JP2008016028A - Distributed storage system with wide area replication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for evenly share process load of an I/O command by a whole storage array in a distributed storage system having a wide area memory allocation capability. <P>SOLUTION: The device and method with a virtual engine connectable to a remote device over a network for passing access commands between the remote device and a storage space. A plurality of intelligent storage elements (ISEs) 108-1, 1080-2 replicate data of a block size sufficient for processing an access command which is not yet processed from a first ISE to a second ISE independently of access commands being simultaneously passed between the virtual engine 200 and the first ISE. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates generally to the field of distributed data storage systems, and more particularly, but not exclusively, to an apparatus and method for replicating read-only data in a wide area within a distributed storage system.

  When the data transfer speed of the industry standard structure could not keep up with the data access speed of the 80386 processor manufactured by Intel (registered trademark), computer networking spread rapidly. By enhancing the data storage capacity in the network, the local area network (LAN) has evolved into a storage area network (SAN). By strengthening the equipment in the SAN and the associated data that this equipment processes, the user has the tremendous benefit of being able to process, for example, a memory that is a little larger than the storage device directly attached at a reasonable cost. Realized.

  Recent trends have shifted to a network-centric approach to controlling the data storage subsystem. That is, the system for controlling the storage function is also moved from the server to the network itself in the same way as the storage is strengthened. For example, host-based software delegates maintenance and management tasks to intelligent switches or dedicated network storage service platforms. Since the device-based method is used, software running in the host is not necessary, and this method operates in a computer provided as a node in the enterprise. In any case, the intelligent network scheme can centralize tasks such as storage allocation routines, backup routines, and fault tolerant design independent of the host.

  While moving the intelligence from the host to the network solves some of the problems, it does not solve the inherent problem that it is generally difficult to change the presentation of virtual memory to the host. For example, data stored under the direction of one controller may be more efficiently accessed in the storage space of another controller. In this case, the host or network must first copy the data to make it available to another controller. What is needed is intelligent data that voluntarily determines, allocates, manages, and protects each data storage capacity and presents that capacity to the network as virtual storage space to optimize I / O performance across the system. It is a storage subsystem. This virtual storage space can be arranged as a multiple storage volume. In a distributed computing environment, such intelligent storage elements are used to share the I / O command processing load as uniformly as possible across the storage array. The embodiment of the present invention relates to this method.

Embodiments of the present invention generally relate to a distributed storage system having global replication capability.
In one embodiment, a data storage system is provided that includes a virtual engine connectable to a remote device over a network for passing access commands between the remote device and a storage space. Multiple intelligent storage elements (ISEs) replicate data from the first ISE to the second ISE, independent of access commands being simultaneously passed between the virtual engine and the first ISE. .

In one embodiment, a method is provided for processing access commands between a virtual engine and an ISE and simultaneously replicating data from the ISE to another storage space.
In one embodiment, a data storage device is provided comprising a plurality of ISEs that can be individually addressed by a virtual engine and means for replicating data between intelligent storage elements.
These features and advantages which characterize the present invention will become apparent upon reading the following detailed description and upon reference to the associated drawings.

  FIG. 1 is an exemplary computer system 100 in which embodiments of the present invention are useful. One or more hosts 102 are networked to one or more network attached servers (NAS) 104 via a local area network (LAN) and / or a wide area network (WAN) 106. Preferably, LAN / WAN 106 uses an Internet Protocol (IP) networking infrastructure to communicate over the World Wide Web. The host 102 resides within the server 104 and accesses applications that routinely require data stored in one or more of a number of intelligent storage elements (ISEs) 108. For this reason, the SAN 110 connects the server 104 to the ISE 108 so that the stored data can be accessed. The ISE 108 comprises a block of data storage capacity 109 for storing data according to various selected communication protocols such as serial ATA and fiber channel, including enterprise class or desktop class storage media.

