KR20030071245A - Store system and method of dynamic bitmap for huge file system - Google Patents

Abstract

PURPOSE: A mass file storage system and a dynamic bitmap management method are provided to dynamically allocate a bit map without being restricted by a file size so that it can effectively manage large sized files. CONSTITUTION: The method comprises several steps. A bit map is read from a storage device(S521). A pattern value is read from the header of the bit map in order to be compared with an object pattern requested by a file system(S522). If the pattern of the bit map is identical to that of the object pattern, the number of used bits is compared with that of the total bits(S523). If the number of the used bits is less than that of the total bits, unused bits are set with "1"(S524). Then, a bit map area is allocated to a corresponding object(S525). If the pattern of the bit map is not identical to that of the object or the number of the used bits is more than that of the total bits, it is checked whether there is a bit map in use allocated at a current bit map area(S526). If there is a bit map in use, a new bit map is read, otherwise an unused bit map is selected from a bit map area and is set with a requested pattern(S527). Then, the first bit of the new allocated bit map is set with "1" for allocating a bit map area to the object(S528).

Description

Storage system and method of dynamic bitmap for huge file system using large file storage system

The present invention relates to a large file storage system and a method for managing a dynamic bitmap of a large file using the same, and particularly, to a bitmap for managing an inode, a directory entry, and a data block, which are objects for managing a file in a large file storage system. It relates to the composition and allocation and retrieval method of the. That is, according to the present invention, a method of constructing a bitmap for the entire disk space allocated to a large file system, and using the same, dynamically manages three objects using a bitmap when an operation on the file system occurs. The present invention relates to a method for efficiently managing a bitmap according to an object, to minimizing waste of storage space such as a disk, and to a computer-readable recording medium having recorded thereon a program for realizing the method.

Research on file storage systems has been ongoing since the computer was first developed and many products have been released. The Unix file system (UFS), the Linux file system (Ext), and the Windows file system (NTFS) are some examples.

In such a file system, in order to store and manage files in a storage device such as a disk or a CD-ROM, an inode for managing information about a file, a directory entry for managing directory information, which is a collection of files, and contents of an actual file are stored. Data blocks need to be managed effectively. To do this, in UNIX or Linux file systems, when creating a file system, the storage space is divided into three areas: inode, directory entry, and data block. To manage this, the bitmap area corresponding to each object is statically managed. Use techniques to allocate and manage

If 1 bit of bitmap is allocated and used for each object, it is set to 1, otherwise it is set to 0.

The size of the file stored in the file system is important to determine the size of the area and bitmap for the object. If you have 100GB of data and 1MB of file size, you can store 100,000 files in the file system, so allocate an area for 100,000 inodes, and save 100,000 bits. This is done by setting the node bitmap area. However, due to the large variety of file sizes, it is difficult to set up an exact sized bitmap area, so Unix or Linux file systems allocate one inode per 4KB.

However, this static bitmap method has two problems.

First, when the size of a file stored in the file system is small, in a file system using a static bitmap, if the size of the stored file is small, the number of inodes is insufficient, which causes a waste of storage space. In other words, if a file size of less than 4KB occurs in the file system, there is a space in the storage device to store the file, but there is no inode for managing the information of the file, and thus no more files can be stored.

Second, when the size of the file stored in the file system is large, in the file system using the static bitmap, if the size of the stored file is large, waste of the inode occurs. In other words, if a large amount of files larger than 4KB is stored in the file system, the inode remains, but there is no space to store the files in the storage device, so the files can no longer be stored.

Therefore, since the size of the file stored in the file system cannot be predicted, the static bitmap method based on the file size causes a waste of storage space or a bitmap. In particular, in the case of a mail server system which mainly stores a small amount of data such as e-mail due to the development of the Internet, it causes a waste of storage space, and a management area is wasteful in a multimedia system that stores and services multimedia data such as voice or video. Will cause problems.

