JP2010237956A - Virtual disk compression device, method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a difference data compression device for reducing the size of a difference data file by deleting data from difference data if remodel of a system of a guest operating system side is not needed and if a data area present in the difference data is not used, in a difference data management method. <P>SOLUTION: In the difference data compression device, an update position information file 173 records the block position information of update data when a virtual machine 110 updates data in a virtual disk 115. An update position information acquisition means 161 obtains the block position information from the update position information file 173. A use situation confirmation means 162 accesses the virtual disk 115 through a virtual environment base software 150, analyzes a file system constructed in the virtual disk 115, and checks the use situation of a block corresponding to the block position information obtained. If an unused region is recognized, a difference data deletion means 163 deletes data of a corresponding block number from the difference data file 172 and the update position information file 173. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a virtual disk compression apparatus, method, and program, and more particularly, to a virtual disk compression apparatus, method, and program for compressing a file on a physical disk corresponding to a virtual disk accessed by a virtual machine. .

  There is a virtualization technology that operates a virtual machine on a real computer. An OS (operating system) that controls the operation of a real computer is called a host OS, and an OS that operates on a virtual machine is called a guest OS. The virtual machine accesses a virtual storage device (virtual disk) that is a logical storage device. When viewed from the host OS, the virtual disk appears as a file recorded in a physical storage device (physical disk).

  When the virtual machine accesses the virtual disk and writes data to the virtual disk, the virtual environment infrastructure that implements the virtual environment records the written data in a file on the physical disk. Here, the file on the physical disk does not have the data of all areas reserved as the virtual disk, but has the data of the area written in the virtual disk. Since no data is read from an unused area, data does not exist in the portion corresponding to the unused area of the file on the physical disk.

  When a virtual machine is operated, an area in which data has been recorded in the past may become an unused area later as a file is deleted or data is moved. Even in such a case, data in an area that has become an unused area is not deleted from the file on the physical disk. This is because the virtual environment infrastructure does not know where the virtual disk has become an unused area. Therefore, the file size of the file on the physical disk increases as the use of the virtual disk proceeds.

  Several methods for reducing disk capacity in virtual environments have been proposed. One of the methods for reducing the disk capacity in a virtual environment is that after defragmentation is executed on the guest OS, a mark indicating unused is written in an area that has been moved by defragmentation and is unused, and exists on the host OS. There is a method of detecting an unused area using a compression utility that deletes data from a virtual disk (see, for example, Patent Document 1).

JP 2008-234268 A

  There is a technique for managing a virtual disk accessed by a virtual machine using a differential method. In the difference data management method in the virtual machine system, data is managed by master data and difference data. When the virtual machine updates the file, the update data is written to the difference data. When reading the file, if the requested difference data is in the difference data, the data is read from the difference data. If the requested data is not present in the difference data, the data is read from the master data.

  In Patent Document 1, an area that has become an unused area due to file movement after defragmentation is deleted. However, when the defragmentation is executed by the difference data management method, writing to the difference data occurs along with the data movement from the master data area, and the difference data is expanded. Therefore, in the method for managing the difference data, defragmentation is prohibited.

  Moreover, in patent document 1, the information which shows that it is an unused area | region is written with respect to a data deletion recording area at the time of data deletion. Even in this method, when data existing in the master data is deleted, writing to the difference data occurs, and the difference data temporarily increases until the compression utility is executed on the host OS. The unused area is managed by a file system built in the host OS. When a file is deleted, only the management area of the file system is rewritten, and the disk itself is not cleared. For this reason, it is necessary to modify the file system to mark the unused area. In addition, there is a problem that overhead due to writing occurs.

  The present invention requires no modification to the system on the guest OS side, and when the data area existing in the differential data becomes unused by the differential data management method, the data is deleted from the differential data and the differential data file An object is to provide a differential data compression apparatus, method, and program capable of reducing the size.

  In order to achieve the above object, according to the present invention, a virtual storage device, which is a logical storage device accessed by a virtual machine, has a master data file and a differential data file in a physical storage device accessed by a host OS (operating system). Update position information acquisition means for acquiring the block position information from an update position information file that records block position information of update data when the virtual machine updates data in the virtual storage device , Access to the virtual storage device through virtual environment infrastructure software for realizing a virtual environment on a computer, analyze a file system constructed in the virtual storage device, and use state of a block corresponding to the acquired block position information Corresponding to the usage status confirmation means for checking the block position information obtained above When the block is determined to be an unused area, a differential data compression apparatus is provided that includes a data deletion unit that deletes data of a corresponding block number from the differential data file and the update location information file To do.