  FIG. 2 is a simplified diagram of the computer system 100 of FIG. Hosts 102 exchange information with each other and with a pair of ISEs 108 (shown as A and B, respectively) via a network or structure 110. Each ISE 108 includes a dual redundant controller 112 (shown as A1, A2 and B1, B2). Preferably, the controller 112 operates on a data storage capacity 109, which is a set of data storage devices characterized as a redundant array (RAID) of independent drives. Since the controller 112 and data storage capacity 109 preferably use a fault tolerant arrangement, the various controllers 112 use parallel redundant links and at least some of the user data stored in the system 100 is in the data storage capacity 109. At least one set is stored in a redundant format.

  In addition, A host computer 102 and A-ISE 108 are physically at the first site, B host computer 102 and B-ISE 108 are physically at the second site, and C host computer 102 is further at the first site. There may be 3 sites. However, this is just an example and not a limitation. All entities on a distributed computer system are connected by some type of computer network.

  FIG. 3 shows an ISE 108 constructed in accordance with an embodiment of the present invention. The shelf 114 defines a cavity for receiving and engaging the controller 112 to electrically connect with the central plate 116. The shelf 114 is supported in a cabinet (not shown). The shelf 114 receives and engages a pair of multiple disk assemblies (MDA) 118 on the same side of the central plate 116. On the opposite side of the center plate 116, a dual battery 122, a dual AC power supply 124, and a dual interface module 126, which are emergency power supplies, are connected. Preferably, in a dual component, one or both of the MDAs 118 operate simultaneously, so that backup protection can be provided if one component fails.

  FIG. 4 is an enlarged partial exploded isometric view of MDA 118 constructed in accordance with an embodiment of the present invention. The MDA 118 has an upper portion 130 and a lower portion 132, each supporting five data storage devices 128. The compartments 130, 132 align the data storage device 128 so that they can be connected to a common circuit board 134 having a connector 136 that engages the central board 116 (FIG. 3). Cover 138 shields against electromagnetic interference. This exemplary embodiment of MDA 118 is the subject of patent application 10 / 884,605, “Carrier Device and Method for a Multiple Disc Array”. This is assigned to the assignee of the present invention and is incorporated herein. Another exemplary embodiment of MDA is the subject of patent application 10 / 817,378 of the same title. This is also assigned to the assignee of the present invention and is incorporated herein. As will be described later, in another equivalent embodiment, the MDA 118 may be contained within a sealed container.

  FIG. 5 is an isometric view of an exemplary data storage device 128 in the form of a rotating media disk drive suitable for use with embodiments of the present invention. For purposes of the following description, a rotating spindle with a moving data storage medium is used, but another equivalent embodiment uses a non-rotating media device such as a solid state memory device. The data storage disk 140 is rotated by a motor 142 to present the data storage position of the disk 140 to a read / write head (simply called “head”) 143. The head 143 is supported at the tip of a rotary actuator 144 that moves the head 143 in the radial direction between the inner and outer tracks of the disk 140. The head 143 is electrically connected to the circuit board 145 by a flexible circuit 146. Circuit board 145 receives and sends control signals that control the function of data storage device 128. Connector 148 is electrically connected to circuit board 145 to connect data storage device 128 and circuit board 134 of MDA 118 (FIG. 4).

  FIG. 6 is a diagram of ISE 108 constructed in accordance with an embodiment of the present invention. The controller 112 operates in conjunction with an intelligent storage processor (ISP) 150 to manage data integrity reliability. ISP 150 may reside somewhere in controller 112, MDA 118, or elsewhere in ISE 108.

  Managed reliability aspects include creating a reliable data storage format such as a RAID scheme. For example, creating a relatively strong system for data storage by forming a system that selectively uses a selected one of a plurality of different RAID formats, and reduces the complexity of the software used to manage the MDA 118. Firmware algorithms can be optimized to reduce and recover relatively quickly from memory failure conditions. These aspects of this multiple RAID format system are described in patent application 10 / 817,264, “Storage Media Data Structure and Method”. This is assigned to the assignee of the present invention and is incorporated herein.

