WO2009110377A1

WO2009110377A1 - Metaserver and file management system

Info

Publication number: WO2009110377A1
Application number: PCT/JP2009/053655
Authority: WO
Inventors: 純一大和; 欽一杉本; 純明榮; 真澄一圓
Original assignee: 日本電気株式会社
Priority date: 2008-03-05
Filing date: 2009-02-27
Publication date: 2009-09-11
Also published as: JPWO2009110377A1; JP5257444B2

Abstract

A metaserver manages mapping information which manages allocation of data constituting a file to a storage device. A metaserver comprises a unit of acquiring a file open request, a unit of acquiring mapping information, and a unit of transmitting mapping information. When receiving a file open request from a host, the unit of acquiring mapping information acquires the mapping information relating to a file to open from a unit of storing mapping information. The unit of transmitting mapping information returns the mapping information acquired by the unit of acquiring mapping information to the host which transmitted the file open request.

Description

Meta server and file management system

The present invention relates to a meta server, and more particularly, to a meta server that manages mapping information that manages allocation of data making up a file to a storage device. The present invention relates to a file management system, a file management method, and a program that perform file management in a file system using such a meta server.

In the file system, there is a file system in which the configuration of data blocks or objects that make up a file is managed by using a device (metaserver) that performs block allocation management without managing the configuration of the file or host (for example, Patent Document 1). FIG. 13 shows a file system of such a configuration. The meta server 103 stores, for each data block constituting a file, mapping information indicating which area (block) in the storage apparatus the data block is mapped to.

FIG. 14 shows a sequence at the time of access in the meta server. At the time of access such as read / write, the host 101 inquires the meta server 103 about mapping information of data blocks in the file to be accessed (step S101). The meta server 103 returns the mapping information of the corresponding data block to the host 101 (step S102). The host 101 accesses the storage apparatus 102 using the acquired mapping information (step S103).

Literature list:
Information Processing Society of Japan 57th (late 1998) national convention performances collection (1) "Summary of parallel file system PF3" Junichi Yamato, Hiroyuki Otani, Yuichi Tate, Hisayuki Aoki NEC C & C Media Research Institute p99, p100, and "File Management Method in Parallel File System PF3" Hiroyuki Otani, Junichi Yamato, Yuichi Tetsu, Hisayuki Aoki NEC C & C Media Research Laboratories p101, p102, Date of issue: October 5, 1998

In the file system using the above meta server, it is necessary to inquire the meta server 103 about the mapping information each time the host 101 accesses the storage apparatus 102. For this reason, the response time of file access becomes long. A method is also conceivable in which the host 101 caches the mapping information acquired in step S102 and shortens the response time. However, even in this case, the response time can not be shortened unless the same data block is repeatedly accessed.

An object of the present invention is to provide a file management system, a file management method, and a program that can be used in a file system having an allocation management device (meta server) and can reduce response time at the time of access.

The present invention is a file management method used in a file system having a meta server for managing mapping information for managing allocation of data constituting a file to a storage device, wherein the meta server receives a file open request from a host, A file management method comprising: acquiring mapping information of a file to be opened from a mapping information storage unit storing mapping information; and transmitting the acquired mapping information to the host. Do.

The present invention is also a meta server that manages mapping information that manages allocation of data making up a file to a storage device, and from the mapping information storage unit that stores the mapping information when there is a file open request from the host, A meta server comprising: a mapping information acquisition unit for acquiring mapping information of a file to be opened; and a mapping information transmission unit for transmitting the mapping information acquired by the mapping information acquisition unit to the host.

The present invention is further a meta server for managing mapping information for managing allocation of data constituting a file to a storage device, and from the mapping information storage unit for storing the mapping information when there is a file open request from the host. A meta server having a mapping information acquisition unit for acquiring mapping information of a file to be opened, and a mapping information transmission unit for transmitting the mapping information acquired by the mapping information acquisition unit to the host, and transmitted from the meta server when the file is opened And a host having a mapping information cache for registering the mapping information in the cache.

The present invention further relates to a program for a file system having a meta server that manages mapping information for managing allocation of data making up a file to a storage device, and when the meta server receives a file open request from a host, A program is provided, which executes processing of acquiring mapping information of a file to be opened from a mapping information storage unit storing mapping information, and processing of transmitting the acquired mapping information to the host.

