Abstract: Provided is a method, system, and program for encoding and decoding input data. A key is generated comprising a list of a plurality of binary values, wherein the key is available to a user during decoding. The input data is encoded by using the key to initialize a replacement list. A determination is made whether to replace strings in the input data with a string reference to a matching string value, wherein the input data not replaced with reference to one matching string value comprises one or more literals. Each literal is replaced with a literal reference to one entry in the replacement list matching the literal. The encoded input data is decoded by accessing the generated key in response to user input and using the accessed key to decode the literals replaced with literal references to entries in the replacement list.

Abstract: In a tape having separate servo bands of patterns positioned laterally across the tape, the patterns of a separate servo band have at least one differentiating characteristic with respect to patterns of another of the separate servo bands. The differentiating characteristic allows identification of the separate servo bands. For example, the patterns of a separate servo band have differing azimuthal orientations of detectable transitions with respect to another servo band, such as being laterally inverted. In another, variations in the width of gaps of patterns are made with respect to another servo band. In another, variations are made in the number of the detectable transitions of patterns with respect to the patterns of another servo band.

Abstract: Provided is a method, system, and program for storing input groups of uncoded binary data on a storage medium. A plurality of uncoded data blocks in a data stream are received. An encoded data stream is obtained from concatenating successive encoded blocks such that the encoded data stream includes a predetermined bit pattern comprising a plurality of bits. The bit pattern always occurs within a first number of bits and two occurrences of a “1” or “0” occur within a second number of bits. The encoded data blocks are stored on the storage medium.

Abstract: A cartridge handling system and method initialize a data storage cartridge having rewritable media for tamper resistant write once recording. A write once flag is written to a lockable section of a cartridge memory; the lockable section is locked to read-only; and a write once flag is written to a required data set of the rewritable media. Thus, write once flags are provided both at the locked read-only section of the cartridge memory, and at the required data set of the rewritable media.

Abstract: A recording system of a magnetic tape drive is operated to cause one separate set of write heads to write data discontinuously to magnetic tape as received, and to save the data, and, during the same operation, to cause another separate set of write heads to rewrite data to magnetic tape in a continuous arrangement. The writing may be in parallel and simultaneous. Thus, during the same operation, and at the same time, the separate sets of the plurality of write heads, temporarily write the received data to magnetic tape so that the sender can erase its copy, and rewrite the saved data to the magnetic tape in a permanent arrangement, without waiting to complete first writing received data, to complete subsequently rewriting the data, and repeating.

Abstract: In a magnetic tape drive having a plurality of stepped operational speeds, data storage logic estimates, from the effective data fill rate for a data buffer and the drive data write rate, the time cost to continue to operate the magnetic tape drive at the current stepped operational speed from a target to the next end of wrap; estimates, the time cost to force a backhitch of the magnetic tape data storage media and change the stepped operational speed to a higher stepped operational speed and operate the magnetic tape drive at the higher stepped operational speed to the next end of wrap; and determines the lesser time cost.

Abstract: 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).

Abstract: In a magnetic tape system, during lateral repositioning of a tape head between servo bands, the servo head is not on a servo band and is unable to provide servo position information. Hence, information about the lateral position may be lost. A control system selectively senses data read transducers of the tape head; and, upon detecting a servo signal of a servo band from a sensed data read transducer, determines the lateral position of the tape head with respect to the detected servo band based upon the position of the data read transducer that sensed the detected servo signal.

Abstract: Provided is a method, system, and program for storing data in a storage medium. A layout of a storage medium including a first and second user data sections is provided, wherein the first user data section comprises a faster access storage space than the second user data section. A determination is made of a first set of data to be accessed with less delay than a second set of data. The first set of data is written to the first user data section and the second set of data is written to the second user data section.

Abstract: In magnetic tape having separate longitudinal servo bands of servo information with superimposed data information, the separate servo bands have selected different superimposed data information, to identify the separate servo bands for independent addressability. The servo information comprises non-parallel laterally extending transitions to indicate lateral positioning, and the selected different superimposed data information may comprise a lack thereof in portion(s) of the servo bands. Where the superimposed data information is longitudinal position information of the tape, the selected different superimposed data information may comprise different longitudinal position information of one or more servo band(s). The selected different superimposed data information may comprise a band identifier in the superimposed data information of one or more of the servo bands.