Accordingly, the present invention has been made to solve the above-mentioned problems according to the prior art, and an object of the present invention is to allocate a bitmap dynamically without limiting the size of a file generated in a file system, such as a disk. The present invention provides a large file storage system and a dynamic bitmap management method of a large file using the same, which effectively manages a large number of files by increasing the use efficiency of the storage device.

Another object of the present invention is to provide a dynamic bitmap management technique for dynamically allocating bitmaps when an object (inode, directory entry, data block) is generated in a file system, and a method of implementing a large file system using the same. A computer readable recording medium having recorded thereon a program for realizing the above method is provided.

1 is a diagram for describing a layout of a large file storage space in a large file system according to the present invention;

2 is a diagram illustrating a structure of a bitmap area and an allocation area shown in FIG. 1 and management of an allocation area using a bitmap;

3 is a diagram illustrating a bitmap l allocated for an inode and a bitmap m allocated to a data block as a detailed example of the contents shown in FIG. 2;

FIG. 4 is a diagram illustrating a structure of a bitmap stored in the bitmap region illustrated in FIG. 3 and includes a bitmap header and a bitmap.

5 is a flowchart illustrating an operation method for allocating a bitmap in a large file storage system according to the present invention;

6 is a flowchart illustrating an operation for allocating the requested metadata by finding an empty bitmap in FIG. 5;

FIG. 7 is a flowchart illustrating an operation of deleting a corresponding metadata in a large file storage system according to the present invention; FIG.

* Description of the symbols for the main parts of the drawings *

110: super block 120: bitmap area

130: allocated space

According to an aspect of a large-capacity file system according to the present invention for achieving the above object, in the file storage system for implementing a dynamic bitmap structure, the size of the allocation area without distinction according to the type of metadata of the file system And a bitmap structure for dividing the corresponding bitmap according to the bitmap area, and each bitmap of the bitmap area includes a header part for managing bitmap information and a bit area structure indicating whether bitmap management is used or not. However, the bitmaps are classified according to metadata and managed as a bit area by assigning allocation units of the allocation area as a group.

In addition, according to an aspect of the method for managing a dynamic bitmap of a large file in a large file system according to the present invention, if the generation of a new object in the file system occurs, checking the type of the object; If the type of the object is checked, determining whether the requested object type and the bitmap type are the same in the file system by reading the bitmap from the storage device and reading the type value from the header information of the corresponding bitmap; Comparing the used count number and the total number to check whether there is a bitmap not used in the corresponding bitmap if the bitmap types are the same; As a result of the determination, when the number of usage of the bitmap is smaller than the total number, finding an unused bit " 0 " and setting the corresponding bit to " 1 " to indicate that the corresponding allocation area is in use, and increasing the user count of the header. ; Allocating an area of the allocated space corresponding to the bitmap to the corresponding object.

In the checking of the type and in the checking of the bitmap usage counter, if the generated object type and the bitmap type are not the same and the number of use of the bitmap is greater than the total number, the current bitmap area is allocated. Checking whether there is no bitmap in use; As a result of the check, if a bitmap being used exists, a new bitmap is read from the storage device. If no bitmap is used, there is no bitmap for the object to be created in the currently allocated bitmap. Receiving a new bitmap and setting a type to an allocated bitmap of the requested object; And setting the first bit of the newly allocated bitmap to "1" and allocating a corresponding allocated space region to the requested object.

The storage space of the storage device may include a superblock storing information for managing the entire file system, an allocation space for storing an inode, a directory entry, and a data block, and a bitmap area for managing the allocation space. Can be done with

In addition, according to an aspect of the method for deleting a metadata object using a dynamic bitmap structure applied to a file storage system, when a request for deleting an object is received from the file system, a bitmap in which the requested object exists is read from the storage device. Making; Find the corresponding bit in the read bitmap, set the bit value to "0", make it available for the next time, decrease the usage counter in the header information, and check whether the value of the header use counter of the bitmap is "0". Inspecting; As a result of the above check, if the header usage counter is "0", the allocated area of the storage device managed by the current bitmap is not used. Therefore, the header and bit area of the bitmap are set to "0" (free space) so that other objects can be changed. Allocating an area for the data.