The file management system, file management method, meta server, and program of the present invention can shorten the response time when the host accesses data.

The above and other objects, features and advantages of the present invention will become apparent from the following description made with reference to the drawings.

FIG. 1 is a block diagram showing a file management system according to a first embodiment of the present invention. (A)-(d) is a diagram which shows the example of data of mapping information. (A)-(d) is a diagram which shows another example of data of mapping information. 6 is a flowchart showing the processing procedure of the host at the time of file open. The flowchart which shows the processing procedure of the meta server at the time of file open. The block diagram which illustrates the rule used in the case of mapping information acquisition range determination. The flowchart which shows the processing procedure of mapping information acquisition. (A)-(d) is a diagram which shows the example of data of mapping information cache. (A)-(d) is a diagram which shows another example of data of mapping information cache. 6 is a flowchart showing the processing procedure of the host at the time of file access. The flowchart which shows the processing procedure of the meta server at the time of file access. FIG. 7 is a block diagram showing a file management system according to a second embodiment of the present invention. A block diagram showing a file system using a meta server. FIG. 14 is a sequence diagram showing the flow of processing at the time of file access in the file system shown in FIG. 13;

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a file management system according to a first embodiment of the present invention. The file management system has a host 10, a storage device 20, and a meta server 30. The host 10 is a computer on which a user program operates. The storage device 20 is a storage device that stores data. The meta server 30 is a computer that manages mapping information that is a correspondence between data blocks that make up a file and data blocks in the storage apparatus 20. The functions of each unit in the host 10 and the meta server 30 can be realized by executing a predetermined program on a computer. Although only one host 10 is illustrated in FIG. 1, a plurality of hosts 10 may be provided.

The host 10 has a file access unit 11. On the host 10, a user program is operating. The host 10 requests the meta server 30 to open the file prior to access (read / write) to the file. After the file is opened, the user program accesses the data of the target file in the storage device 20 based on the mapping information managed by the meta server 30 via the file access unit 11.

The file access unit 11 has a mapping information cache 12 that caches the mapping information acquired from the meta server 30. The mapping information cache 12 is a storage device that holds mapping information. When the mapping information corresponding to the data block to be accessed exists in the mapping information cache 12, the file access unit 11 accesses the data block using the mapping information. When the mapping information cache 12 does not have mapping information corresponding to a data block to be accessed, the file access unit 11 acquires mapping information on the data block to be accessed from the meta server 30.

The meta server 30 includes a file open request reception unit 31, a mapping information acquisition request reception unit 32, an open-time mapping information return range determination unit 33, a mapping information acquisition unit 34, a response return unit 35, and a mapping information storage unit 36. The mapping information storage unit 36 stores mapping information in the storage device. The mapping information acquisition request receiving unit 32 receives a mapping information acquisition request from the host. When receiving the mapping information acquisition request, the mapping information acquisition request accepting unit 32 instructs the mapping information acquisition unit 34 to acquire the mapping information corresponding to the file and data block designated by the request. The mapping information acquisition unit 34 acquires, from the mapping information storage unit 36, mapping information indicating which area in the storage apparatus 20 the data block to be accessed is stored in, and passes it to the response return unit 35. The response return unit 35 returns, to the host 10, a response to the mapping information acquisition including the mapping information acquired by the mapping information acquisition unit 34.

The file open request receiving unit 31 receives a file open request from the host 10. When the file open request reception unit 31 receives the file open request, the file open request reception unit 31 instructs the open time mapping information return range determination unit 33 to determine the range of mapping information to be returned to the host 10 together with the file open request. When receiving the instruction for range determination, the open-time mapping information return range determination unit 33 determines the range of mapping information to be returned to the host 10 together with the response to the file open. The file open mapping information return range determination unit 33 determines, for example, the mapping information corresponding to the range of the data area expected to be accessed after the file open as the range of mapping information to be returned. After the determination of the range, the open-time mapping information return range determination unit 33 instructs the mapping information acquisition unit 34 to acquire the mapping information of the determined range. The mapping information acquisition unit 34 acquires the mapping information of the instructed range from the mapping information storage unit 36 and passes it to the response return unit 35. The response return unit 35 returns the response to the file open request including the mapping information acquired by the mapping information acquisition unit 34 to the host 10.

