Abstract: According to one embodiment, a magnetic disk device includes a disk that includes a plurality of tracks, each track including a plurality of sectors for storing data, a head that is for writing data to the plurality of sectors and reading data from the plurality of sectors, and a controller. The controller is configured to determine that a first sector of the plurality of sectors is not able to be read and is a defective sector, determine that a second sector of the plurality of sectors is disposed along a line that extends through the first sector and a defective sector included in a first list of defective sectors, register the second sector in the first list of defective sectors, and reallocate an address corresponding to the second sector to a first alternative sector included on the disk.

Abstract: According to one embodiment, a magnetic disk device includes a disk that includes a plurality of tracks, each track including a plurality of sectors for storing data, a head that is for writing data to the plurality of sectors and reading data from the plurality of sectors, and a controller. The controller is configured to determine that a first sector of the plurality of sectors is not able to be read and is a defective sector, determine that a second sector of the plurality of sectors is disposed along a line that extends through the first sector and a defective sector included in a first list of defective sectors, register the second sector in the first list of defective sectors, and reallocate an address corresponding to the second sector to a first alternative sector included on the disk.

Abstract: A control device includes an acquisition section which acquires a reading signal from a head under plural heat amounts, an computation section which computes plural kinds of characteristic values representing characteristics of the reading signal for each of the plural generated heat amounts by using at least one kind of algorithm, a contact determination section which determines whether or not the head contacts the storage medium for each of the two or more kinds of characteristic values based on a change of the characteristic values for the generated heat amount, and an association determination section which determines an association of a distance between the head and the storage medium with the generated heat amount when determined that the head contacts the storage medium for any of the characteristic values as the generated heat amount when the head contacts the storage medium so that the is considered to be zero.

Abstract: A control device includes an acquisition section which acquires a reading signal from a head under plural heat amounts, an computation section which computes plural kinds of characteristic values representing characteristics of the reading signal for each of the plural generated heat amounts by using at least one kind of algorithm, a contact determination section which determines whether or not the head contacts the storage medium for each of the two or more kinds of characteristic values based on a change of the characteristic values for the generated heat amount, and an association determination section which determines an association of a distance between the head and the storage medium with the generated heat amount when determined that the head contacts the storage medium for any of the characteristic values as the generated heat amount when the head contacts the storage medium so that the is considered to be zero.

Abstract: According to one embodiment, an information storage device includes: a head reading user data and a start tag indicating a recording start position of the user data in each sector recorded on a medium, the user data and the start tag being read in order of the start tag and the user data; and a controller controlling the head to read a start tag recorded in a preceding sector arranged at a position to be read before a target sector with a movement of the medium, acquiring information on a recording start position of a user data recorded in the target sector based on the start tag read by the head and a relative positional relation between the preceding sector and the target sector, and controlling the head to read the user data recorded in the target sector.

Abstract: A control unit adjusts spacing between a head with a heater and a storage medium of a storage unit by controlling the power of the heater. The control unit measures first values of touchdown heater power at a first temperature set as the temperature condition. And the control unit estimates second values of the touchdown heater power at a temperature other than the first temperature set on the measurement of the first values, on the basis of a conversion equation. And the control unit determines heater power setting values to adjust the spacing between the head and the storage medium, for each of the sub-areas, on the basis of the first values and the second values.

Abstract: A disk apparatus writes and rewrites data in a storage disk and reads data from the storage disk. A disk controlling apparatus that controls the disk apparatus includes an environment information creating unit creates environment information that is related to an environment of the disk apparatus, a storing unit that appends the environment information to the data that is to be written to the storage disk, and a rewrite process determining unit determines whether to execute a rewrite process based on the environment information in the data read from the storage disk.

Abstract: A preamplifier receives a servo gate signal indicating whether magnetic information read out from a disk by a head is servo data for positioning-use or user data stored in a user area available for reading and writing of given data. In the preamplifier, a servo data gain and a user data gain are set in advance. Based on a received servo gate signal, the preamplifier changes the gain depending on whether the head outputs the servo data or the user data.