  Managed reliability may also include diagnostic and correction routine scheduling based on monitoring and using the system. Data recovery is performed by copying and reconstructing data. ISP 150 incorporates with MDA 118 to facilitate “self-healing” the entire data storage capacity without losing data. These aspects of managed reliability considered here are disclosed in patent application 10 / 817,617, “Managed Reliability Storage System and Method”. This is assigned to the assignee of the present invention and is incorporated herein. Other aspects of managed reliability include the speed of response to predictive failure indications for predetermined rules. This is disclosed, for example, in patent application 11 / 040,410, “Deterministic Predictive Recovering From a Predicted Failure in a Distributed Storage System”. . This is assigned to the assignee of the present invention and is incorporated herein.

  FIG. 7 is a diagram illustrating an ISP circuit board 152 in which a pair of redundant ISPs 150 reside. The ISP 150 interfaces the data storage capacity 109 with the SAN structure 110. Each ISP 150 may manage various storage services such as path selection, volume management, and data movement and replication. ISP 150 divides ISP circuit board 152 into two ISP subsystems 154 and 156 that are coupled by bus 158. The ISP subsystem 154 includes an ISP 150 indicated by “B”. This is connected to SAN structure 110 by link 160 and to data storage capacity 109 by link 162. The ISP subsystem 154 also includes a policy processor 164 that executes a real-time operating system. ISP 150 and policy processor 164 communicate over bus 166 and both communicate with memory 168.

  FIG. 8 is a diagram of an exemplary ISP subsystem 154 constructed in accordance with an embodiment of the present invention. ISP 150 includes a number of function controllers (170-180) that communicate with list managers 182, 184 via a cross point switch (CPS) 186 message crossbar. In this way, the function controllers (170-180) generate CPS messages according to predetermined conditions, respectively, and send these messages to the list managers 182 and 184 through the CPS 186 to access the memory modules and perform the activities of the ISP 150. You may wake up. Similarly, responses from list managers 182, 184 may be sent via CPS 186 to any of the function controllers (170-180). The arrangement of FIG. 8 and the associated description are examples and do not limit the possible embodiments of the present invention.

  Policy processor 164 may be programmed to perform desired operations via ISP 150. For example, policy processor 164 may communicate with list managers 182, 184 (ie, send and receive messages) via CPS 186. The response to the policy processor 164 may serve as an interrupt that signals the reading of the memory 168 register.

  FIG. 9 is a diagram illustrating the superior flexibility of the ISE 108 that communicates with the host 102 in any of a plurality of preselected communication protocols (such as FC, iSCSI, or SAS) by the intelligent controller 112. The ISE 108 may be programmed to check the fetch level of the host command and map the virtual storage volume to the physical storage 109 associated with the command accordingly.

  For the purposes of the present invention, the term “virtual storage volume” means a logical entity that generally corresponds to the logical retrieval of physical storage. A “virtual storage volume” is, for example, as if it were a record in a continuously addressed address block or count-key-data structure in a fixed block structure (logical May include the entity being handled). A virtual storage volume may physically reside on more than one storage element.

FIG. 10 is a diagram showing the types of data management services that the ISE 108 may perform independently of any host 102. For example, RAID management is controlled locally for fault-tolerant data integrity, and data striping is performed in the desired number of data storage devices 128 ₁ , 128 ₂ , 128 ₃ ,. . . , 128 _n . The virtualization service may be controlled locally to allocate or deallocate memory capacity to logical entities. Application routines such as the managed reliability scheme described above and data replication between logical volumes within the same ISE 108 may be controlled locally as well. For purposes of this description and claims, the terms “move” or “move” refer to erasing the original data as part of the move completion by moving the data from the source to the destination. This is the opposite of “duplicating” or “duplicating” data. In the case of copying, data is copied from the source to the destination. However, it will have a different name at the destination. In the present invention, duplication is performed to efficiently make a read-only copy of the data other than where data integrity is maintained.