The storage device 20 is a magnetic disk for storing data, a magneto-optical disk, an optical disk, a non-volatile memory, and their array device. There may be a plurality of storage devices 20. If there are multiple storage devices, the mapping information includes the identifier of the storage device storing the data block. In this case, the host 10 refers to the mapping information and accesses the corresponding storage device 20 based on the storage device identifier. The storage device 20 may be a device such as an OSD (Object-Based Storage Device). In the present embodiment, the storage device 20 is mainly described as a block access device, but it is also applicable to the OSD by treating a data block as an object.

The meta server 30 manages the mapping information as a table consisting of records of the mapping information. FIGS. 2A to 2D show examples of records stored in the mapping information table. The record of the mapping information is composed of area information in the file and information of the storage device in which the area is actually stored. FIGS. 2A and 2B show an example in which the storage device is a block device. The area information in the file is composed of a set of the start address and end address of the area in the file, or a set of the start address and the area size. The area information in the storage device is composed of a set of the start address and end address of the area in the storage device, or a set of the start address and the area size. FIGS. 2C and 2D are examples of the case where the storage device is an OSD. In the case of OSD, the ID of the object is the information of the storage device stored in the implementation.

FIGS. 3A to 3D show another example of the records stored in the mapping information table. These are examples in the case where a file is divided and stored in a plurality of storage devices. FIGS. 3A and 3B show an example in which the storage device is a block device. The difference from FIGS. 2A and 2B is that information (storage device ID) for specifying a storage device that stores the corresponding area is added. FIGS. 3C and 3D show an example of the case where the storage device is an OSD. The difference from FIGS. 2C and 2D is that a storage device ID is added. As the storage device ID, the storage device ID, SCSI ID, Fiber Channel WWN (world wide name), IP address, MAC address, URL, etc. can be used.

FIG. 4 shows the processing procedure of the host 10 when the file is open. When the file is opened, a path name of the file is designated to the host 10 by an operator or the like. The host 10 first acquires file identification information for acquiring mapping information from the file path name (step A1). Step A1 is a process performed by another server or a directory server, and is a process (path name resolution process) for acquiring file identification information such as a file handle for acquiring file mapping information. The process of path name resolution is similar to the process of path name resolution by lookup in NFS, and the details will be omitted.

Next, the host 10 requests the meta server 30 to open the file by designating the file identifier (step A2), and waits until a response is returned (step A3). When the meta server 30 receives the open request, it performs processing to open the file. FIG. 5 shows the procedure of the open process in the meta server 30. The meta server 30 receives the open request from the file open request receiving unit 31. The file open request receiving unit 31 searches for information of a file corresponding to the file identifier designated by the open request (step B1). The meta server 30 determines whether or not the information of the corresponding file is found as a result of the search, that is, whether or not the mapping information for the data blocks constituting the corresponding file exists in the mapping information storage unit 36 ( Step B2).

The meta server 30 manages the correspondence between the file and the data block constituting the file, and the correspondence between each data block and the record of the mapping information. The file open request receiving unit 31 can determine whether the mapping information storage unit 36 has mapping information on data blocks constituting the corresponding file by referring to the correspondence relationship. When the file open request receiving unit 31 determines that the mapping information exists, the file open request reception unit 31 sets the corresponding file as a file to be subjected to the open process.

If the file open request receiving unit 31 determines that there is no mapping information in step B2, it determines whether file creation is designated in the file open request (step B3). If the file open request receiving unit 31 determines that the file creation is not specified in step B3, the file open request reception unit 31 instructs the response return unit 35 to return an error response to the effect that open failed. The response return unit 35 returns an error response to the host 10 according to this instruction (step B5), and ends the process. If the file open request receiving unit 31 determines that file creation is designated in step B3, it creates and initializes a new area for the file (step B4). The file open request reception unit 31 sets the file created in step B4 as a file to be subjected to the open process.

