JP2006301905A - Data mirroring system and data mirroring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of holding a state in which consistency is maintained among a plurality of storage device systems and reducing a time for processing necessary for mirroring. <P>SOLUTION: A control unit 105 of a main storage device system 102 is provided with: a log logical volume management means 111 for storing in a log logical volume 107 data sent by a host computer 101 and information on a write order restriction; a write order restriction detection means 113 for detecting the information on the write order restriction stored in the log logical volume 107; and a mirroring means 112 for mirroring the data stored in the log logical volume 107 in a sub storage device system 103 by a write request designating write order when there is a write order restriction and by a write request not to designate write order when there is no write order restriction according to the information detected by the write order restriction detection means 113. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data mirroring system and a data mirroring method, and more particularly, to a remote mirroring system and a remote mirroring method for mirroring data from a primary storage system to a secondary storage system remote from the primary storage system. And effective technology.

  2. Description of the Related Art Conventionally, an information processing system including a host computer and a plurality of storage devices stores data that the user desires to store in the long term in the storage device. Then, in response to a request from the user, the requested data is read from the storage device, thereby enabling long-term use of the data.

  Further, in the information system, in order to prevent the data written in the storage device from being lost, when the data is written in one storage device connected to the host computer, the same data is generally written in another storage device. Is. As described above, as a method for storing one data in each of a plurality of storage devices, for example, there is a method called remote mirroring.

  Remote mirroring is a method of copying data between a plurality of storage device systems located in geographically distant locations without using a host computer and storing the data in two locations. The storage device system is a system including a plurality of storage devices and a controller that controls the storage devices.

  In an information processing system that performs remote mirroring, storage device systems installed at geographically distant locations are interconnected by a network line such as a dedicated line or a public line. Of the logical storage areas (hereinafter referred to as logical volumes) possessed by a certain storage device system, a logical volume having the same capacity as the logical volume to be mirrored by remote mirroring is secured in the mirror storage destination storage device system. The Hereinafter, a logical volume that is a target of remote mirroring is referred to as a mirroring source logical volume, and a logical volume that is secured in a storage destination storage system is referred to as a mirroring destination logical volume.

  The mirroring destination logical volume is formed so as to have a one-to-one correspondence with the mirroring source logical volume. Then, the data of the mirroring source logical volume is copied to the mirroring destination logical volume via the network line. Also. When the data recorded in the mirroring source logical volume is updated, the updated data is sent via the network line. Copied to the mirroring destination logical volume.

  There are two types of remote mirroring classification methods: synchronous and asynchronous. In the asynchronous method, when the host computer instructs the primary storage system to update data, the primary storage system does not send the data to the secondary storage system, that is, the data recorded in the mirroring destination logical volume. When the update of the mirroring source logical volume is completed without updating, the completion of the update command is notified to the host computer. Thereafter, the primary storage system updates the data of the mirroring destination logical volume.

  In asynchronous remote mirroring, if the order in which the host computer updates the data in the mirroring source logical volume and the order in which those data are updated in the mirroring destination logical volume differ, the data recorded in the mirroring destination logical volume May not be available.

  When the file system operating on the host computer stores data in the mirroring source logical volume, the file system needs to update some data in the correct order. Therefore, if the data update order of the mirroring source logical volume is different from the order in which those data were updated on the mirroring destination logical volume, the data stored in the mirroring destination logical volume will differ from the state expected by the file system. , Will not be available.

  The basic method for avoiding the data destruction is to make the data update order of the mirroring source logical volume and the mirroring destination logical volume coincide. However, if the data update order of the mirroring destination logical volume is specified, the data update speed deteriorates and the mirroring speed also deteriorates.

  As a method of avoiding the specification of the data update order of the mirroring destination logical volume described above and avoiding data corruption, it is described in, for example, Japanese Patent Application No. 2004-1111014 (not known at the time of this application) by the present applicant. There is a method of using an instruction for mirroring control between a host computer, a primary storage device system, and a secondary storage device system.

  However, in such a method, the host computer, primary storage device system, and secondary storage device system need to understand the same mirroring control instruction. Therefore, there is a problem that two storage device systems that understand the same mirroring control command and new software and hardware must be newly installed in the host computer.