Meanwhile, in order to perform a dynamic bitmap management method of a large file in a large file system, a program of instructions that can be executed by a digital processing device is tangibly embodied, and one side of a recording medium that can be read by the digital processing device. According to, if the generation of a new object in the file system occurs, checking the type of the object; If the type of the object is checked, determining whether the requested object type and the bitmap type are the same in the file system by reading the bitmap from the storage device and reading the type value from the header information of the corresponding bitmap; Comparing the usage count and the total number to check whether there is a bitmap not used in the corresponding bitmap if the bitmap types are the same; As a result of the determination, if the number of use counts of the bitmap is smaller than the total number, finding unused bit "0", setting the corresponding bit to "1" to indicate that the corresponding allocation area is in use, and increasing the number of user counts in the header. ; Allocating an area of the allocation space corresponding to the bitmap to the corresponding object.

Hereinafter, a preferred embodiment of a method for managing a dynamic bitmap of a large file in a large file system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a layout of a large file storage space in a large file system according to the present invention, and illustrates a structure of a storage space for storing a file system.

As shown in FIG. 1, the storage space includes a superblock 110 for storing information for managing the entire file system, an allocation space 130 for storing inodes, directory entries, and data blocks, and an allocation. It is composed of a bitmap area 120 for managing the space 130. Here, the size of the bitmap can be obtained by using Equations 1 and 2 below.

BC = SUB-BH

Here, BC denotes the number of allocation units of the spatial region indicated by the unit bitmap, SUB denotes the size of the unit bitmap, and BH denotes the size of the bitmap head.

BS = TAS / SUA / BC

Here, BS is the size of the bitmap, TAS is the size of the total allocated space, and SUA is the size of the data block or extent.

FIG. 2 is a diagram illustrating a structure of a bitmap area and an allocation area shown in FIG. 1 and management of an allocation area using a bitmap, and illustrates a relationship between a bitmap and an allocation space.

As shown in FIG. 2, one unit bitmap 121 and 122 manages the unit allocation areas 131 and 132 in the n allocation spaces 130. That is, the 0 th bitmap 121 manages the first area 131 of the allocation space 130 and the last m bitmap manages the m th 132 in the allocation space.

FIG. 3 is an exemplary diagram illustrating FIG. 2 in detail, and shows an example in which an arbitrary bitmap is allocated for an inode 121A and a data block 121B in the bitmap region 120.

As shown in FIG. 3, the bitmap l allocated for the inode manages the corresponding region 131-1 of the allocation region 130 as a space for storing the inode. In the example of FIG. 3, the allocation unit of the allocation area is managed by ten units. In the inode bitmap 121A, seven out of ten are in use (131-1B) and three (131-1B) remain. Whether the allocation space 130 is used or not is indicated by displaying "0" and "1" in the bit area in the bitmap. In the same way, the allocation space 131-2 managed by the data block bitmap 121B is used as a space for storing the data block. In the present embodiment, three data blocks 131-2B are allocated and used. Shows that there is.

The structure of each bitmap is shown in FIG. Each bitmap is divided into a header 121-1 for managing the corresponding bitmap 121 and a bit area 121-2 indicating whether the allocated space is used.

The information stored in the header for managing the bitmap maintains information such as the bitmap type, the total number of allocation areas maintained by the bitmap, and the number of areas already allocated. The bitmap type identifies the type of the corresponding bitmap and is used to distinguish whether the bitmap is an inode, a directory entry, or a data block. If the bit value is "1" (121-2A), it means that the corresponding area in the allocation space has already been allocated. If the bit value is "0" (121-2B), it means that the corresponding area is not allocated.

In FIG. 3, the i-th bitmap is a bitmap for the inode, and the total number of allocated regions managed by the bitmap (n value in FIG. 2) is 60, of which 41 are in use.

