermined number of bytes, then one record is recorded in each signal block of the record format. When the record length is less than the predetermined number, then a second format is used which inserts several of the records in one of the signal blocks. The signal block and its packets respectively contain indications of formats such that any one of several formats may be used on one record medium and in one signal block having a plurality of variable length packets. Logical indicators, such as format marks, tape marks, and the like, may separate formats used on the storage medium.
摘要:
Information bearing signals are recorded in one of a plurality of record formats on one record medium, such as a magnetic tape, magnetic disk, optical disk, and the like. The format selected may be commanded or based upon record lengths, in bytes. When the record length equals or exceeds a predetermined number of bytes, then one record is recorded in each signal block of the record format. When the record length is less than the predetermined number, then a second format is used which inserts several of the records in one of the signal blocks. The signal block and its packets respectively contain indications of formats such that any one of several formats may be used on one record medium and in one signal block having a plurality of variable length packets. Logical indicators, such as format marks, tape marks, and the like, may separate formats used on the storage medium.