KR20130092737A - Method, system and computer-readable recording medium for searching position of metadata - Google Patents

Abstract

PURPOSE: A method, a system, and a computer-readable recording medium for searching the position of metadata are provided to find out the position of metadata through a single access to a storage medium, thereby using a maximum performance of a rapid storage medium. CONSTITUTION: A storage device (420) has a metadata area for storing metadata of a file. A file system (410) performs hashing of a specific file based on file name or file path of the specific file, obtains an address of the metadata of the specific file, and performs metadata read or write of the specific file at the address of the metadata area. The file system performs a first hashing that receives the file name or the file path as an input and outputs a hash key and a second hashing that receives the hash key as an input and outputs the address. [Reference numerals] (410) File system; (420) Storage device

Description

METHOD, SYSTEM AND COMPUTER-READABLE RECORDING MEDIUM FOR SEARCHING POSITION OF METADATA}

The present invention relates to a method, a system, and a computer-readable recording medium for performing data input / output through multiple paths, and more particularly, by performing hashing based on a file name or a file path to obtain an address of metadata. The present invention relates to a method, a system, and a computer-readable recording medium for obtaining location information of metadata for a specific file with only one access.

Recently, devices that store data on a high speed storage medium and execute the stored data have been commercialized. In order to perform reading or writing of specific data in a storage medium, a logical position of the specific data must be known.

The file system assigns a unique name to each file and determines the location of those files for storage or retrieval of the file. In particular, when using a flash memory or the like as a storage medium, the file system stores the file and the data contained in the file, and manages the file and the data so that the file and the data can be easily retrieved.

Various methods are currently introduced to speed up the retrieval of data. In particular, technologies for improving the retrieval speed of data using metadata have been developed. Metadata is information about a specific file and is data describing the attributes of the file. That is, metadata is not data actually executed but provides information directly or indirectly associated with the data. In the case of building a file system using such metadata, data management efficiency is improved.

However, even if such a metadata can be used to improve the management efficiency of the file, when a read or write request for a specific file occurs, the location of the metadata must be found.

In the past, a method of retrieving metadata of a specific file using a directory structure has been widely used. However, the number of accesses to the storage medium increases for reading files existing in subdirectories. Therefore, there is a problem in that the performance of a high performance storage medium cannot be used to the maximum.

Korean Patent Publication No. 10-2004-0010314 (published: January 31, 2004)

SUMMARY OF THE INVENTION The present invention has been made to solve all the problems of the prior art described above.

It is an object of the present invention to be able to find the metadata location of a particular file with only one access to the storage device.

According to an embodiment of the present invention, performing hashing based on at least one of a file name or a file path of a specific file to obtain an address for metadata of the file; And reading or writing the metadata of the file at a position corresponding to the address of the metadata area.

The address obtaining step may include: a first hashing step of outputting a hash key by inputting the file name or the file path; And a second hashing step of outputting the address by inputting the hash key.

The address obtaining step may further include performing at least one of double hashing or linear probing to avoid the collision when the second hashing result collision occurs. have.

The metadata location searching method may include, before the address obtaining step, hashing one or more files existing in a system based on at least one of a file name or a file path to designate an address where metadata of each file is to be stored. step; And storing metadata of each file at the designated address location of a metadata area.

On the other hand, according to another embodiment of the present invention, performing a hashing based on at least one of the file name or the file path of a specific file to obtain a hash key; And determining an address of the metadata of the specific file based on a table in which a correspondence between the address of the file and the hash key is stored.

The metadata location retrieval method may include obtaining a hash key for one or more files existing in a system before the hash key obtaining step; And creating the table storing the correspondence relationship between the metadata address of the one or more files and the hash key.

Furthermore, according to another embodiment of the present invention, there is provided a storage device having a metadata area for storing metadata of any file; And hashing based on at least one of a file name or a file path of a specific file to obtain an address for the metadata of the specific file, reading the metadata of the specific file at the address location of the metadata area, or A metadata location retrieval system is provided that includes a file system for writing.

The file system may perform first hashing to output a hash key by inputting the file name or file path, and second hashing to output the address by inputting the hash key.

The file system may further perform at least one of double hashing or linear probing when a collision occurs as a result of the second hashing.

The file system may designate an address to store metadata of each file by performing hashing on at least one file existing in the system based on at least one of a file name or a file path.

According to another embodiment of the present invention, there is provided a storage device including: a storage device having a metadata area for storing metadata of any file; And obtaining a hash key by performing hashing based on at least one of a file name or a file path of the specific file, and based on a table in which a correspondence between the address of the file's metadata and the hash key is stored, A metadata location retrieval system is provided that includes a file system for resolving addresses for data.

The file system can obtain a hash key for one or more files present in the system and create the table that stores the correspondence between the metadata addresses of the one or more files and the hash key.

According to still another embodiment of the present invention, there is provided another method for locating metadata with only one access through a hash key generation method, and a computer readable recording medium for recording a computer program for executing the method. Is provided.

