JP2006146389A - Access method to remote storage device system using storage device virtualization function in operating system, host computer for the same, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for stably and quickly performing access to a remote storage device system by minor change to an operating system without adding any change to every application. <P>SOLUTION: This host computer 1 is provided with an initiator function 11 of performing access to a remote storage device system 4 in the same way as a normal storage device 2 directly connected to a host computer 1 and a storage device virtualization function 7 of providing the normal storage device 2 and the remote storage device system 4 to an application as a virtual storage device. The storage device virtualization function 7 temporarily stores data in the normal storage device 2 according to a write instruction from an application 5 of the host computer 1. Then, the storage device virtualization function 7 reads data temporarily stored in the normal storage device 2, and stores the data through the initiator function 11 in the remote storage device system 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for accessing a storage system in a remote location, a host computer therefor, and a program.

  The host computer can be configured to store data in a storage device system that is assigned to a physically remote location and connected by a dedicated line or a public line.

  In this case, the state of the network line between the host computer and the remote storage device system, that is, the available bandwidth and the delay time are not constant. In a state where the bandwidth becomes small or the delay time becomes long, access from the host computer to the network storage is hindered. Specifically, the reading / writing speed of the remote storage system decreases.

  In response to the above-mentioned problems, the data required by the application is predicted in advance, and the time required for the application read instruction is reduced by transferring the data from the remote storage system to the host computer in advance. A technique called prefetching is used.

Regarding writing, data updated by an application is written to a network buffer in an operating system running on the host computer or a buffer called a page cache, and transferred according to the speed of the network.
As prior art documents related to the present invention, there are the following.

Maki Tanikawa and two others, “Proposal of Stream Broadcast Management System Architecture for Broadband Streaming Broadcast Networks”, Proceedings of the 2003 IEICE General Conference, B-7-24 (page 284), March 19, 2003 Patent Document 2 Seiyoshi Takase and three others, “Examination of shapers suitable for iSCSI data traffic”, Proceedings of the 2004 IEICE Communication Society Conference, B-7-61 (200 pages), September 21, 2004

  A problem in the above-described system is that existing operating systems such as Unix and Windows assume that writing to a storage device is completed to a certain extent at high speed.

  Therefore, if a large amount of data is written in a situation where the network state has deteriorated, the operating system becomes unstable. Specifically, a function called page cache that temporarily stores data written by applications consumes most of the physical memory of the host computer, causing the operating system and applications to run out of memory, causing the system to stop. It becomes.

  In addition, there is a problem that all data held in the physical memory is lost due to a failure such as a power failure. Therefore, storing a large amount of data in such a buffer is undesirable from an application perspective. Another problem is that the physical memory used for the buffer is more expensive than the storage device system.

  As a conventional technique for solving the above-described problems, a change is made to an existing application that does not assume that the storage device is remotely located, the network state is monitored, and the data write amount is adjusted. There is a method for implementing a function (for example, see Non-Patent Document 1). This method has a problem that a cost for making a change for each application occurs. In addition, when the writing speed required by the application exceeds the network speed, the writing must be temporarily stopped so as not to run out of physical memory.

  As a conventional technology other than those described above, an ordinary storage device that is directly connected to the host computer via a bus or the like and guarantees stable access performance is used as a temporary storage area, and after the network state is improved, remote storage is performed. The method of saving in the device system is used. The capacity of the normal storage device used as a temporary storage area may be smaller than the capacity of the remote storage device system. By storing the data once in the normal storage device, the data updated by the application can be recovered using the data in the normal storage device even when a failure such as a power failure occurs. This method is called a buffer disk system. With the buffer disk function, the write data stored in the page cache can be discarded when writing to the normal storage device is completed. Therefore, if the capacity of the normal storage device is large enough, a system stoppage due to a lack of physical memory can be prevented. be able to.

  As a conventional mounting technique of the buffer disk system, there is a method of changing an existing application that does not assume a remote storage device system. This method has a problem in that the cost of making changes for each application is generated in the same manner as the method for adjusting the amount of writing by making changes for each application.

  As another existing mounting technique, as shown in FIG. 4, a function (initiator function 11) for realizing the same access as the normal storage device (storage device directly connected to the host computer) 2 to the remote storage device system 4 There is a method of adding the buffer disk function 10 by changing (refer to Non-Patent Document 2, for example). Since this method has only the network function 12 for the initiator function 11 to access the remote storage device system 4 and does not have the function for accessing the storage device, it is necessary to implement the necessary functions from scratch. There is a drawback that the implementation is enlarged.

  As another existing mounting technique, as shown in FIG. 5, by changing the network function portion 12 mounted on the operating system 6 operating on the host computer (see, for example, Non-Patent Document 1), the buffer disk There is a method of adding the function 10. Similar to the method of changing the initiator function 11, the network function 12 does not have a function for accessing the storage device, and thus has a drawback that the implementation is enlarged.

  4 and 5, 1 is a host computer, 3 is a network, 5 is an application, 7 is a disk virtualization function, 8 is a local disk, and 9 is a remote disk.