Abstract: Special fields for error recovery are provided in data set information tables of data sets written with synchronized transactions. If a transaction only partially fills a data set, that data set is rewritten in a succeeding data set, appending the next transaction. A moving access point in the table identifies the appended transaction, allowing the rewritten transaction to be skipped during read recovery. The table provides recovery trails by providing a thread to tie the data sets together, the status of the data set, and pointers, such as identifying the wrap of the immediately succeeding data set.

Abstract: Synchronized data is written to magnetic tape while reducing the number of backhitches. A controller detects a pattern of synchronizing events for received data records to be written to tape; writes each transaction of data records to the magnetic tape; accumulates the synchronized transactions in a buffer; and subsequently recursively writes the accumulated transactions of data records from the buffer to the magnetic tape in a sequence. A single backhitch may be employed to place the recursively written accumulated data records following the preceding data, maximizing performance and capacity.

Abstract: Data of a transaction to be synchronized is stored to a non-volatile store, and a Command Complete response is provided. Data of the transaction is supplied to a tape drive for writing to a magnetic tape. The storing, responding, and supplying operations are repeated for subsequent transactions. A Deferred Synchronize Command, specifying a previously supplied transaction, is provided to the tape drive, for writing data of the specified transaction. The tape drive, subsequent to writing all the data of the previously supplied transaction to magnetic tape, provides a Tape Command Complete, whereupon the data of the previously supplied transaction stored to the non-volatile store may be overwritten.

Abstract: Authentication of an upgrade to computer readable program code of a target embedded device is accomplished by causing the computer processor of the embedded device to access an unique machine identifier; to access an identifier key associated with the upgrade; to process the identifier key and/or unique machine identifier, such as by decrypting the key and/or encrypting the identifier; to compare the identifier key with the unique machine identifier; and causing the computer processor, if the identifier key matches the unique machine identifier, to enable the upgrade; else, to fail the upgrade.

Abstract: A sequential buffer for a magnetic tape data storage system comprises a plurality of segments. A buffer management system buffers data in the sequential buffer, conducting a data transfer process. Subsequently, some of the buffered data is maintained in some, but less than all, the segments of the buffer. Additionally, the maintained buffered data is indicated as VALID data. Thus, a subsequent process may be conducted directly using the data maintained in the buffer, and avoids moving the tape to reread the data.

Abstract: A cartridge handling system and method initialize a data storage cartridge having rewritable media for tamper resistant write once recording. A write once flag is written to a lockable section of a cartridge memory; the lockable section is locked to read-only; and a write once flag is written to a required data set of the rewritable media. Thus, write once flags are provided both at the locked read-only section of the cartridge memory, and at the required data set of the rewritable media.

Abstract: Authentication of an upgrade to computer readable program code of a target embedded device is accomplished by causing the computer processor of the embedded device to access an unique machine identifier; to access an identifier key associated with the upgrade; to process the identifier key and/or unique machine identifier, such as by decrypting the key and/or encrypting the identifier; to compare the identifier key with the unique machine identifier; and causing the computer processor, if the identifier key matches the unique machine identifier, to enable the upgrade; else, to fail the upgrade.

Abstract: A source data stream is distributed to two or more compression paths that provide a corresponding number of compressed data streams that are concurrently encoded onto a recording medium as a set of media tracks. In one embodiment, buffer space within each compression path is monitored and the source data stream is directed to a ‘starved’ compression path. Metadata is inserted into the compressed data streams to facilitate reconstruction of the source data stream from the compressed data streams. The source data stream may be reconstructed by concurrently decoding the media tracks, decompressing the compressed data streams to a corresponding set of decompressed data streams, and merging the decompressed streams into an output data stream as directed by the metadata. The present invention overcomes the bottlenecks and other issues previously associated with context-based compression within digital media recording systems.

Abstract: Provided are a method, system, and program for encoding data onto a storage medium. Host data is received and a plurality of device blocks are generated to include the host data. A directory is generated including entries for physical locations on the storage medium, wherein each entry identifies one device block at the physical location corresponding to the entry, and wherein the directory is used to access data on the storage medium. The directory entries are encoded in the device blocks written to the storage medium.

Abstract: Provided are a method, system and article of manufacture for writing on a storage media. Data is received from a host. A determination is made whether the received data can potentially form a trailer record on the storage media. If the received data does not potentially form the trailer record, then the received data is written to the storage media.