According to the present invention, by identifying a metadata position in a metadata area using a hashing process, or by managing a table for a correspondence between a hashing key obtained by the hashing process and an address of metadata, Metadata locations can be located with only one access, thereby maximizing the performance of high-speed storage media.

1 is a diagram illustrating a general metadata retrieval method.
2A to 2C are flowcharts illustrating a metadata location search method according to a first embodiment of the present invention.
3A and 3B are flowcharts illustrating a metadata location search method according to a second embodiment of the present invention.
4 is a diagram illustrating a configuration of a system for performing metadata location search according to an embodiment of the present invention.
5 is a diagram schematically illustrating a method of searching metadata for a specific file according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

[Preferred Embodiment of the Present Invention]

1 is a view for explaining a method of finding the metadata location of a specific file in a general file system.

Referring to FIG. 1, in a typical file system, a directory structure is used to find a metadata location.

For example, to find the metadata location of a specific file with a file name or file path of "A / B / C / D / E", look for a directory named "B" under the directory "A", and in the hierarchy below Again, directories of "C" and "D" are sequentially found, and then metadata of "E" is found under the directory of "D".

Metadata retrieval using such a directory structure increases the number of times of access to a target storage device.

2A to 2C are flowcharts illustrating a metadata location search method according to a first embodiment of the present invention.

Referring to FIG. 2A, first, an address of metadata of each file is designated (S210).

FIG. 2B is a flowchart for describing an operation performed in step S210 of FIG. 2A. As described above, in step S210, an operation for specifying an address of metadata of each file is performed.

Referring to FIG. 2B, a hash key is generated based on at least one of a name of a specific file or a physical location of the file (S211). Hereinafter, the hashing performed in step S211 is referred to as first hashing. The physical location of a file can be the path of that file in the directory structure or the file search. In a file system of a typical operating system (e.g., Linux), the name of a particular file or the physical location of that file is unique to a particular file. Thus, the hash key for each file can be formed differently. A hash function may be used to generate a hash key, where a hash function may be used. For example, a hash function such as Secure Hash Algorithm-1 (SHA-1) may be used, but a different hash function may be used. If SHA-1 is used as a hash function, a string having a length of 160 bits is obtained as a hash key for each file.

When the hash key is obtained, hashing is performed once more on the hash key to designate an address in the metadata area (S212). The hashing performed in step S212 may be referred to as a second hashing.

The metadata area may have at least as many address areas as the number of files. For example, it may have an address area from 0 to N. Additional hashing can be performed to assign the hash key to the metadata area. A second hashing is performed based on the hash key obtained in step S211 to obtain an address value in the metadata area. Assuming that the metadata area may have an address value from 0 to N, the value obtained by the second hashing may be a value between 0 and N. However, if the same value among the values from 0 to N is hashed as a result or clustered at one position, that is, collision may occur. At this time, a method for avoiding such a collision can be used. For example, a double hashing or linear probing method can be used.

In case of collision, double hashing is a method of additional hashing using another hash function. In case of collision, linear search moves from the current address to the next address with a predetermined width.

If an address is specified in the metadata area according to this process, the metadata of the file is located at the address.

Referring again to FIG. 2A, when a read or write request for a specific file occurs (S220), the location of metadata is found based on the address specified in step S210 (S230).

2C is a flowchart for explaining an operation performed in step S230.

Referring to FIG. 2C, a hash key is obtained by performing first hashing based on one of a file name and a file path of a corresponding file (S231). The hash function used at this time may be the same as the hash function used in step S211. Next, second hashing is performed based on the hash key obtained as a result of the first hashing to obtain a value corresponding to an address in the metadata area (S232). By doing this, the metadata location of the file can be determined. You can find the location of the target file from the metadata.

If the current command is a write command for a specific file, the following process may be further performed. There may be a case where the address obtained as a result of performing step S232 is already occupied, and at this time, the collision avoidance method described above is performed (S233). In this way, the free area may be found and the metadata of the file requested to be written to the corresponding location may be input (S234).

Hereinafter, a metadata location search method according to a second embodiment of the present invention will be described.

3A to 3B are flowcharts illustrating a metadata location search method according to a second embodiment of the present invention.

Referring to FIG. 3A, a table showing a correspondence relationship between a hash key and a metadata area for each file is first created (S310).

3B is a diagram illustrating an operation performed in step S310. Referring to FIG. 3B, a hash key is generated based on at least one of a name of a specific file or a physical location of the file (S311). Since the hashing process of step S311 is the same as the first hashing process described with reference to FIG. 2B, a detailed description thereof will be omitted.

After generating the hash key, a table is stored to store the correspondence between the hash key and the address of the metadata area in which the metadata of the file is stored (S312). The metadata for each file is stored in the metadata area, and an address is assigned to each location where the metadata is stored, and the corresponding information between the address of the metadata and the hash key generated in step S311 is stored and managed as a table. .

Referring again to FIG. 3A, when a read or write request for specific data occurs (S320), the metadata location of the corresponding file is found based on the table generated in step S310 (S330). Since the hash key of each file is unique, if the information on the hash key of each file is known, the address of the metadata can be grasped based on the table generated in step S310. Based on this address, the metadata of the file can be found in the metadata area, and the location of the target file can be found from this metadata.