  FIG. 11 shows data that the virtual engine 200 communicates with the remote host device 102 via the SAN 106 to pass an access command (I / O command) between the host device 102 and a selected one of the plurality of ISEs 108. 1 illustrates an embodiment of a storage system 100. Each ISE 108 has two ports 202, 204 and 206, 208 that the virtual engine 200 can uniquely address to pass access commands. In order to facilitate data replication without creating a data transfer bottleneck, the following describes how this embodiment replicates data between ISEs 108 independently and simultaneously with host access command processing. In addition, by changing the data transfer speed when data is replicated, the influence on the application performance of the system 100 can be optimized.

  In ISE 108-1, the ISP 150 creates a logical volume 210 for the physical data pack 212 of the data storage device 128. For illustration purposes, assume that 40% of the storage capacity of the data pack 212 is allocated to the logical disk 214 in the logical volume 210. Also for purposes of explanation, assume that data pack 212 and all other data packs below include eight data storage devices 128 and two spare data storage devices 128 for data storage. Further, as can be seen from FIG. 11, in ISE 108-1, the other data pack 216 allocates 93% to logical disk 218, and in ISE 108-2, data packs 220 and 222 are 30% to logical disks 224 and 226, respectively. And 40%.

  The virtual engine 200 creates a logical volume 224 from the logical disk 214 and creates a logical disk 226 in response to a request for storage space from the host and maps it to the host 102.

  Under certain predefined conditions, it is better to process the access command with a controller other than the unit master controller for a specific LUN (logical unit number). Unlike mirroring, which copies all data in a predetermined array for redundancy, this embodiment provides a narrow read of data under conditions that are likely to process access commands with relatively high performance. Direct the dedicated copy to the target storage space.

  As an illustrative example, it is assumed that an access command for data in the LUN is received, but the controller A in the ISE 108-1 is currently streaming sequential data access commands. Rather than interrupting command streaming or waiting for streaming to process this parallel command, controller A does not read all or part of the read-only copy of the LUN as shown in FIG. You may replicate to different storage spaces.

  In general, the unit master controller can identify another storage space with relatively high processing power over the system in order to process outstanding access commands. This separate storage space may be internal to the unit master controller, externally to another controller in the same ISE 108, or globally to another ISE 108. In any case, the comparative throughput may be determined for any number of desirable parameters. For example, the availability of resources for processing access commands may be compared. In another example, a quality or quantity comparison of I / O command queue depth may be used, or a controlled reliability factor comparison may be used.

As will be appreciated, this embodiment contemplates replicating only a snapshot copy of the data to another storage space in order to process a particular access command. Data integrity is maintained in the source LUN.
It will also be appreciated that the exemplary embodiment of FIG. 12 illustrates duplicating the entire LUN in another storage space. Or, if only a portion of the LUN is needed to process an outstanding access command, only that portion may be duplicated. Similarly, all or only part of a LUN, or all or only part of a sub LUN, may be copied with each assigned sub LUN. In general, replicated data should be only what is needed to process outstanding access commands.

  FIG. 13 is a flow diagram of example steps for executing a global replication method 250 in accordance with an embodiment of the present invention. The method is performed at block 252 in the normal I / O processing mode of the system. Block 254 determines whether the last I / O command has been processed. If yes, the method ends.

  Block 256 determines if there are any conditions for which it is better to consider global replication. For example, if you are currently sharing a load relatively evenly among multiple ISEs and are likely to end up using the unit controller's own storage space, whenever you store an access command Those who do not decide to find the optimal storage space will be able to save valuable resources. However, as those skilled in the art will recognize, there may be other conditions where it is better to perform the global replication mode. For example, when the managed reliability is related to a specific ISE 108, the controller is sequentially processing data, or the specific ISE 108 is currently idle and has a relatively large resource base available. However, it is not limited to these.