5 is a flowchart illustrating an embodiment of creating an object in a large file storage system according to the present invention.

Referring to FIG. 5, first, when a generation of a new object in the file system occurs, the type of the object is checked (S510). Here, the type of object may be an inode, a directory entry, a data block, or the like.

Subsequently, when the checking of the generated object type is completed, an allocation operation process for the corresponding object is performed (S520). That is, it allocates an empty area for the object in the bitmap.

Here, step S520, that is, with reference to Figure 6 attached to the allocation operation process for the object will be described in more detail.

FIG. 6 is a flowchart illustrating an operation of the allocation operation illustrated in FIG. 5. First, a bitmap is read from a storage device (S521), and a type value is read from a header information of the corresponding bitmap, which is requested by the file system. It is determined whether the object type and the bitmap type are the same (S522).

As a result of the determination in step S522, if the bitmap types are the same, the usage count and the total number are compared to check whether there is a bitmap not used in the corresponding bitmap (S523). That is, when the usage count and the total number are the same, it means that all the bits are used.

As a result of the determination in step S523, when the number of use of the bitmap is smaller than the total number, the unused bit “0” is found and the corresponding bit is set to “1” to indicate that the corresponding allocation area is in use, and the number of use count of the header is determined. Increase (S524).

Subsequently, an area of the allocated space corresponding to the bitmap is allocated to the corresponding object (S525).

If the step S522 of checking the type and the step S523 of checking the usage counter of the bitmap are not satisfied, that is, the generated object type and the bitmap type are not the same and the number of use of the bitmap is greater than the total number. If it is large, a new bitmap must be read from the storage device. In order to proceed with this process, it is necessary to check whether there is no bitmap currently allocated to the bitmap area (S526).

As a result of the determination in step S526, if a bitmap being used exists, a new bitmap is read from the storage device (S522), but if there is no bitmap being used, the object to be created in the currently allocated bitmap Since no bitmap exists for, a new bitmap must be allocated. Therefore, the bitmap area is searched for and an unused bitmap is selected to set the type to the requested bitmap (S527).

Subsequently, the first bit of the newly allocated bitmap is set to "1", and the corresponding allocated space area is allocated to the requested object (S528).

7 is a flowchart illustrating an operation of deleting a corresponding metadata in a large file storage system according to the present invention.

As shown in FIG. 7, when a deletion request for an object is received in a file system, a bitmap in which a requested object exists is read from a storage device (S610).

Find the corresponding bit in the bitmap read in step S610, set the bit value to 0 to enable the next use, and decrease the usage counter in the header information (S620). 0 "application is checked (S630).

As a result of the determination in step S630, if the header usage counter is "0", since the allocation area of the storage device managed by the current bitmap is not used, the header and bit area of the bitmap are set to "0", The value of the bitmap is set to "0" so that the bitmap can be allocated to an area for another object (S640).

As described above, the method for managing a dynamic bitmap of a large file according to the present invention may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.). have.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill.

As described above, the present invention effectively allocates a bitmap to manage a file system, thereby reducing the waste of storage space generated according to the size of the file, thereby ensuring maximum utilization rate, thereby effectively recovering a dynamic bitmap of a large file. It can be managed.

In particular, using the present invention in a storage system in which a small amount of files exist, such as an e-mail server on the Internet, the problem of not being able to save files due to lack of inode and directory entry despite the storage space remaining is solved. Can be.

On the contrary, if the present invention is used in a storage system that stores a large file such as multimedia data, at least an inode and a directory entry can be allocated to maximize the area of the data block in the allocated space, thereby reducing waste.

In addition, the present invention can be effectively used for mass storage devices, such as a storage area network (SAN) or a network attached storage (NAS), which has a large area of metadata due to an increase in capacity in the future, so that the storage device at the time of storing large files Can be used efficiently.