  In the present invention, a virtual storage device, which is a logical storage device accessed by a virtual machine, is composed of a master data file and a differential data file in a physical storage device accessed by a host OS (operating system). Acquiring the block position information from an update position information file that records block position information of update data when the virtual machine updates data in the virtual storage device; and Accessing the virtual storage device through virtual environment infrastructure software for realizing an environment, analyzing a file system constructed in the virtual storage device, and examining the use status of the block corresponding to the acquired block position information; The acquired block position by the computer When the block corresponding to the information is determined to be an unused area, a differential data compression method comprising: deleting the data of the corresponding block number from the differential data file and the update position information file is provided. .

  In the present invention, a virtual storage device, which is a logical storage device accessed by a virtual machine, is composed of a master data file and a differential data file in a physical storage device accessed by a host OS (operating system). In addition, a process for obtaining the block position information from an update position information file that records block position information of update data when the virtual machine updates data in the virtual storage device, and realizing a virtual environment on the computer A process of accessing the virtual storage device through virtual environment infrastructure software, analyzing a file system constructed in the virtual storage device, and checking a usage status of a block corresponding to the acquired block position information; and the acquired block Judge that the block corresponding to the location information is an unused area When, with the differential data file, from said update position information file, to provide a program for executing the processing for deleting the data of the corresponding block number.

  The virtual disk compression apparatus, method, and program according to the present invention provide differential data when the data area existing in the differential data becomes unused in the differential data management system without any modification to the system on the guest OS side. Data can be deleted from the file to reduce the size of the differential data file.

The block diagram which shows the virtual environment execution apparatus containing the difference data compression apparatus of one Embodiment of this invention. The block diagram which shows the structure of a virtual disk. The flowchart which shows the operation | movement procedure of difference data compression.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a computer including a differential data compression apparatus according to an embodiment of the present invention. The computer (host computer) incorporates an operating system (host OS) that controls the operation of the entire computer. The host computer includes virtual environment infrastructure software 150, differential data compression utility 160, and virtual side physical disk 170. The host computer operates according to the program of the differential data compression utility 160, thereby realizing the function of the differential data compression apparatus.

  The virtual environment infrastructure software 150 is software that operates on the host OS, and is software that implements a virtual machine on the host computer. The host OS has a function of providing a virtual environment. The guest OS is an operating system that operates in a virtual environment, and is installed in the virtual machine 110.

  The virtual machine 110 includes an application 111, a guest OS 112, and a virtual disk 115. The guest OS 112 has a file system 113 and a disk driver 114. The application 111 is user space application software that runs on the guest OS 112. The virtual disk 115 is a logical storage device used in the guest OS. The file system 113 is a module that manages a file and an arrangement on a disk where data is written. The disk driver 114 is a driver module for the guest OS 112 to read and write the virtual disk 115.

  The configuration of the virtual machine 120 is the same as that of the virtual machine 110. That is, the virtual machine 120 includes an application 121, a guest OS 122 including a file system 123 and a disk driver 124, and a virtual disk 125. Although not shown in FIG. 1, the virtual machines 130 and 140 have the same configuration as the virtual machines 110 and 120, and include an application, a guest OS, and a virtual disk.

  FIG. 2 shows the configuration of the virtual disk. The virtual disk 115 of the virtual machine 110 includes a master data file 116 and a difference data file 117. The virtual disk 115 is a disk virtualized by the virtual environment infrastructure software 150, and is treated as a normal recording device by the guest OS 112. The virtual disk 115 is managed by dividing the disk into a plurality of blocks.

  The data on the virtual disk 115 is managed by the difference data management method. The master data file 116 is a file in which an OS, an application, and the like that operate in a virtual machine are installed, and is used exclusively for reading data. The difference data file 117 is written with data when the data is updated.

  When the application 111 or the like performs a read operation on a block written in the master data file 116, the guest OS 112 (FIG. 1) reads data from the master data file 116. On the other hand, when a read operation is performed on a block written in the differential data file 117, the guest OS 112 reads data from the differential data file 117.