  If the determination at block 256 is yes, block 258 determines whether there is a global replication candidate access command. In this case as well, it is preferable to determine a threshold value for examining what is likely to degrade the system performance instead of examining each access command. For example, the situation described above where the unit master controller is dependent on sequential data processing is likely to be a candidate for processing unprocessed parallel access commands. Another example is when the unit master controller is in a short stroking routine and the outstanding access command needs to be removed from the routine.

  If the determination at block 258 is yes, block 260 determines the optimal storage space for processing the outstanding access command. As stated above, this decision is typically made as to which storage space has a relatively high processing capacity to process an outstanding access command. “Relatively high processing power” may be determined in terms of resource availability, outstanding I / O command queue depth, and managed reliability, but is not limited thereto. The target storage space may be internal, external or global with respect to the unit master controller.

  Finally, at block 262, the unit master controller replicates the read-only copy to the storage space determined at block 260. As explained above, the size of the replicated data block is preferably as large as necessary to process an outstanding access command. For example, the replicated data may include all or only part of a LUN, all or part of a LUN and its respective sub LUNs, or all or only part of a sub LUN.

  As those skilled in the art will appreciate, this method is different from data mirroring, where the data is stored in advance and a complete copy of the original data is stored. This embodiment replicates data into the second ISE 108 to process the first access command, and then replicates the same data into another third ISE 108 to process the second access command. You can do it.

  Finally, FIG. 14 is a view similar to FIG. 4, but a plurality of data storage devices 128 and a circuit board 134 are housed in a sealed container formed by a base 190 and a sealed cover 192 attached thereto. Sealing and engaging the data storage device 128 that forms the MDA 118A has various advantages, such as that the placement of the data storage device 128 does not change from a preselected optimal placement. Also, if the number, size, and type of data storage devices 128 can be clearly defined, such an arrangement allows the MDA 118A producer to adjust the system for optimum performance.

  Sealing the MDA 118A also maximizes the reliability and fault tolerance of a group of internal storage media, while requiring little service as long as the MDA 118A has a lifetime. This is done by optimizing a multi-spindle drive. Design optimization reduces costs, improves performance, improves reliability, and generally extends the life of data in MDA 118A. Furthermore, the design of the MDA 118A itself eliminates rotational vibration, and an environment with high cooling efficiency can be obtained. This is the subject of pending US patent application 11 / 145,404, “Storage Array with Enhanced RVI”. This is assigned to the assignee of the present application. Thereby, an internal storage medium can be manufactured at a low cost without reducing the reliability, performance, or capacity of the MDA 118. Sealing the MDA 118A in this way eliminates a single point of failure and eliminates rotational vibration and almost complete cooling efficiency. As a result, the MDA 118A can be designed to optimize the disk medium characteristics, thereby reducing costs and at the same time improving reliability and performance.

  In summary, a built-in ISE for a distributed storage system including a plurality of rotatable spindles is provided. Each spindle supports a storage medium in proximity to the independently moving actuator, which stores and retrieves data from and to the storage medium. The ISE further includes an ISP that maps virtual storage volumes to multiple media for use by remote devices in a distributed storage system.

  In some embodiments, the ISE has a plurality of spindles and media housed in a common sealed housing. Preferably, the ISP allocates memory in the virtual storage volume for storing data in a manner that is resistant to failure, such as a RAID scheme. In addition, during the data storage process, the ISP can implement a managed reliability scheme, such as voluntarily initiating a deterministic preventive recovery step upon detecting a predicted storage failure. Preferably, the ISE is formed of a plurality of data storage devices each having a disk stack formed from two or more disk data storage media.

