# US 9,520,145 B2 · Magnetic tape rewind overwrite data protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,145 B2 - Document ID: US9520145B2 - Status: Granted - Kind: B2 - Application number: 14/839,843 - Filed: 2015-08-28 - Published: 2016-03-31 - Granted: 2016-12-13 - Earliest claimed: 2014-09-25 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Randolph E. Stiarwalt - Web page: https://patentgrep.com/patent/US9520145B2 ## CPC - G11B 5/00813: {magnetic tapes} - G11B 5/09: Digital recording - G11B 15/6885: {the cassettes being conveyed within a cassette storage location, e.g. within a storage bin or conveying by belt} - G11B 19/04: Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions - G11B 27/002: {Programmed access in sequence to a plurality of record carriers or indexed parts, e.g. tracks, thereof, e.g. for editing; (transfer of record carriers from magazine G11B15/68, G11B17/10; G11B17/22)} - G11B 27/032: on tapes (G11B27/036, G11B27/038 take precedence) - G11B 5/4893: {relative to moving tape} - G11B 2220/41: Flat as opposed to hierarchical combination, e.g. library of tapes or discs, CD changer, or groups of record carriers that together store one title - G11B 2220/90: Tape-like record carriers - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract A computer-implemented method for preventing overwriting of data, e.g., on a magnetic medium, includes receiving a write command to write to a magnetic tape. The current location of the magnetic tape is determined. A determination is also made as to whether data corresponding to the write command is at least one of: a size and type specified for a block at the current location. Execution of the write command is disallowed in response to determining that the data corresponding to the write command is not of the specified size and/or type. ## Claims ### Claim 1 A computer-implemented method, comprising: receiving a write command to write to a magnetic tape; determining a current location of the magnetic tape; determining whether data corresponding to the write command is at least one of: a size and type specified for a block at the current location; and disallowing execution of the write command in response to determining that the data corresponding to the write command is not of the specified size and/or type. ### Claim 2 (depends on 1) A computer-implemented method as recited in claim 1, wherein the type of the data corresponds to a volume identifier. ### Claim 3 (depends on 1) A computer-implemented method as recited in claim 1, wherein the size specified for the block is different than a size specified for a user data block. ### Claim 4 (depends on 1) A computer-implemented method as recited in claim 1, wherein the block is a first block on the tape. ### Claim 5 (depends on 1) A computer-implemented method as recited in claim 1, wherein execution of the write command is disallowed in response to determining that the data corresponding to the write command is not of the specified size and type. ### Claim 6 (depends on 1) A computer-implemented method as recited in claim 1, wherein the method is performed in a tape drive. ### Claim 7 (depends on 6) A computer-implemented method as recited in claim 6, wherein the write command is received from a first host, wherein the current location of the magnetic tape is at the block at a beginning of tape because of a rewind command received from a second host. ### Claim 8 A system, comprising: a processor and logic integrated with the processor, executable by the processor, or integrated with and executable by the processor, the logic being configured to: receive a write command to write to a magnetic tape; determine a current location of the magnetic tape; determine whether data corresponding to the write command is at least one of: a size and type specified for a block at the current location; and disallow execution of the write command in response to determining that the data corresponding to the write command is not of the specified size and/or type. ### Claim 9 (depends on 8) A system as recited in claim 8, wherein the type of the data corresponds to a volume identifier. ### Claim 10 (depends on 8) A system as recited in claim 8, wherein the size specified for the block is different than a size specified for a user data block. ### Claim 11 (depends on 8) A system as recited in claim 8, wherein the block is a first block on the tape. ### Claim 12 (depends on 8) A system as recited in claim 8, wherein execution of the write command is disallowed in response to determining that the data corresponding to the write command is not of the specified size and type. ### Claim 13 (depends on 8) A system as recited in claim 8, comprising a tape drive having or in communication with the processor. ### Claim 14 (depends on 13) A system as recited in claim 13, wherein the write command is received from a first host, wherein the current location of the magnetic tape is at the block at a beginning of tape because of a rewind command received from a second host. ### Claim 15 (depends on 8) A system as recited in claim 8, comprising: a drive mechanism for passing a magnetic medium over a magnetic head; and a controller electrically coupled to the magnetic head, the processor being part of the controller. ### Claim 16 A computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a controller to cause the controller to: receive, by the controller, a write command to write to a magnetic tape; determine, by the controller, a current location of the magnetic tape; determine, by the controller, whether data corresponding to the write command is at least one of: a size and type specified for a block at the current location; and disallow, by the controller, execution of the write command in response to determining that the data corresponding to the write command is not of the specified size and/or type. ### Claim 17 (depends on 16) A computer program product as recited in claim 16, wherein the type of the data corresponds to a volume identifier. ### Claim 18 (depends on 16) A computer program product as recited in claim 16, wherein the size specified for the block is different than a size specified for a user data block. ### Claim 19 (depends on 16) A computer program product as recited in claim 16, wherein the block is a first block on the tape. ### Claim 20 (depends on 16) A computer program product as recited in claim 16, wherein the write command is received from a first host, wherein the current location of the magnetic tape is at the block at a beginning of tape because of a rewind command received from a second host.