  As another method, using the data structure of the file system, the primary storage system determines whether or not the data needs to specify the data update order of the mirroring logical volume from the data contents updated by the host computer. There is a method of determining and ordering only some data updates (see Non-Patent Document 1).

Tomonari Fujita et al., “Asynchronous remote mirroring using the structure of journaling file system”, Information Processing Society of Japan, 98th System Software and Operating System Research Presentation, 2005-OS-98 (3), 2005/2 / 22

  However, in the case of the method described in Non-Patent Document 1, if the file system uses a complicated data structure, the data that needs to specify the data update order of the mirroring destination logical volume in the primary storage system There is a problem that the judgment of whether or not is complicated.

  An object of the present invention is to maintain a state of consistency among a plurality of storage device systems when performing mirroring, and even when data in one storage device system is lost, another storage device system It is possible to provide a technique capable of recovering data and reducing the processing time required for mirroring.

  According to a first aspect of the present invention, there is provided a host computer, a primary storage device system that is connected to the host computer and records and holds data from the host computer, and is connected to the primary storage device system and is held by the primary storage device system. A secondary storage system that records and holds a copy of the stored data, and the primary storage system includes a storage device having a primary logical volume that records and holds data from the host computer, and the primary logic from the host computer. A controller that controls data writing to a volume and mirroring (copying) of data performed between the secondary storage systems, and the secondary storage system copies logical volumes of the primary storage system. A storage device having a secondary logical volume for recording and holding is provided. The primary storage device system includes a storage device having a log logical volume used when mirroring data to the secondary storage device system, and the control device of the primary storage device system includes: Log logical volume management means for storing data sent from a host computer and information on write order restrictions in the log logical volume, and write order restriction detection for detecting information on write order restrictions saved in the log logical volume And the data stored in the log logical volume in accordance with the information detected by the write order restriction detection means, if there is a write order restriction and there is no write order restriction by a write request specifying the write order. Write request without specifying the write order More, characterized in that it and a mirroring control means for mirroring the secondary storage system.

  The second invention is the data mirroring system of the first invention, wherein the log logical volume management means is information indicating a write position to the logical volume in addition to the data and the information related to the write order restriction. Write position information and a data length that is the length of the data are stored in the log logical volume.

  A third invention is the data mirroring system according to the second invention, wherein the data, the information related to the write order restriction, the write position information, and the data length are cyclically stored in the log logical volume. It is characterized by storing.

  A fourth aspect of the present invention is the data mirroring system according to any one of the first to third aspects, wherein the information related to the write order restriction is a standard function of a protocol for connecting the host computer and the primary storage device system. It is information regarding the presence or absence of a data synchronization option provided.

  According to a fifth aspect of the present invention, there is provided a host computer, a primary storage device system connected to the host computer and recording and holding data from the host computer, and connected to the primary storage device system and held by the primary storage device system. A secondary storage system that records and holds a copy of the stored data, and the primary storage system includes a storage device having a primary logical volume that records and holds data from the host computer, and the primary logic from the host computer. A controller that controls data writing to a volume and mirroring (copying) of data performed between the secondary storage systems, and the secondary storage system copies logical volumes of the primary storage system. A storage device having a secondary logical volume for recording and holding is provided. A data mirroring method in a data mirroring system, wherein the primary storage device system includes a storage device having a log logical volume used when mirroring data to the secondary storage device system, and the control of the primary storage device system The apparatus includes log logical volume management means, write order restriction detection means, and mirroring control means, and the log logical volume management means sends data and write order restriction information sent from the host computer to the log logical volume. Storing the information stored in the log logical volume, and the mirroring control unit storing the data stored in the log logical volume. , The writing order According to the information detected by the limit detection means, a step of mirroring the secondary storage system by a write request specifying the write order when there is a write order limit or a write request not specifying the write order when there is no write order limit And.

  According to the present invention, it is possible to maintain a consistent state among a plurality of storage device systems and to recover data in another storage device system even when data in one storage device system is lost. In addition, the processing time required for mirroring can be shortened.

  FIG. 1 is a diagram showing a schematic configuration of a data mirroring system according to an embodiment of the present invention.