The file open request receiving unit 31 changes the status of the file to be opened, that is, the file searched in step B1 or the file created in step B4 to the open state (step B6). Thereafter, the open-time mapping information return range determination unit 33 is instructed to determine the range of the mapping information to be included in the response to be returned to the host 10. The open time mapping information return range determination unit 33 that has received this instruction determines the range of the mapping information (step B7). The open time mapping information return range determination unit 33 notifies the mapping information acquisition unit 34 of the range determined in step B7, and requests acquisition of the mapping information of the range.

The range determination by the open time mapping information return range determining unit 33 will be described. The open time mapping information return range determination unit 33 can determine the mapping information corresponding to the data area of a predetermined size defined in advance from the top of the file to be opened as the range of the mapping information included in the response. . Also, the open-time mapping information return range determination unit 33 can determine the mapping information corresponding to the data area of a predetermined size counting from the end of the file as the range of the mapping information to be included in the response. The mapping information return range determination unit 33 for open includes, in the response, mapping information corresponding to both a data area of a predetermined size from the beginning of the file and a data area of a predetermined size counting from the end of the file. It can also be determined as a range.

The open-time mapping information return range determination unit 33 determines the range of mapping information to be returned using a rule that specifies mapping information corresponding to which data area in the file as mapping information included in the response. You can also. The rules may be common to each file, or may be prepared for each file. When preparing for each file, file information and rules may be set and applied only when the file information matches. In this case, rules can be set in file units. In addition, an attribute indicating the file type may be added to the meta information of the file, and the file type and the rule may be set as a set, and a rule having the same type may be applied. In this case, appropriate rules can be set according to file types such as database table files, database index files, moving image files, and encoding methods for moving image files.

An example of a rule is shown in FIG. The rules are created in advance by a system administrator or the like. Alternatively, the user may arbitrarily create it. In FIG. 6, in the file information entry, information specifying a file to which this rule is applied is stored. File names, file extensions, etc. can be used as the file information. In this example, n data areas are designated from area 1 to area n. Arbitrary areas are set in areas 1 to n. These data areas do not have to be continuous data areas. Also, the area may be one. The area designated by the rule is preferably a data area expected to be accessed after the file open in accordance with the data characteristic of the file. When a plurality of data areas are designated as in the rule shown in FIG. 6, the open-time mapping information return range determination unit 33 sets a range group consisting of a pair of the start address and the end address of each data area as mapping information. Pass to the acquisition unit 34.

In FIG. 6, the area is specified by a combination of the start address and the end address, but the area may be specified by a combination of the start address and the size of the area. Also, the area may be designated by a combination of the end address and the area size. In the rule, the designation of the area by the combination of the start address and the area size and the designation of the area by the combination of the end address and the area size may be mixed. In this case, a flag indicating whether the area is specified from the end address or the area specified from the start address may be provided in the specification of each area. By specifying the area by the address of the head or end and the area size, it is possible to specify an area within a predetermined range from the head or end in the rule for files of various lengths.

Returning to FIG. 5, the mapping information acquisition unit 34 acquires mapping information corresponding to the area specified by the open mapping information return range determination unit 33 (step B8). If the range determined by the file open time mapping information return range determination unit 33 is a range spanning a plurality of data blocks, the mapping information acquisition unit 34 acquires records (FIG. 2) of a plurality of mapping information. The mapping information acquisition unit 34 passes the acquired mapping information to the response return unit 35. The response return unit 35 returns the success response to the file open request including the mapping information acquired in step B8 to the host 10 (step B9).

FIG. 7 shows the processing procedure of the mapping information acquisition unit 34. The mapping information acquisition unit 34 receives the target file and the data range in the target file, and acquires the mapping information. The mapping information acquisition unit 34 selects a data range to be acquired (step C1). In step C1, when a plurality of areas are passed to the mapping information acquisition unit 34, one area is selected from the area group. The mapping information acquisition unit 34 sets the head address of the area selected in step C1 as a search target address (step C2).

The mapping information acquisition unit 34 searches for a mapping information entry that includes the search target address set in step C2 in the range of the area information from the mapping information of the specified file (step C3). The mapping information acquisition unit 34 creates mapping information to be returned to the host 10 based on the mapping information entry searched in step C3 (step C4). In step C4, the mapping information acquisition unit 34 acquires the contents of the mapping information entry searched in step C3 from the mapping information storage unit 36, and adds the acquired contents to the mapping information to be returned to the host.