  The virtual machines 120, 130, and 140 are virtual machines derived from the virtual machine 110. The virtual disk 125 of the virtual machine 120 includes a master data file 126 and a difference data file 127. The virtual disk 135 of the virtual machine 130 includes a master data file 136 and a difference data file 137. The virtual disk 145 of the virtual machine 140 includes a master data file 146 and a difference data file 147.

  The master data files 116, 126, 136, and 146 are files common to the respective virtual machines. Actually, one master data file exists in the system. In FIG. 2, the master data files 126, 136, and 146 are the master data file 116. The virtual disk of each virtual machine is composed of a master data file common to the virtual machines and a differential data file unique to each virtual machine.

  Returning to FIG. 1, the virtual physical disk 170 is a physical disk drive accessed by the host computer. The master data file 171 corresponds to the master data files 116, 126, 136, and 146 in FIG. The difference data file 172 corresponds to the difference data file 117 in the virtual disk 115 of the virtual machine 110. The difference data file 174 corresponds to the difference data file 127 in the virtual disk 125 of the virtual machine 120.

  The update position information file 173 is a file in which block numbers of data updated in the virtual disk 115 of the virtual machine 110 are recorded. When the application 111 updates a file existing on the file system, the virtual environment infrastructure software 150 writes update data to the differential data file 172 in the virtual physical disk 170 and updates the update location information file 173. Record the block number. The update location information file 175 is a file corresponding to the virtual machine 120, and is a file that records the block number of the updated data, like the update location information file 173.

  The differential data compression utility 160 is utility software that reduces the file size of the differential data file (compresses the differential data file). The differential data compression utility 160 accesses the differential data file and the update location information file on the virtual physical disk 170 corresponding to the target virtual machine and the virtual disk in the virtual machine through the virtual environment infrastructure software 150. Execute compression of differential data file.

  The differential data compression utility 160 includes an update position information acquisition unit 161, a usage status confirmation unit 162, and a data deletion unit 163. The update position information acquisition unit 161 acquires the block number of the update data from the update position information files 173 and 175. The usage status confirmation unit 162 accesses the virtual disks 115 and 125 through the virtual environment infrastructure software 150, and whether the virtual disk area corresponding to the block number acquired by the update position information acquisition unit 161 is an in-use area or an Determine if it is an area of use. The data deletion unit 163 deletes the data of the block number determined to be unused by the usage status confirmation unit 162 from the difference data file 172 and deletes the block number from the update position information files 173 and 175.

  For example, assume that the compression target is the differential data file 172 corresponding to the virtual machine 110. The update position information acquisition unit 161 acquires the block number of the update data from the update position information file 173 in which the update position information is recorded. The usage status confirmation unit 162 analyzes the usage status of the block in the virtual disk 115 corresponding to the block number of the acquired update data by analyzing the file system constructed in the virtual disk 115. The data deletion unit 163 deletes the data of the corresponding block number from the difference data file 172 and the update position information file 173 when the block usage status corresponds to unused.

  FIG. 3 shows an operation procedure when the differential data file is compressed. Hereinafter, the compression of the differential data file 172 corresponding to the virtual machine 110 will be described as an example, but the operation procedure is the same for other virtual machines. The differential data compression utility 160, via the virtual environment infrastructure software 150, exists in the virtual physical disk 170 on the host OS side, the differential data file 172 and the update location information file 173 corresponding to the virtual machine 110, and the virtual disk 115. Are opened (step A1).

  The update position information acquisition unit 161 acquires a list of updated block numbers from the update position information file 173 (step A2). The update position information acquisition unit 161 extracts block numbers one by one from the acquired list one by one and passes them to the usage status confirmation unit 162. The usage status checking unit 162 accesses the virtual disk 115 through the virtual environment infrastructure software 150 and checks the usage status on the file system of the block corresponding to the block number received from the update location information acquisition unit 161 (step A3). .

  The usage status confirmation unit 162 determines whether the usage status on the file system is an unused area (step A4). When the use status confirmation unit 162 determines that the usage status confirmation unit 162 is an unused area, the data deletion unit 163 clears the data of the corresponding block number from the difference data file 172 and the update position information file 173 (step A5). The differential data compression utility 160 takes out block numbers one by one from the list and executes steps A3 to A5 until the end of the list of block numbers acquired at step A2 is reached.