Claims (8)

In a file storage system for implementing a dynamic bitmap structure, Includes a structure that classifies and allocates the bitmap according to the size of the allocation area without distinguishing the type of metadata of the file system, Each bitmap of the bitmap region includes a header portion for managing bitmap information and a structure of a bit region indicating whether bitmaps are managed or not. The bitmap is classified according to metadata, and the bitmap is managed as a bit area by using allocation units of an allocation area as a group. In the dynamic bitmap management method of a large file in a large file system, Checking the type of the object when a new object is generated in the file system; If the type of the object is checked, determining whether the requested object type and the bitmap type are the same in the file system by reading the bitmap from the storage device and reading the type value from the header information of the corresponding bitmap; Comparing the usage count and the total number to check whether there is a bitmap not used in the corresponding bitmap if the bitmap types are the same; As a result of the determination, when the number of usage of the bitmap is smaller than the total number, finding an unused bit " 0 " and setting the corresponding bit to " 1 " to indicate that the corresponding allocation area is in use, and increasing the user count of the header. ; And allocating an area of an allocated space corresponding to the bitmap to a corresponding object. The method of claim 2, In the checking of the type and in the checking of the bitmap usage counter, if the generated object type and the bitmap type are not the same and the number of use of the bitmap is greater than the total number, the current bitmap area is allocated. Checking whether there is no bitmap in use; As a result of the check, if a bitmap being used exists, a new bitmap is read from the storage device. If no bitmap is used, there is no bitmap for the object to be created in the currently allocated bitmap. Receiving a new bitmap and setting a type to an allocated bitmap of the requested object; And setting the first bit of the newly allocated bitmap to "1" and allocating a corresponding allocated space area to the requested object. The method of claim 2, The storage space of the storage device, A superblock that stores information for managing the entire file system, Allocation space for storing inodes, directory entries, and data blocks, Dynamic bitmap management method of a large file in a large file system consisting of a bitmap area for managing the allocated space. The method of claim 4, wherein The size of the bitmap in the bitmap area is dynamic bitmap management method of a large file in a large file system using Equations 1 and 2 below. [Equation 1] BC = SUB-BH Here, BC denotes the number of allocation units of the spatial region indicated by the unit bitmap, SUB denotes the size of the unit bitmap, and BH denotes the size of the bitmap head. [Equation 2] BS = TAS / SUA / BC Here, BS is the size of the bitmap, TAS is the size of the total allocated space, and SUA is the size of the data block or extent. The method of claim 2, The type of the object, dynamic bitmap management method of a large file in a large file system including at least one type of inode, directory entries, data blocks. In the metadata object deletion method using a dynamic bitmap structure applied to a file storage system, Reading from the storage device a bitmap in which the requested object exists when the deletion request for the object is received from the file system; Find the corresponding bit in the read bitmap, set the bit value to "0", make it available for the next time, decrease the usage counter in the header information, and check whether the value of the header use counter of the bitmap is "0". Inspecting; As a result of the check, if the header usage counter is "0", the allocation area of the storage device managed by the current bitmap is not used. Therefore, the header and bit area of the bitmap are set to "0" to be allocated to the area for other objects. A method of deleting metadata objects using a dynamic bitmap structure applied to a file storage system, the method comprising: In order to perform a dynamic bitmap management method of a large file in a large file system, a program of instructions that can be executed by a digital processing device is tangibly implemented, and in a recording medium that can be read by a digital processing device, Checking the type of the object when a new object is generated in the file system; If the type of the object is checked, determining whether the object type and the bitmap type requested by the file system are the same by reading the bitmap from the storage device and reading the type value from the header information of the corresponding bitmap read from the storage device; Comparing the usage count and the total number to check whether there is a bitmap not used in the corresponding bitmap if the bitmap types are the same; As a result of the determination, when the number of usage of the bitmap is smaller than the total number, finding an unused bit " 0 " and setting the corresponding bit to " 1 " to indicate that the corresponding allocation area is in use, and increasing the user count of the header. ; And allocating an area of the allocated space corresponding to the bitmap to the corresponding object.