The mapping information acquisition unit 34 determines whether the area information of the mapping information entry includes the end address of the data range selected in step C1 (step C5). If the end address is not included in the data area range of the mapping information entry, the next address of the end address of the mapping information entry searched in step C3 is searched for in order to obtain the mapping information of the subsequent data range. And (step C6), it returns to step C3.

If the mapping information acquisition unit 34 determines in step C5 that the end address of the data range is included in the data area range of the mapping information entry, that is, if the mapping information for all of the data range selected in step C1 is obtained, End acquisition of mapping information of the data range. The mapping information acquisition unit 34 determines whether there is a data range for which the mapping information has not been acquired yet (step C7). If it exists, the mapping information acquisition unit 34 selects one from the unprocessed data range (step C8), returns to step C2, and acquires the mapping information of the selected data range.

If the mapping information acquisition unit 34 determines that there is no unprocessed data range in step C7, it passes the created mapping information to the response return unit 35 (step C9), and ends the process. The mapping information acquired by the mapping information acquiring unit 34 is transmitted by the response returning unit 35 to the host 10 in step B9 of FIG.

If there is no entry of the corresponding mapping information at step C3, the area is not allocated to the storage device 20 yet. In this case, if the mapping information acquisition unit 34 acquires mapping information at the time of file open, it notifies that it is not allocated, shifts the search address later, and exists in the end of the area. Get mapping information.

Returning to FIG. 4, upon receiving the response to the open request, the host 10 registers the mapping information included in the response in the mapping information cache 12 in association with the file information (step A4). Note that, as in the case of NFSv2, when there is no explicit open processing only for pathname resolution, steps A2 and A3 are not necessary. In that case, since the mapping information is returned in the path name resolution process of step A1, the mapping information returned at that time may be registered in the mapping information cache 12 in step A4.

FIGS. 8A to 8D show examples of the records of the mapping information recorded in the mapping information cache 12. FIG. Further, FIGS. 9A to 9D show another example of the record of the mapping information recorded in the mapping information cache 12. The record of the mapping information recorded in the mapping information cache 12 is for identifying the file with the mapping information (FIGS. 2A to 2D or 3A to 3D) in the meta server 30. And file information of The file information includes a combination of information specifying a file system and an inode number or vnode number of the file system, a combination of information specifying an NFS server in NFS (Network File System) and a file handle, or a file The path name etc. of can be used.

Subsequently, the host 10 performs an open process of the storage device 20 (step A5). The open process in the storage device of step A5 is a process of acquiring information for accessing the storage device. This open process is the same process as the LOGIN process in iSCSI, and the details will be omitted. Step A5 may be omitted if the storage apparatus 20 does not require the open process.

FIG. 10 shows a processing procedure when the host 10 accesses (reads / writes) a file. The host 10 instructs the file access unit 11 to specify the file to be accessed and the area to be accessed, and instructs the file access. The area to be accessed is a range of data blocks, and is specified by a set of a head address and a termination address or a set of a head address and a size.

When access to a file from a user program or the like occurs, the file access unit 11 searches the mapping information cache 12 (step D1), and for the file to be accessed, does mapping information corresponding to the data area to be accessed exist? It is judged whether or not it is (step D2). When mapping information corresponding to the entire range of the data area to be accessed exists in the mapping information cache 12, necessary mapping information is acquired from the mapping information cache 12, and the process shifts to access to the storage device 20.

If the file access unit 11 determines in step D2 that there is no mapping information for the entire range to be accessed or no mapping information for a part of the areas for the file to be accessed, transmission of the mapping information for the nonexistent area is performed. , Requests the meta server 30 (step D3), and waits for a response from the meta server 30 (step D4).

The host 10 notifies the meta server 30 of "file information" for which the mapping information is to be acquired and "one or more pieces of information indicating the data range for acquiring the mapping information" to request transmission of the mapping information. File information is information for identifying a file. For file information, use a combination of file system identification information and file system inode number or vnode number, combination of NFS server identification information and file handle, file path name, etc. it can. The data range for acquiring the mapping information is specified by a set of the start address of the area in the file and the end address of the area in the file, or a set of the start address of the area in the file and the size of the area.

