DIFFERENCE RECORDING APPARATUS HAVING A PROCESSING UNIT, RECORDING UNIT, LOG UPDATE SECTION, AND LOG COMPARATOR USING A CLASSIFICATION KEY IN A LOG OF INPUT DATA

A difference recording apparatus includes a log comparator, a processing unit, a recording unit, and a log update section. The log comparator detects a log difference by using a classification key in a log of input data. The processing unit restores the log by using difference data from the log comparator. The recording unit records the log restored by the processing unit. The log update section limits recording of a log of identical data in the recording unit within a unit time on the basis of the presence/absence of a difference detected by the log comparator and an upper limit of log acquisition.