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A method for saving partial index of file system by volume of changes

IP.com Disclosure Number: IPCOM000235608D
Publication Date: 2014-Mar-12
Document File: 2 page(s) / 32K

Publishing Venue

The IP.com Prior Art Database

Abstract

An improved data processing apparatus and mechanism to write to tape medium only partial index including updated part when the fixed ammount of updates are heaped in order to decrease and level writing time of index

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A method for saving partial index of file system by volume of changes

An improved data processing apparatus and mechanism to write to tape medium only partial index including updated part when the fixed ammount of updates are heaped in order to decrease and level writing time of index

Disclosed is a method for decreasing writing time of index (File Allocation Table) of LTFS (Linear Tape File System).

There is a method for using a tape medium (a tape cartridge or medium) via a file system as if the tape medium is a HDD or a USB memory. For example, a linear tape file system (LTFS) manages a tape medium split into two areas called a data partition (DP) and an index partition (IP). The LTFS stores the main body of a file in the DP of a tape medium and also stores metadata on the file, called an index, such as a file name or an ID for identifying the file, in the IP of the tape medium in an extensible markup language (XML) file format. The index includes metadata on all of files stored in a single tape medium. The present LTFS format is not permitted to divide an index into a plurality of XML files. The task of storing an index on the tape medium is referred to as a synchronization or "sync" task or operation at mounting a tape medium. A user can select the timing of the execution of the sync operation by configuring the settings at the time of the startup of the LTFS system. Examples of the timing of the execution of a sync operation include periodical execution, execution at the time of the closing of a file, and execution at the time of the unmounting, or dismounting, of a tape medium.

In LTFS, before reading or writing files on a tape medium, the tape medium is necessary to be formatted with LTFS format. The LTFS format is a self-describing tape format developed by International Business Machines (IBM) Corporation of Armonk, New York and published. As mentioned above, LTFS utilizes a tape medium by splitting two partitions, DP and IP. When user writes a file to a tape medium via LTFS, main body and metadata of the file is written to DP and metadata of the file written in IP. IP has the latest metadata of all files and DP has main body of all files and history of metadata.

Fig.1 shows that data location on tape medium initialized by LTFS format.

FID (Format Identification Data set) is a special data located at the top of tape medium when formatting by tape drive. It has the information of number of partitions and their capacity.

VOL1 Label is a general format label defined by ANSI...