  In FIG. 1, 101 is a host computer, 102 is a primary storage system, 103 is a secondary storage system, 104 is a network (for example, the Internet), 105 is a control unit, 106 is a primary logical volume, 107 is a log logical volume, and 108 is It is a secondary logical volume. The primary logical volume 106 and the log logical volume 107 are stored in the storage device of the primary storage device system 102, and the secondary logical volume 108 is stored in the storage device of the secondary storage device system 103. The data mirroring system according to the present embodiment is an asynchronous remote mirroring system, and by using characteristics specific to the file system, the primary logical volume 106 of the primary storage system 102 and the secondary logical volume 108 of the secondary storage system 103 are used. Even when the data in one storage device system is lost, the data can be recovered in the other storage device system.

  In the data mirroring system of this embodiment, as shown in FIG. 1, a host computer 101 and a primary storage device system 102 are connected by a cable, for example, and the primary storage device system 102 and the secondary storage device system 103 are connected via a network 104. Connected. The primary storage system 102 records and holds data from the host computer 101, and the secondary storage system 103 records and holds a copy of the data held by the primary storage system 102.

  The primary storage system 102 stores the difference between the primary logical volume 106 that records and holds data from the host computer 101 and the data (logical volume) that is mirrored to the secondary storage system 103, that is, the primary logical volume 106 and the secondary logical volume 108. A log logical volume 107 for recording and holding, and a control device 105 are provided.

  In response to a read / write request from the host computer 101, the control device 105 of the primary storage system 102 has a primary logical volume management unit 110 that reads / writes data in the primary logical volume 106 and a log logic that manages the log logical volume 107. Volume management means 111, mirroring means 112 for transferring (mirroring) data stored in the log logical volume 107, and data necessary for the data of the secondary logical volume 108 to maintain consistency as a file system at the time of mirroring And a writing order restriction detecting unit 113 for detecting the writing order restriction.

  The log logical volume management unit 111 of the control device 105 manages the log logical volume 107 as a circular log structure. The log logical volume management unit 111 records a new log structure in the log logical volume 107 in order for each write from the host computer 101. Thereby, a plurality of log structures are cyclically stored in the log logical volume 107 in the order of writing. FIG. 2 shows an example of one log structure. One log structure 120 includes write position information 121, data length 122, presence / absence of data synchronization option 123, and data 124. The write position information 121 is information related to the write position to the logical volume designated by the host computer 101. The data length 122 is information on the data length of the data 124. In this embodiment, the presence / absence 123 of the data synchronization option is a binary value of “yes / no” specified by the file system operating on the host computer 101, but is not limited to this, and writing of a write command from the host computer 101 is not limited thereto. Any information regarding order restriction may be used. The log logical volume management unit 111 holds the beginning and end positions of the log logical volume 107. The head position is a position for holding the log structure containing the write data sent from the host computer 101 most recently, and the tail position is the position for holding the log structure containing the data sent the oldest. .

  The secondary storage system 103 includes a secondary logical volume 108 that stores a copy of the data of the primary logical volume 106, and updates the secondary logical volume 108 in response to a write command from the primary storage system 102.

  The operation of the data mirroring system of the present embodiment will be described with the state where the data recorded and held in the primary logical volume 106 and the secondary logical volume 108 are synchronized as an initial state.

  When the primary storage system 102 receives a write command from the host computer 101, the primary logical volume management means 110 of the control device 105 of the primary storage system 102 sends the data sent to the designated position of the primary logical volume 106. Start writing. Further, the log logical volume management unit 111 of the control device 105 writes the log structure 120 including the write position information 121, the data length 122, the presence / absence of the data synchronization option 123, and the data 124 to the head position of the log logical volume 107, and logs The head position of the log logical volume 107 is advanced by the data amount of the log structure 120 written to the logical volume 107 (the total data amount of the write position information 121, data length 122, data synchronization option presence / absence 123, and data 124). When the writing to the primary logical volume 106 and the log logical volume 107 is completed, the primary storage system 102 notifies the host computer 101 of the completion of the write command.

  In this embodiment, the data synchronization option of the write command from the host computer 101 uses the data synchronization option provided as a standard function of the protocol for connecting the host computer 101 and the primary storage system 102. For example, when the host computer 101 and the primary storage system 102 are connected using the iSCSI protocol, they are specified using a function called Task Attribute. This function is a standard function of the iSCSI protocol.