  In another embodiment, the ISE includes a distributed storage comprising a plurality of built-in discrete data storage devices and an ISP that communicates with the data storage devices to retrieve commands received from remote devices and associate memory associated therewith. Used in the system. Preferably, the ISP maps a virtual storage volume to a plurality of data storage devices for use by one or more remote devices of the distributed storage system. As before, a plurality of data storage devices and media may be contained in a common sealed housing. Preferably, the ISP allocates memory in the virtual storage volume to store the data in a manner that resists failures, such as a RAID scheme. In addition, the ISP spontaneously initiates a deterministic preventive recovery step within the data storage device upon detecting a predicted storage failure.

  In another embodiment, a distributed storage system is provided that includes a host, a rear storage subsystem that communicates with the host over a network, and means for virtualizing built-in storage capacity regardless of the host.

  The means for virtualizing may feature a plurality of discrete and individually accessible data storage units. The means for virtualizing may map virtual blocks of storage capacity associated with a plurality of data storage units. The means for virtualizing may be characterized by enclosing a plurality of data storage units and associated controls. The means for virtualizing is not limited, but may be characterized in that data is stored in a method that can withstand failures such as a RAID system. The means for virtualizing may be characterized by voluntarily initiating a deterministic preventive recovery step upon detecting a predicted memory failure. The means for virtualizing may feature multiple spindle data storage arrays.

  For the purposes here, the term “means to virtualize” does not explicitly consider previously attempted solutions, including system intelligence to map the data storage space somewhere other than the respective data storage subsystem. . For example, “virtualizing means” does not consider using a storage manager to control the functions of the data storage subsystem, nor does it consider placing a manager or switch in the SAN structure or in the host.

  Alternatively, this embodiment features a data storage system that includes a virtual engine connected to the remote device over a network for passing access commands between the remote device and the storage space. The data storage system further includes a plurality of intelligent storage elements (ISEs) that the virtual engine can uniquely address to pass access commands. Regardless of passing an access command between the virtual engine and the first ISE, the ISE simultaneously transfers data from the first ISE to the second ISE.

  In one embodiment, each ISE has a plurality of rotatable spindles, each spindle supporting a storage medium proximate to an independently moving actuator, and the actuator stores data to and from the storage medium. Search. Multiple spindles and media may be contained in a common sealed housing.

  Each ISE has a processor for mapping and managing virtual storage volumes to a plurality of media. Each ISE processor preferably allocates memory within the virtual storage capacity to store data in a manner that tolerates failures, such as a selected one of a plurality of different independent drive redundant array (RAID) schemes.

  Each ISE processor may voluntarily perform a deterministic preventive recovery step upon detecting a memory failure. When doing this, each ISE processor may allocate a second virtual storage capacity upon detecting a memory failure. In some embodiments, each ISE processor allocates a second virtual storage capacity in a different ISE.

  This embodiment is further characterized as a method for processing access commands between a virtual engine and an intelligent storage element and simultaneously transferring data from the intelligent storage element to another storage space.

  The processing step may be characterized in that the intelligent storage element maps and manages the virtual storage volume to the built-in physical storage. Preferably the transferring step is characterized in that upon detecting a memory failure, the intelligent storage element spontaneously initiates a deterministic preventive recovery step.

  The transferring step may be characterized in that the intelligent storage element allocates a second virtual storage volume upon detecting a storage failure. In one embodiment, the transferring step is characterized in that the virtual engine allocates a second virtual storage volume for physical storage that has specified a different address in the processing step. For example, the transferring step may be characterized by allocating a second virtual storage volume within the intelligent storage element. Alternatively, the transferring step may be characterized by allocating the second virtual storage volume outside the intelligent storage element. That is, the transferring step is characterized by allocating a second virtual storage volume in the second intelligent storage element.

  The processing step may be characterized by allocating memory and storing the data in a manner that resists failure. The processing step may also be characterized by moving the data transfer element and the storage medium relative to each other while transferring the data within a common sealed housing.

  Alternatively, this embodiment features a data storage system having a plurality of intelligent storage elements that can be individually addressed by a virtual engine and means for moving data between intelligent storage elements. For the purposes of this description and claims, the term “means of transferring” with respect to the structures described herein and the like is used to refer to data without interrupting normal I / O command processing associated with host access commands. It means copying from one logical unit to another.