FIG. 11 shows the processing procedure of the meta server 30 when there is a mapping information acquisition request from the host 10. The meta server 30 receives the acquisition request of the mapping information transmitted from the host 10 by the mapping information acquisition request accepting unit 32. The mapping information acquisition request receiving unit 32 instructs the mapping information acquisition unit 34 to acquire mapping information, with the mapping information of the specified file as the search target and the specified data area as the search range (step E1). The mapping information acquisition unit 34 acquires the mapping information according to the instruction from the mapping information acquisition request receiving unit 32 (step E2). Acquisition of mapping information by the mapping information acquisition unit 34 at this time is the same as the procedure shown in FIG.

If there is no entry of the corresponding mapping information in step C3 of FIG. 7, the area is not allocated to the storage device 20 yet. In this case, if it is the mapping information acquisition accompanying read, it notifies that it is not allocated as well as the processing at the time of opening, shifts the search address later, and the allocated area exists until the end of the area. Get mapping information of In the case of write, data blocks or objects in the storage device are allocated. This allocation process is similar to the allocation of data blocks in the file system. In the case of the OSD, an unused object ID is assigned. When the storage device 20 is configured of a plurality of storage devices, before assigning an entry in the storage device by write, the storage device to which the area is to be assigned is also determined.

In step E2, the mapping information acquisition unit 34 acquires, from the mapping information storage unit 36, the mapping information corresponding to the data area to be accessed of the access target file requested from the host 10. The response return unit 35 receives the mapping information from the mapping information acquisition unit 34, and returns a response including the received mapping information to the host 10 (step E3).

Returning to FIG. 10, when receiving the mapping information from the meta server 30, the file access unit 11 registers the received mapping information in the mapping information cache 12 in association with the file information of the corresponding file (step D5). The cache registration of the mapping information is the same as the operation of the data cache operating on the host 10 and the operation of the DNLC (Directory Name Lookup Cache) of NFS, except that the information to be registered is the mapping information. The file access unit 11 accesses the storage device 20 using the mapping information searched in step D1 or the mapping information acquired from the meta server 30 in step D3 (step D6), and ends the process.

The processing of read / write access in the storage device 20 is the same as the processing of read / write in a disk device, NAS (Network Attached Storage), OSD, disk array device or the like. In FIG. 10, after the mapping information is cached in step D5, the storage device 20 is accessed in step D6, but either of these processes may be preceded. Alternatively, access to the storage device 20 and cache registration of mapping information may be performed in parallel.

In the present embodiment, the meta server 30 returns mapping information of the file to be opened to the host 10 at the time of the file open request before the host 10 actually reads / writes to the file. The host 10 registers the mapping information transmitted from the meta server 30 at the time of file open in the mapping information cache 12. When the host 10 accesses the file after the file open, if the mapping information corresponding to the data area to be accessed exists in the mapping information cache 12, the host 10 can access the data area using the mapping information. . That is, the host 10 can access the file again without requesting the meta server 30 to acquire the mapping information by caching the mapping information in advance after the file open. By transmitting mapping information of a data area expected to be accessed after the file open from the meta server 30 to the host 10 at the time of the file open, the host 10 can immediately access the data area, Access response time can be shortened.

The file access unit 11 also registers the mapping information acquired from the meta server 30 at the time of file access in the mapping information cache 12 (step D5 in FIG. 10). By using this mapping information cache, it is possible to shorten the access response time when accessing the same data area of the same file again. However, with only the mapping information cache at the time of file access, it is not possible to shorten the access response time for a file that has not yet been accessed just by opening the file. In the present embodiment, when the file is opened, mapping information that is not originally required by the file open is transmitted from the meta server 30 to the host 10, and this is registered in the mapping information cache 12 to respond to access after the file open. Time can be shortened.

