DIN EN 62842:2016-09

Hard disk and Blu-ray disc storage for home use to record television programmes are now standard. Normally a Hard Disk Recorder (HDR) is used for time shift and a Blu-ray Disc (BD) is used for library. When an HDR is used for time shift, television programmes are recorded and played, then many of them are deleted to reuse the spaces for other programmes to be recorded. These programmes are stored as files in a hard disk drive (HDD) using a file system. Continuous recording and deletion of programmes involves the continuous storing and deletion of files in the file system. Television programme streams include at least videos and an electronic programme guide (EPG). The HDR stores videos in a long, variable length file depending on the quality and recording hours. Compared with videos, EPG related information is stored in a shorter file or files but is often updated. This continuous creation, deletion and updating of files of different lengths finally causes the files to be stored in fragments, and the system performance becomes very low. In a computer, defragmentation tools are provided to solve the problem of a fragmented file system. Normally defragmentation with reallocation of files in sequence takes a long time and the end user cannot but wait for the completion of the defragmentation, with no other activity. In the home server environment, a smarter solution to resolve this problem needs to be provided. The recent newly developed HDD features will be reflected in the next version of the standard. The responsible committee is DKE/K 742 "Audio-, Video- und Multimediasysteme, -geräte und -komponenten" ("Audio, video and multimedia systems, equipment and components") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.