  In the case of performing mirroring, the log logical volume management unit 111 of the control device 105 of the primary storage device system 102 has only the data length 122 recorded in the log structure 120 stored at the end position of the log logical volume 107. Data 124 is read. The mirroring unit 112 transmits a write command for the data 124 read by the log logical volume management unit 111 to the secondary storage system 103. At this time, if the presence / absence 123 of the data synchronization option in the log structure 120 is valid according to the information detected by the write order restriction detection unit 113, a write request specifying the write order (update order) is requested. If the presence / absence 123 of the data synchronization option is not valid, a write request without designating the write order (update order) is requested.

  When the primary storage system 102 and the secondary storage system 103 are connected using the iSCSI protocol, it is possible to specify writing with an update order specified using a function called Task Attribute. As described above, since this function is an iSCSI protocol standard function, that is, a feature unique to the file system is used, the secondary storage system 103 does not need a special function for the mirroring method of this embodiment. .

  The secondary storage system 103 updates the data in the secondary logical volume 108 in accordance with the write command from the primary storage system 102. When a write with a specified write order is requested, the data update is started after all the data updates to the secondary logical volume 108 of the previously received write command are completed. When a write request for which the write order is not specified is requested, the secondary storage system 103 processes a plurality of received write commands in any order. For example, a plurality of write commands are processed in parallel. When the data update is completed, a write completion notification is transmitted to the primary storage system 102.

  When a write with a specified write order is requested, the secondary storage system 103 starts the data update after all the data updates to the secondary logical volume 108 of the previously received write command are completed. Processing time is required. On the other hand, when a write request for which the write order is not specified is requested, the secondary storage system 103 can process a plurality of received write commands in any order, so there is no waiting time and the processing time is short. .

  In this embodiment, only data for which the data synchronization option is specified at the time of a write command from the host computer 101 to the primary storage device system 102 is subjected to remote mirroring from the primary storage device system 102 to the secondary storage device system 103. By specifying the writing order and writing, it is ensured that the data copied to the secondary logical volume 108 is in a consistent state as a file system, and the processing time required for mirroring can be shortened.

  When the log logical volume management unit 111 of the primary storage system 102 receives the write completion notification from the secondary storage system 103, the log structure 120 including the data written to the secondary storage system 103 at the end of the log logical volume 107. The data amount (the total data amount of write position information 121, data length 122, presence / absence of data synchronization option 123, and data 124) is advanced in the head direction.

  When the start and end positions of the log logical volume 107 are not the same, the control device 105 of the primary storage system 102 starts mirroring again. Further, when the beginning and the end are the same, it means that the primary logical volume 106 and the secondary logical volume 108 are synchronized.

  3 and 4 are flow charts for explaining a data mirroring method using the data mirroring system of this embodiment. FIG. 3 is a flowchart showing a write processing method from the host computer 101 in the primary storage system 102. FIG. 4 is a flowchart showing a procedure for mirroring data from the primary storage system 102 to the secondary storage system 103. is there.

  As shown in FIG. 3, the primary storage system 102 receives a data write command from the host computer 101 (step 302). Next, the primary logical volume management means 110 of the control device 105 starts writing to the primary logical volume 106 (step 303). Subsequently, the log logical volume management unit 111 transfers the log structure 120 including the data write position information 121 of the volume, the data length 122, the information 123 regarding the presence / absence of the data synchronization option of the write command, and the data 124 to the head of the log logical volume 107. (Step 304). The control device 105 waits for completion of writing to the primary logical volume 106 and the log logical volume 107 (step 305). When the writing of the primary logical volume 106 and the log logical volume 107 is completed, the log logical volume management unit 111 increases the head position of the log logical volume 107 by the amount of data written to the log logical volume 107 (step 306). The control device 105 notifies the host computer 101 of the completion of writing (step 307).

  As shown in FIG. 4, the log logical volume management means 111 of the control device 105 of the primary storage system 102 checks the position of the beginning and end of the log logical volume 107, and if they are different, starts mirroring (step 402). . The log logical volume management unit 111 reads the log structure 120 from the end position of the log logical volume 107 (step 403), and reads the data 124 by the data length 122 recorded in the log structure 120 (step 404). ). The mirroring unit 112 of the control device 105 uses the write position information 121 of the log structure 120 to send a command to write the data read by the log logical volume management unit 111 to the secondary storage system 103. At this time, according to the information detected by the write order restriction detection means 113, the mirroring means 112, if the presence / absence 123 of the data synchronization option in the log structure 120 is valid, issues a write command in which the order designation option is designated. Use (step 405).