The meta server 30 in the file management system of the above embodiment has a file open request reception unit 31, a mapping information acquisition unit 34, and a mapping information transmission unit (response return unit) 35 as a basic configuration of the meta server of the present invention. When receiving a file open request from the host 10, the mapping information acquisition unit 34 acquires mapping information of the file to be opened from the mapping information storage unit 36 that stores the mapping information. The mapping information transmission unit (response return unit) 35 transmits the mapping information acquired by the mapping information acquisition unit 34 to the host 10 that has transmitted the file open request via the communication line. The mapping information storage unit 36 may be connected to the outside of the meta server 30 via the communication line 40 with the meta server 30.

In the file management system of the above embodiment, the meta server used in the system, the file management method, and the program, the host 10 can acquire the mapping information from the meta server 30 when the file open request is sent, Can reduce the access time required to access files.

In the above embodiment, a configuration for caching mapping information is adopted. Since the mapping information has a smaller capacity than the data itself, there is an advantage that the storage device 20 of the host 10 can use a small amount of cache capacity (storage capacity). In addition, the amount of communication in communication related to acquisition of mapping information can be reduced. As the form of transmitting the mapping information from the meta server 30 to the host 10 at the time of the open, the form of transmitting the mapping information separately from the response to the open request can also be considered. However, in this case, the number of communications between the host 10 and the meta server 30 will increase, so from the viewpoint of reducing the number of communications, it is advantageous to send the response to the open request including the mapping information. is there.

As an operation of the mapping information cache 12, an operation of invalidating the cache (deleting of the mapping information) can be considered at fixed time intervals. In such a case, it is preferable that the range of the mapping information transmitted from the meta server 30 to the host 10 at the time of file open be a range corresponding to the data area which may be accessed within the invalidated time. The data area that may be accessed within the invalidated time is determined by the system administrator or the like from the access history, file transfer speed, and the like. By setting the determined data range as a rule to be referred to when the open-time mapping information return range determining unit 33 determines the range of the mapping information, acquisition of invalidated mapping information can be avoided.

FIG. 12 shows a file management system according to the second embodiment of this invention. The configuration of this embodiment is a configuration in which a mapping information acquisition logging unit 37 and a rule determination unit 38 are added to the meta server 30 to the configuration of the first embodiment (FIG. 1). The mapping information acquisition logging unit 37 collects the history of mapping information acquisition requests transmitted from the host 10 arriving at the meta server 30. The rule determination unit 38 refers to the history collected by the mapping information acquisition logging unit 37 to check the access to the file after the file open, and the mapping information return range determination unit 33 at open time returns the mapping information to be returned at file open time. Create a rule to use in determining the range.

The rule determination unit 38 examines the data area accessed by the host 10 from the history of the mapping information acquisition request transmitted by the host after the file open. For example, when the host 10 transmits the mapping information acquisition request five times sequentially from the file top side after the file open, the rule determination unit 38 sends a data range for five data blocks from the file top to the host 10 at open time. Create a rule that is the data range of the mapping information to be returned. The open time mapping information return range determination unit 33 determines the range of the mapping information to be returned to the host 10 when the file is open, with reference to the created rule. By doing this, it is possible to transmit, to the host 10 at the time of the file open, the mapping information of the data area that is likely to be accessed by the host 10 after the file open. The other effects are the same as in the first embodiment.

Although the invention has been particularly shown and described with reference to the exemplary embodiments, the invention is not limited to the embodiments and the variations thereof. As will be apparent to those skilled in the art, the present invention is capable of various modifications without departing from the spirit and scope of the present invention as defined in the appended claims.

This application is based on and claims the priority of Japanese Patent Application No. 2008-055095, filed March 5, 2008, the entire content of the disclosure of which is incorporated herein by reference. join.