  Alternatively, this embodiment features a data storage system comprising a virtual engine that is connectable to a remote device over a network for passing access commands between the remote device and the storage space. The plurality of ISEs replicate data from the first ISE to the second ISE independently of the access commands being simultaneously passed between the virtual engine and the first ISE. Each ISE has a plurality of rotatable spindles, each spindle supporting a storage medium proximate to an independently moving actuator, which stores and retrieves data from and to the storage medium.

The replicated data typically produces a read-only copy of a block size sufficient to process an outstanding access command. That is, the ISE may replicate all or part of a LUN, all or part of a LUN and its respective sub-LUNs, or all or part of a sub-LUN.
The first ISE (unit master) identifies the second ISE among the plurality of ISEs as having a relatively high processing capability for processing access commands associated with replicated data. The determination of processing power may be made with respect to resource availability, outstanding I / O command queue depth, and managed reliability.

  Alternatively, this embodiment features a method of processing access commands between the virtual engine and the ISE and simultaneously replicating data from the ISE to another storage space. In general, this method considers replicating only the data necessary to process an outstanding access command. In one embodiment, the replicating step is characterized by replicating only a portion of the LUN in the first ISE to a read-only copy in the second ISE. Alternatively, the replicating step is characterized by replicating all LUNs in the first ISE to a read-only copy in the second ISE. Alternatively, the replicating step is characterized by replicating the LUN in the first ISE and its respective sub-LUN to a read-only copy in the second ISE. Alternatively, the replicating step is characterized by replicating only the sub LUN in the first ISE to a read-only copy in the second ISE.

  The processing step assumes that the first ISE of the plurality of ISEs selects the second ISE from the plurality of ISEs as having relatively high processing power to process access commands associated with the replicated data. It is characterized by identifying. The determination of processing power may be made with respect to resource availability, outstanding I / O command queue depth, and managed reliability. Once the processing power is determined, replication is performed internally, externally, or globally with respect to the first ISE.

  The method is further characterized by selecting a rate at which data is transferred with respect to the desired performance of the target storage space. In general, replication makes a read-only copy directed to any of a plurality of target storage spaces. For example, the method replicates data from a first ISE to a second ISE to process a first outstanding access command, then replicates the data for the same data to a second ISE to Process the access command.

  Alternatively, this embodiment features a data storage system having a plurality of ISEs that can be individually addressed by a virtual engine and means for replicating data between intelligent storage elements. For the purposes of this description and in the meaning of the claims, the term “means to replicate” means that the unit master controller replicates data to evaluate system-wide performance parameters and process outstanding access commands accordingly. Requires the structure disclosed herein.

  As will be appreciated, while the foregoing description has set forth many features and advantages of various embodiments of the invention, along with details of the structure and function of the various embodiments of the invention, this detailed description Are merely exemplary, and modifications may be made in details, particularly within the broad general meaning of the terms expressing the claims, regarding the structure and arrangement of portions within the principles of the invention. For example, certain elements may be varied according to a particular processing environment without departing from the spirit and scope of the present invention.

  Further, although the embodiments described herein relate to data storage arrays, as those skilled in the art will recognize, the claimed subject matter is not so limited and does not depart from the spirit and scope of the invention. Various other processing systems may be used as long as they are.

  This application is a continuation-in-part of US Application No. 11 / 145,403, filed June 3, 2005 and assigned to the assignee of the present application.