  It is possible to add a buffer disk function by running the same software as that running in the remote storage system on the host computer, but this method can copy data multiple times within the operating system. In order to generate | occur | produce, there exists a fault that performance falls.

The present invention has been made to solve the above-mentioned problems of the prior art, and the object of the present invention is to make a change to the remote storage device system by making a small change to the operating system without making a change for each application. It is to provide a technique for performing stable and high-speed access.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  In order to solve the above-described problem, in the present invention, a buffer disk function is added to a storage device virtualization function (hereinafter referred to as a disk virtualization function) provided by an operating system that operates on a host computer.

  The operating system recognizes the storage device as a physical disk. The disk virtualization function provides a function for linking this physical disk and a virtual disk accessed by an application. In the simplest case, a physical disk and a virtual disk are associated one to one. In addition, an operating system such as UNIX or Windows provides a virtualization function such as a function of combining two physical disks into one virtual disk having a large capacity.

  In this method, a buffer disk function is implemented as one of the functions provided by such a disk virtualization function. With the initiator function, the remote storage device system can be accessed as a physical disk just like a directly connected storage device. Therefore, the disk virtualization function can be accessed without distinguishing between the normal storage device and the remote storage device system. The disk virtualization function has a function of accessing a physical disk, and the buffer disk function can access both the normal storage device and the remote storage device system by using the function. Therefore, it is possible to reduce the mounting amount for realizing the present technology.

  The application always accesses the virtual disk provided by the disk virtualization function and does not need to know how the virtual disk is configured. Therefore, even when this method is used, no change to the application occurs.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the present invention, it is possible to perform stable and high-speed access to a remote storage device system by making a small change to the operating system without making a change for each application.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram illustrating a schematic configuration of an information processing system according to an embodiment of this invention.

  In the figure, 1 is a host computer, 2 is a storage device directly connected to the host computer (sometimes referred to as “normal storage device” because it is a normal storage device directly connected to the host computer via a bus or the like), 3 Is a network line, 4 is a remote storage system connected by the network line 3, 5 is an application, 6 is an operating system, 7 is a disk virtualization function, and 8 is an identification name in the operating system of the storage device 2 A local disk, 9 is a remote disk which is an identification name in the operating system of the storage device of 4, 10 is a buffer disk function, 11 is an initiator function, and 12 is a network function for processing a network protocol.

  4 has a storage device, has a function of connecting to the host computer 1 via the network line 3, writes data to the storage device in accordance with a write command from the host computer 1, and sends a write completion notification to the host computer. 1 and a function of reading data from the storage device in accordance with a read command from the host computer 1 and transmitting it to the host computer. Usually, the storage capacity of the remote storage device system 4 is larger than the storage capacity of the normal storage device 2. The host computer 1 can access the remote storage device system 4 in the same manner as the normal storage device 2 by the initiator function 11 of the operating system 6. The “remote” of the remote storage device system 4 is not directly connected to the host computer 1 via a bus or the like like the normal storage device 2 but is connected to the host computer 1 via the network line 3. This means that even though it is usually geographically remote, it may be geographically close to the host computer.

  For convenience of explanation, it is specified that the remote disk 9 is a remote storage device, but the buffer disk function 10 can be accessed as a physical disk in exactly the same manner as the local disk 8.

FIG. 2 is a flowchart illustrating a data writing process from the application 5 in the information processing system according to the present exemplary embodiment.
The writing process is performed in two steps. First, in the first step, the application 5 writes data to the virtual disk provided by the disk virtualization function 7. As a result, the buffer disk function 10 receives the data and writes the data to the local disk.

  In the second step, the buffer disk function 10 copies data from the local disk to the remote disk. Usually, since the capacity of the local disk is smaller than that of the remote disk, the data that has been copied to the remote disk is deleted from the local disk as necessary.

The first step is a process indicated by steps 1010 to 1040 in FIG.
First, the writing from the application 5 reaches the disk virtualization function 7 (step 1010).

  The buffer disk function 10 receives data from the disk virtualization function 7 (step 1020) and writes the data to the local disk (step 1030). As a result, the data is stored in the directly connected storage device 2 (step 1040).

  The buffer disk function 10 records the disk position where the oldest data and new data are stored. Here, since the data has been added, the disk position of the latest data is updated.

The second step is a process indicated by steps 1050 to 1080 in the step of FIG.
The buffer disk function 10 issues a read request to the local disk 8 (step 1050), and reads data that has not yet been copied to the remote storage system 4 from the directly connected storage device 2. This can be accomplished using the disk location where the oldest data is stored.

  The buffer disk function 10 writes this data to the remote disk 9 (step 1060). As a result, the data reaches the remote storage device system 4 via the initiator function 11 and the network function 12 (step 1070).

The remote storage system 4 writes the data and sends a write completion notification to the host computer (step 1080).
When the buffer disk function 10 receives a write completion notification from the remote storage system 4, the buffer disk function 10 updates the disk position of the oldest data.

FIG. 3 is a flowchart illustrating a process for reading data from the application 5 in the information processing system according to this embodiment.
Similar to the writing process, the application 5 requests the virtual disk provided by the disk virtualization function 7 to read data. As a result, the disk virtualization function 7 receives the read command (step 2010) and passes it to the buffer disk function 10.