Abstract: A gain setting apparatus that externally performs setting of a magnetic disk apparatus before shipment causes a servo data gain setting unit to set a servo data gain for a preamplifier. The gain setting apparatus then causes a core deviation correction processor to set the servo data gain as a provisional user data gain, so as to perform core deviation correction for correcting positional misalignment between a read core and a write core. Further, the gain setting apparatus causes a user data gain setting unit to set the user data gain for the preamplifier.

Abstract: A gain controller changes a gain of a read amplifier depending on whether a head reads out servo data or user data. Further, a heater setting unit changes the temperature of a heater and a reading gain when detecting touchdown performed by the head. Accordingly, a dynamic range of AGC in a read-write channel is increased, so that error detection is prevented for touchdown that occurs because an AGC gain converged value remains at 0.

Abstract: A control unit adjusts spacing between a head with a heater and a storage medium of a storage unit by controlling power of the heater. The control unit measures first values of touchdown heater power at a first temperature set as temperature condition. And the control unit estimates second values of the touchdown heater power at a temperature other than the first temperature set on the measurement of the first values, on basis of a conversion equation. And the control unit determines heater power setting values to adjust the spacing between the head and the storage medium, for each of the sub-areas, on the basis of the first values and the second values.

Abstract: A plurality of recording media combined integrally having a plurality of recording surfaces; and a plurality sets of reading heads and writing heads, combined integrally, provided for the respective ones of the plurality of recording surfaces, are provided. Upon writing data on each recording medium with the writing head provided therefor, a writing position is controlled as a result of positioning information previously provided on the recording media including the recording medium other than the each recording medium being read with the reading heads provided therefor.

Abstract: A guarantee processing method guarantees the data of an adjacent track in the case of a write fault when there is a possibility of an off track write. Even if a write fault is detected or an offset read retry is successful, a rewrite for guaranteeing an adjacent track is not executed immediately. The possibility of an off track write is judged by the movement of the head, and only the sector which is difficult to read due to the off track write is rewritten.

Abstract: A disk apparatus writes and rewrites data in a storage disk and reads data from the storage disk. A disk controlling apparatus that controls the disk apparatus includes an environment information creating unit creates environment information that is related to an environment of the disk apparatus, a storing unit that appends the environment information to the data that is to be written to the storage disk, and a rewrite process determining unit determines whether to execute a rewrite process based on the environment information in the data read from the storage disk.

Abstract: A plurality of recording media combined integrally having a plurality of recording surfaces; and a plurality sets of reading heads and writing heads, combined integrally, provided for the respective ones of the plurality of recording surfaces, are provided. Upon writing data on each recording medium with the writing head provided therefor, a writing position is controlled as a result of positioning information previously provided on the recording media including the recording medium other than the each recording medium being read with the reading heads provided therefor.

Abstract: A guarantee processing method guarantees the data of an adjacent track in the case of a write fault, and guarantees the data only when there is the possibility of an off track write at a write fault. Even if a write fault is detected or if an offset read retry succeeded, a rewrite for guaranteeing an adjacent track is not executed immediately, but the possibility of an off track write is judged by the movement of the head, and if there is the possibility of an off track write, the sector which became difficult to be read due to the off track write is detected, and only that sector is rewritten.

Abstract: A storage device capable of avoiding write fault error or read error occurring immediately after switching from power save mode or migration mode to ordinary mode. By carrying out a dummy write/dummy read command when switching from power save mode for reducing electric power consumption or migration mode for reducing the time for which the electric current flows in magnetic heads, normal write command/read command is executed in a condition in which the magnetic heads are placed completely in on-track condition.

Abstract: (1) A polyvinyl alcohol derivative represented by the formula: ##STR1## (where R.sub.1 is a hydrogen atom or an alkyl group, R.sub.2 is an aryl group, and k, l, m, and n denote integers of 1 or more.) (2) A photosensitive material for photomechanical process containing a polyvinyl alcohol derivative represented by the formula: ##STR2## (where R.sub.1 is a hydrogen atom or an alkyl group, R.sub.2 is an aryl group, and k, l, m, and n denote integers of 1 or more) and a sensitizing agent.