FIG. 1 is a diagram of a computer system in which embodiments of the present invention are useful. FIG. 2 is a simplified diagram of the computer system of FIG. FIG. 3 is an exploded isometric view of an intelligent storage element constructed in accordance with an embodiment of the present invention. FIG. 4 is a partially exploded isometric view of the multiple disk array of intelligent storage elements of FIG. FIG. 5 is an exemplary data storage device used in the multiple disk array of FIG. FIG. 6 is a functional block diagram of the intelligent storage element of FIG. FIG. 7 is a functional block diagram of the intelligent storage processor circuit board of the intelligent storage element of FIG. FIG. 8 is a functional block diagram of the intelligent storage processor of the intelligent storage element of FIG. FIG. 9 is a functional block diagram representation of command retrieval and associated memory mapping services performed by the intelligent storage element of FIG. FIG. 10 is a functional block diagram of another exemplary data service performed by the intelligent storage element of FIG. FIG. 11 is a diagram showing a wide area replication method according to an embodiment of the present invention. FIG. 12 is a diagram showing a wide-area replication method according to the embodiment of the present invention. FIG. 13 is a flowchart of steps for executing the global replication method according to the embodiment of the present invention. FIG. 14 is a view similar to FIG. 3 but showing the data storage device and circuit board housed in a sealed container.

Explanation of symbols

102 Remote device (host)
108 Intelligent Storage Element (ISE)
109 Storage space 200 Virtual engine

Claims (21)

A data storage system,
A virtual engine connectable to the remote device over a network for passing access commands between the remote device and the storage space;
A plurality of intelligent storage elements (ISEs) that transfer data from the first ISE to the second independent of the access command being passed between the virtual engine and the first ISE at the same time. The ISE to be replicated to the ISE,
The data storage system comprising:   2. Each ISE comprises a plurality of rotatable spindles, each spindle supporting a storage medium proximate to an independently moving actuator, said actuator storing and retrieving data from and to the storage medium. The data storage system described.   The data storage system of claim 2, wherein the ISE copies only a portion of a logical unit number (LUN) in the first ISE to a read-only copy in the second ISE.   The data storage system of claim 2, wherein the ISE copies all LUNs in the first ISE to a read-only copy in the second ISE.   The data storage system of claim 2, wherein the ISE copies a LUN in the first ISE and its corresponding sub-LUN to a read-only copy in the second ISE.   The data storage system of claim 2, wherein the ISE copies only sub-LUNs in the first ISE to a read-only copy in the second ISE.   The first ISE identifies the second ISE from a plurality of previous ISEs as having a relatively high processing capability to process an access command associated with the replicated data. The data storage system described.   8. The ability to process is determined with respect to a parameter in a set of parameters consisting of resource availability, outstanding I / O command queue depth, and managed reliability. Data storage system.   Processing an access command between the virtual engine and the ISE and simultaneously replicating data from the ISE to another storage space.   The method of claim 9, wherein the duplicating step duplicates only a portion of the LUN in the first ISE to a read-only copy in the second ISE.   The method of claim 9, wherein the duplicating step duplicates all LUNs in the first ISE to a read-only copy in the second ISE.   The method of claim 9, wherein the duplicating step duplicates a LUN in a first ISE and its respective sub-LUN to a read-only copy in a second ISE.   The method of claim 9, wherein the duplicating step duplicates only the sub-LUNs in the first ISE to a read-only copy in the second ISE.   The step of processing identifies a second ISE of a plurality of ISEs that identifies the second ISE from a plurality of ISEs as having relatively high processing power to process an access command associated with the replicated data. 10. A method according to claim 9, characterized by one ISE.   15. The ability to process is determined with respect to a parameter from a set of parameters consisting of resource availability, outstanding I / O command queue depth, and managed reliability. Method.   The method of claim 9, wherein the processing step replicates data within the ISE.   10. The method of claim 9, wherein the processing step replicates data outside the ISE.   The method of claim 9, wherein the processing step replicates data in a second ISE.   The method of claim 9, wherein the processing step selects a rate at which data is transferred with respect to a desired performance of the target storage space.   The method of claim 18, wherein the step of processing replicates data in a third ISE that is different from the second ISE. A data storage system,
Multiple ISEs that the virtual engine can address individually;
Means for replicating data between intelligent storage elements;
A data storage system comprising:

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