  The buffer disk function 10 receives the read command (step 2020), and checks whether the requested data is stored in the local disk 8 (step 2030).

  In step 2030, if the data is not stored in the local disk 8, that is, the directly connected storage device 2, the buffer disk function 10 issues a read command to the remote disk 9 (step 2040). As a result, the read command is transferred to the remote storage device 4 via the initiator function 11 and the network function 12.

  The remote storage device 4 sends the data to the host computer (step 2050), and the buffer disk function 10 receives the data via the network function 12 and the initiator function 11.

  If the data is stored in the local disk 8, that is, the directly connected storage device 2 in step 2030, the buffer disk function 10 issues a read command to the local disk 8 (step 2060). As a result, data is read from the directly connected storage device (step 2070).

  When receiving the necessary data, the buffer disk function 10 passes the data to the disk virtualization function. As a result, data is passed to the application 5 that issued the read command (step 2080).

  The host computer 1 and the remote storage system 3 described above have means for realizing the function or means for performing the operation, and the means executes a program created to realize the function or perform the operation. Is realized by executing.

  In this embodiment, the storage device virtualization means included in the operating system 6 of the host computer 1 temporarily stores data in the normal storage device 2 in accordance with a write command from the application 5 and then stores it in the normal storage device 2. The read data is read out and stored in the remote storage system 4 via the initiator means. Further, the storage device virtualization means included in the operating system 6 reads data from the remote storage device system 4 via the initiator means when the data is not stored in the normal storage device 2, and the data is stored in the normal storage device 2. If stored, the data is read from the normal storage device 2.

  Therefore, it is not necessary to make a change for each application, and the storage device virtualization means of the operating system has a function for accessing the storage device, so that it can be implemented with a small change to the operating system. Then, the data is temporarily stored in the normal storage device 2 that is directly connected to the host computer 1 via a bus or the like and that guarantees stable and high-speed access performance. Since the data can be stored in the large-capacity remote storage device system 4 via the network line 3 whose time is not constant, a large amount of data can be stored stably and at high speed. Furthermore, when data is read, if the data is stored in the normal storage device 2, the data is read from the normal storage device 2. Regardless of the state of the line 3, it can be read stably and at high speed. That is, according to the present embodiment, it is possible to stably and rapidly access the remote storage device system by making a small change to the operating system without making a change for each application.

  As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

It is a block diagram which shows schematic structure of the information processing system of the Example of this invention. It is a flowchart which shows the 1st step of the writing process of data. It is a flowchart which shows the 2nd step of the writing process of data. It is a flowchart which shows the reading process of data. It is a figure which shows the prior art which adds a buffer disk function to an initiator function. It is a figure which shows the prior art which adds a buffer disk function to a network function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Host computer, 2 ... Directly connected storage device (normal storage device), 3 ... Network, 4 ... Remote storage device system, 5 ... Application, 6 ... Operating system, 7 ... Disk virtualization function, 8 ... Local disk , 9 ... Remote disk, 10 ... Buffer disk function, 11 ... Initiator function, 12 ... Network function

Claims (5)

A method for accessing the remote storage device system in an information processing system comprising a host computer, a normal storage device directly connected to the host computer, and a remote storage device system connected to the host computer via a network. And
The host computer provides initiator means that can access the remote storage device system in the same manner as the normal storage device, and storage device virtualization that provides the normal storage device and the remote storage device system as virtual storage devices to an application. Means,
The storage device virtualization means for temporarily storing data in the normal storage device in accordance with a write command from an application of the host computer;
The storage device virtualization means reads the data temporarily stored in the normal storage device and stores the data in the remote storage device system via the initiator means;
A method for accessing a remote storage device system, comprising: A method for accessing a remote storage system according to claim 1, comprising:
The storage device virtualization means checks whether data is stored in the normal storage device according to a read command from an application of the host computer;
The storage device virtualization means reads the data from the remote storage system via the initiator means when the data is not stored in the normal storage device;
The storage device virtualization means reads the data from the normal storage device when the data is stored in the normal storage device;
A method for accessing a remote storage device system, comprising: A host computer in an information processing system comprising a host computer, a normal storage device directly connected to the host computer, and a remote storage device system connected to the host computer via a network,
Initiator means capable of accessing the remote storage device system in the same manner as the normal storage device, and storage device virtualization means capable of providing the normal storage device and the remote storage device system as virtual storage devices to an application. And
The storage device virtualization means
Means for temporarily storing data in the normal storage device in accordance with a write command from an application of the host computer;
Means for reading the data temporarily stored in the normal storage device and storing the data in the remote storage device system via the initiator means;
A host computer characterized by comprising: A host computer according to claim 3,
The storage device virtualization means
Means for checking whether data is stored in the normal storage device in accordance with a read command from an application of the host computer;
Means for reading the data from the remote storage device system when the data is not stored in the normal storage device;
Means for reading the data from the normal storage device via the initiator means when the data is stored in the normal storage device;
A host computer characterized by comprising:   A program for causing a computer to execute the means according to claim 3 or 4.

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