Claims

A file management method for use in a file system having a meta server for managing mapping information for managing allocation of data constituting a file to a storage device, comprising:
Obtaining the mapping information of the file to be opened from the mapping information storage unit storing the mapping information when the meta server receives the file open request from the host;
A file management method, comprising: the meta server transmitting the acquired mapping information to the host.
The file management method according to claim 1, further comprising the step of the host registering the mapping information transmitted from the meta server at the time of file open in a mapping information cache.
3. The file management method according to claim 1, wherein, in the step of transmitting the mapping information to the host, the meta server transmits the mapping information included in the response to the file open request to the host.
The step of acquiring the mapping information is:
Determining the range of mapping information to be sent to the host when the meta server receives a file open request from the host;
The file management method according to any one of claims 1 to 3, further comprising the step of the meta server acquiring the mapping information of the determined range from the mapping information storage unit.
The meta server determines, in the step of determining the range of the mapping information, mapping information corresponding to a data range which is likely to be accessed by the host after the file is opened as the range of the mapping information to be transmitted to the host. The file management method according to Item 4.
The mapping information includes a data range in the file and an assignment to the storage device, and the meta server determines the range of the mapping information in the step of: In the step of determining as the range of the mapping information to be transmitted and acquiring the mapping information, the mapping information including the data range in the determined file from the mapping information storage unit in the data range in the file of the mapping information The file management method according to claim 4 or 5, wherein
In the step of determining the range of the mapping information, the meta server transmits, to the host, at least one of a data range of a predetermined size from the beginning of the file and a data range of a predetermined size from the end of the file. The file management method according to claim 6, which is determined as a range.
The meta server according to claim 6, wherein, in the step of determining the range of the mapping information, the data range in the file is determined with reference to a rule that defines a data range to be transmitted to the host at the time of file open. File management method.
The meta server records a history of mapping information acquisition requests sent by the host at the time of file access;
9. The file management method according to claim 8, further comprising the step of: the meta server referring to the history to determine a data range to be transmitted to the host at the time of the file open in the rule.
A metaserver that manages mapping information that manages allocation of data that constitutes a file to a storage device, comprising:
A mapping information acquisition unit that acquires mapping information of a file to be opened from a mapping information storage unit that stores the mapping information when there is a file open request from the host;
A mapping information transmission unit that transmits the mapping information acquired by the mapping information acquisition unit to the host.
The meta server according to claim 10, wherein the mapping information transmission unit transmits the response to the file open request including the mapping information acquired by the mapping information acquisition unit to the host.
It further comprises an open time mapping information return range determination unit that determines the range of mapping information to be sent to the host when the file is opened,
The meta server according to claim 10, wherein the mapping information acquisition unit acquires mapping information of the range determined by the open mapping information return range determination unit from the mapping information storage unit.
13. The open-ended mapping information return range determination unit according to claim 12, wherein the mapping information corresponding to the data range that the host is likely to access after the file is opened is determined as the range of the mapping information to be transmitted to the host. Meta server.
The mapping information includes a data range in the file and an assignment to the storage device, and the open time mapping information return range determining unit is configured to transmit the data range in the file to be opened to the host. The mapping information acquisition unit determines the data range in the file determined by the open mapping information return range determination unit from the mapping information storage unit to the data range in the file of the mapping information. The meta server according to claim 12 or 13, which acquires mapping information including.
The open time mapping information return range determination unit determines at least one of a data range of a predetermined size from the beginning of the file and a data range of a predetermined size from the end as a range of mapping information to be transmitted to the host. The meta server according to claim 14.
The meta server according to claim 14 or 15, wherein the open time mapping information return range determination unit determines a data range in the file with reference to a rule that defines a data range to be transmitted to the host when the file is opened. .
A history generation unit for recording a history of mapping information acquisition requests transmitted by the host at the time of file access;
The meta server according to claim 16, further comprising: a rule generation unit in the rule that determines a data range to be transmitted to the host when the file is opened with reference to the history.
It is a meta server which manages mapping information which manages allocation of data constituting a file to a storage apparatus, and when there is a file open request from the host, mapping information of the file to be opened from the mapping information storage unit which stores the mapping information. A meta-server having a mapping information acquisition unit for acquiring the mapping information, and a mapping information transmission unit for transmitting the mapping information acquired by the mapping information acquisition unit to the host;
A file management system comprising: a host having a mapping information cache that registers mapping information sent from the meta server in a cache when the file is opened.
A program for a file system having a meta server for managing mapping information for managing allocation of data constituting a file to a storage device, the meta server comprising
A process of acquiring mapping information of a file to be opened from a mapping information storage unit that stores mapping information when receiving a file open request from a host;
A program for executing processing for transmitting the acquired mapping information to the host.