4 is a diagram illustrating a configuration of a system for performing metadata location search according to an embodiment of the present invention.

Referring to FIG. 4, the system of the present invention may include a file system 410 and a storage device 420.

The file system 410 according to an embodiment of the present invention assigns an address to metadata of each file existing in the system. Specifically, after hashing to obtain an address value in the metadata area, metadata of each file is stored at the corresponding address. That is, the operation of step S210 described with reference to FIGS. 2A and 2B is performed. Further, according to another embodiment of the present invention, the file system 410 performs a hashing based on at least one of the file name or the file path of each file to obtain a hash key and map it to the metadata address of the file. Write. That is, the operation of step S310 described with reference to FIGS. 3A and 3B is performed.

On the other hand, the file system 410 locates the file in response to a file read or write request generated by the operating system. The file system 410 according to an embodiment of the present invention finds the metadata location of the target file that is requested to be read or written, and finds the location of the file based on the file location. The metadata location may be determined based on the address specified in step S210 described with reference to FIGS. 2A and 2B or the table generated in step S310. In general, the file system 410 may execute each operation described with reference to FIGS. 2A through 2C, 3A, and 3B.

The storage device 420 according to an embodiment of the present invention stores each file existing in the system and metadata corresponding to the file. That is, the storage device 420 has a metadata area in which metadata is stored. Storage device 420 is a conventional storage medium, for example, magnetic media such as hard disks, floppy disks, and magnetic tape, optical recording media such as CD-ROMs, DVDs, magnetic disks such as floppy disks, and the like. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Also, other high performance storage media may be used, such as hardware devices such as flash SSDs and DRAM SSDs. However, this is only one example, and of course other storage devices can be used as the storage device 420 of the present invention.

5 is a diagram schematically illustrating a method of searching metadata for a specific file according to an embodiment of the present invention.

For example, if you want to find the metadata of a file having a file name or file path of "A / B / C / D / E", hashing the file name or file path is performed so that the address in the metadata area can be found. You can get this and find the metadata directly. That is, compared to FIG. 1, the metadata location for a specific file can be found by only one direct access to the metadata area without using a directory structure.

The embodiments of the present invention described above can be implemented in the form of program instructions that can be executed through various computer components and recorded on a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination. Program instructions recorded on the computer-readable recording medium may be those specially designed and configured for the present invention, or may be known and available to those skilled in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs, DVDs, and magneto-optical media such as floptical disks. media), and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for performing the processing according to the present invention, and vice versa.

Although the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and the drawings are provided to assist in a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations can be made from these descriptions.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

410: file system
420: storage device

Claims (13)

Obtaining an address for metadata of the file by performing hashing based on at least one of a file name or a file path of a specific file; And
And reading or writing metadata of the file at a position corresponding to the address of a metadata area. The method of claim 1,
The address obtaining step,
A first hashing step of outputting a hash key by inputting the file name or file path; And
And a second hashing step of outputting the address by inputting the hash key. The method of claim 2,
The address obtaining step,
If a collision occurs as a result of the second hashing, performing at least one of double hashing or linear probing to avoid the collision. The method of claim 1,
Before the address acquisition step,
Hashing one or more files existing in the system based on at least one of a file name or a file path to specify an address where metadata of each file is to be stored; And
And storing the metadata of each file at the designated address location in a metadata area. Obtaining a hash key by performing hashing based on at least one of a file name or a file path of a specific file; And
And determining an address for the metadata of the specific file based on a table in which a correspondence between the address of the file and the hash key of the file is stored. The method of claim 5,
Before the hash key acquisition step,
Obtaining a hash key for one or more files present in the system; And
Creating the table storing the correspondence between the metadata address of the one or more files and the hash key. A storage device having a metadata area for storing metadata of any file; And
Hashing is performed based on at least one of a file name or a file path of a specific file to obtain an address for the metadata of the specific file, and reading or writing to the metadata of the specific file at the address location of the metadata area. Metadata location retrieval system including a file system for performing the. The method of claim 7, wherein
The file system comprises:
And a first hash to output a hash key by inputting the file name or file path, and a second hash to output the address by inputting the hash key. 9. The method of claim 8,
And the file system further performs at least one of double hashing or linear probing when a collision occurs as a result of the second hashing. The method of claim 7, wherein
And the file system hashes one or more files existing in the system based on at least one of a file name or a file path to specify an address where metadata of each file is to be stored. A storage device having a metadata area for storing metadata of any file; And
Hashing is performed based on at least one of a file name or a file path of a specific file to obtain a hash key, and based on a table in which a correspondence between the address of the file's metadata and the hash key is stored, the metadata of the specific file. A metadata location search system comprising a file system for identifying an address for a. 12. The method of claim 11,
And the file system obtains a hash key for one or more files present in the system and creates the table that stores the correspondence between the metadata addresses of the one or more files and the hash key. A computer-readable recording medium for recording a computer program for executing the method according to any one of claims 1 to 6.

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