Patent ID: 7630158
Filing Date: 2009-12-08
Classification: G11B

Abstract:
1. A media storage device, comprising: a head which reads and writes data from and to a storage medium which magnetically stores data; a channel circuit which demodulates read data from said head and having a maximum-likelihood decoder which calculates a number of times that cumulative sum of errors between ideal values and the read data exceeds a prescribed value from the context of stated transitions which are possible for the read data and detects data series of which the number of times is small, as a most probable data series; a control circuit which controls read and write operations of said head according to commands from a higher-level device; and a table which holds storage area information of each record, in record units of said storage medium wherein said control circuit stores said storage area information of said record in said table when receiving a write command, reads, via the channel circuit, data recorded on the storage medium in record units by referring to said table during idle time of which a command has not arrived at a predetermined time from said higher-level device, measures said number of times detected by the maximum-likelihood decoder during reading, compares the measured number of times with a prescribed threshold value, and depending on the result of the comparison, re-records said data in record units in the storage medium.