  The minimum configuration of the present invention will be described. The minimum configuration of the present invention is a portion of the differential data compression utility 160. The differential data compression utility 160 includes an update position information acquisition unit 161, a usage status confirmation unit 162, and a data deletion unit 163. The virtual disk is a logical storage device accessed by the virtual machine, and is composed of a master data file 171 and differential data files 172 and 174 in the virtual physical disk 170 accessed by the host OS. The update position information files 173 and 175 are files for recording block position information of update data when the virtual machine updates data in the virtual disk. The update position information acquisition unit 161 acquires block position information from the update position information file. The usage status checking unit 162 accesses the virtual disk through the virtual environment infrastructure software 150, analyzes the file system built on the virtual disk, and checks the usage status of the block corresponding to the acquired block position information. When the use status checking unit 162 determines that the usage status check unit 162 is an unused area, the data deletion unit 163 deletes the data of the corresponding block number from the difference data file and the update position information file.

  The differential data compression utility 160 is software that runs on the host OS, and the differential data file compression function can be realized by software that runs on the host OS. The operation on the guest OS side is a normal operation, and the system on the guest OS side does not need to be modified when compressing the differential data file. In the present invention, when the update data in the virtual disk 115 is recorded in the differential data file in the virtual physical disk 170, the block position information of the update data is recorded in the update position information file. When compressing the differential data file, the file system constructed on the virtual disk is analyzed through the virtual environment infrastructure software 150, and the usage status of the area in the virtual disk corresponding to the block position information recorded in the update position information file is examined. . If the file system built on the virtual disk is an unused area, the data of the corresponding block position information can be deleted to compress the differential data file.

  Although the present invention has been described based on the preferred embodiment, the differential data compression apparatus, method, and program of the present invention are not limited to the above embodiment, and the configuration of the above embodiment. Various modifications and changes are also included in the scope of the present invention.

  The present invention can be applied to a thin client system that requires construction of a virtual environment with limited resources. Furthermore, the present invention is a virtual environment system that manages master data and difference data, and can be applied to a relatively large-scale system having a large number of virtual machines.

110, 120, 130, 140; virtual machine 111, 121: application 112, 122, 132, 142: guest OS
113, 123: File systems 114, 124: Disk drivers 115, 125, 135, 145: Virtual disk 150: Virtual environment infrastructure software 160: Differential data compression utility 161: Update position information acquisition means 162: Usage status confirmation means 163: Data Deletion means 170: Virtual side physical disk 171: Master data file 172, 174: Difference data file 173, 175: Update location information file

Claims (3)

A virtual storage device that is a logical storage device accessed by a virtual machine is composed of a master data file and a differential data file in a physical storage device accessed by a host OS (operating system),
Update position information acquisition means for acquiring the block position information from an update position information file that records block position information of update data when the virtual machine updates data in the virtual storage device;
The virtual storage device is accessed through virtual environment infrastructure software for realizing a virtual environment on the computer, the file system constructed in the virtual storage device is analyzed, and the usage status of the block corresponding to the acquired block position information is determined. Use status checking means to check;
When it is determined that the block corresponding to the acquired block position information is an unused area, data deletion means for deleting data of the corresponding block number from the difference data file and the update position information file; A differential data compression apparatus comprising: A virtual storage device that is a logical storage device accessed by a virtual machine is composed of a master data file and a differential data file in a physical storage device accessed by a host OS (operating system),
A computer acquiring the block position information from an update position information file that records block position information of update data when the virtual machine updates data in the virtual storage device;
The computer accesses the virtual storage device through virtual environment infrastructure software that realizes a virtual environment on the computer, analyzes a file system constructed in the virtual storage device, and corresponds to the acquired block position information A step to check the usage of
When the computer determines that the block corresponding to the acquired block position information is an unused area, deleting the data of the corresponding block number from the difference data file and the update position information file; A differential data compression method. A virtual storage device that is a logical storage device accessed by a virtual machine is composed of a master data file and a differential data file in a physical storage device accessed by a host OS (operating system),
On the computer,
Processing for acquiring the block position information from an update position information file that records block position information of update data when the virtual machine updates data in the virtual storage device;
The virtual storage device is accessed through virtual environment infrastructure software for realizing a virtual environment on the computer, the file system constructed in the virtual storage device is analyzed, and the usage status of the block corresponding to the acquired block position information is determined. The process of examining,
When determining that a block corresponding to the acquired block position information is an unused area, a program for executing a process of deleting data of the corresponding block number from the difference data file and the update position information file .

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