Method and device for establishing magnetic disk null cluster table and seeking magnetic disk null cluster

Abstract

The invention discloses a method and a device for building an empty cluster table of a disk. The method includes: setting at least two recording items in a file allocation table FAT used for marking whether the corresponding cluster in the disk is an empty cluster or not as FAT sections which are continuous; building the empty cluster which includes the table items corresponding to the FAT sectionone by one; the table item value of the table item marks whether the corresponding FAT sections include the recording item for marking the empty cluster. The invention also discloses a method and a device for searching the empty cluster of the disk based on the built empty cluster table. The method includes: when the data are written, the corresponding sections that contain the recording items for marking the empty cluster are confirmed by checking the table item value which is in the empty cluster table and marks that the corresponding FAT sections contain the recording items for marking theempty cluster; Through the confirmed the recording items in the FAT sections, the corresponding empty cluster in the disk is searched. The method and the device of the invention can be adopted to notonly save the storage space, but also ensure the speed to write the data.

Description

technical field [0001] The invention relates to disk reading and writing technology, in particular to a method and a device for establishing a disk empty cluster table and searching for disk empty clusters. Background technique [0002] A disk is a storage medium, and a file allocation table (FAT, File Allocation Table) is a chained format used for indexing and locating disk data. After the disk is FAT-formatted according to the existing spec specification defined by Microsoft, the disk space can be divided into sectors, and each sector is usually 512 bytes. [0003] After FAT formatting, the basic organizational form of the disk can include: boot area (the size is 1 sector), FAT (the number of sectors included is determined according to the actual situation) and data area (the number of sectors included is determined according to the actual situation) . [0004] Depending on the specific FAT format, different areas such as the root folder may be added to the above-mention...

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Problems solved by technology

[0016] Obviously, compared with the first method, the above-mentioned second method saves the step of reading the FAT from the disk into the memory and then sequentially checking the value of the record items when writing data, and can directly use the data in the memory empty cluster table. Table item values ​​look for empty clusters, which makes writing data faster, but it takes a long time to obtain the distribution information of empty clusters on the disk in the preparation stage before writing data, and the empty cluster table will occupy the memory space of the system where the disk is located , for a large-capacity disk with a large number of clusters, it takes a long time and takes up a large memory space, which is impossible for a small-memory system

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