  The primary storage system 102 waits for a write completion notification from the secondary storage system 103 (step 406), and the log logical volume management unit 111 advances the end position of the log logical volume 107 by the data amount of the log structure 120 ( Step 407), returning to Step 401.

  As described above, in this embodiment, the synchronization option used when the host computer writes data to the primary storage system is also used during mirroring, so that the data can always be repaired during mirroring. Then, it is determined which data needs to specify the order of writing in the secondary storage device. In the conventional method, the primary storage system has instructed the secondary storage system to execute all data writing in the correct order, and thus the performance has been reduced. It is guaranteed that the data copied to the logical volume is in a consistent state as a file system, and the processing time can be shortened.

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

Outline Configuration of Data Mirroring System of Embodiment Example log structure Flow chart showing a write processing method from the host computer in the primary storage system Flow chart showing the procedure for mirroring data from the primary storage system to the secondary storage system

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Host computer, 102 ... Primary storage device system, 103 ... Secondary storage device system, 104 ... Network, 105 ... Control device, 106 ... Primary logical volume, 107 ... Log logical volume, 108 ... Secondary logical volume, 110 ... Primary logic Volume management means 111 ... Log logical volume management means 112 112 Mirroring means 113 113 Write order restriction detection means 120 120 Log structure 121 121 Write position information 122 122 Data length 123 123 Presence / absence of data synchronization option Information about 124, data

Claims (5)

A host computer, a primary storage system connected to the host computer and recording and holding data from the host computer, and a copy of data held by the primary storage system connected to the primary storage system. A secondary storage system for recording and holding, the primary storage system having a primary logical volume for recording and holding data from the host computer, and writing of data from the host computer to the primary logical volume And a control device that controls mirroring (copying) of data performed between the secondary storage system, and the secondary storage system records and holds a copy of the logical volume of the primary storage system Data mirror with storage device having A Gushisutemu,
The primary storage device system includes a storage device having a log logical volume used when mirroring data to the secondary storage device system;
The control device of the primary storage device system is:
Log logical volume management means for storing data sent from the host computer and information relating to write order restrictions in the log logical volume;
Write order restriction detection means for detecting information related to the write order restriction stored in the log logical volume;
According to the information detected by the write order restriction detecting means, the data stored in the log logical volume is changed according to the write request specifying the write order when there is a write order restriction, and the write order when there is no write order restriction. Mirroring control means for mirroring to the secondary storage system in response to an unspecified write request;
A data mirroring system comprising: The data mirroring system according to claim 1,
The log logical volume management means includes, in addition to the data and the information related to the write order restriction, write position information which is information indicating a write position to the logical volume and a data length which is the length of the data. A data mirroring system characterized by storing data in a logical volume. The data mirroring system according to claim 2,
A data mirroring system, wherein the data, the information related to the write order restriction, the write position information, and the data length are cyclically stored in the log logical volume as a structure. The data mirroring system according to any one of claims 1 to 3,
The data mirroring system characterized in that the information on the write order restriction is information on the presence or absence of a data synchronization option provided as a standard function of a protocol for connecting the host computer and the primary storage system. A host computer, a primary storage system connected to the host computer and recording and holding data from the host computer, and a copy of data held by the primary storage system connected to the primary storage system. A secondary storage system for recording and holding, the primary storage system having a primary logical volume for recording and holding data from the host computer, and writing of data from the host computer to the primary logical volume And a control device that controls mirroring (copying) of data performed between the secondary storage system, and the secondary storage system records and holds a copy of the logical volume of the primary storage system Data mirror with storage device having A data mirroring method in Gushisutemu,
The primary storage device system includes a storage device having a log logical volume used when mirroring data to the secondary storage device system;
The control device of the primary storage system includes log logical volume management means, write order restriction detection means, and mirroring control means,
The log logical volume management means storing in the log logical volume data sent from the host computer and information on write order restrictions;
The write order restriction detecting means detecting information related to a write order restriction stored in the log logical volume;
When the mirroring control means has the data stored in the log logical volume in accordance with the information detected by the write order restriction detection means, and there is a write order restriction, the write order is restricted by a write request specifying the write order. If not, mirroring to the secondary storage system by a write request that does not specify a write order; and
A data mirroring method comprising:

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