US20150134929A1 - Load Balancing Logical Units in an Active/Passive Storage System - Google Patents

Abstract

An approach is provided in which a storage system includes a first storage controller, a second storage controller, and multiple logical units. The storage system determines that a controller traffic load ratio between the first storage controller and the second storage controller has reached a threshold. In turn, the storage system selects one of the logical units and changes a preferred controller ownership of the selected logical unit from the first storage controller to the second storage controller to balance the controller traffic load ratio.

Description

BACKGROUND
• The present disclosure relates to load balancing logical units in an active/passive storage system. More particularly, the present disclosure relates to dynamically updating preferred controller ownership of logical units to balance data traffic loads passing through the storage controllers.
• A storage area network (SAN) is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage resources (e.g., disk arrays, tape libraries, optical jukeboxes, etc.) accessible to servers such that the resources appear as locally attached devices to the operating system.
• A SAN typically includes file systems, which are logical storage abstraction mappings to the physical storage resources (storage virtualization). In a block-based storage environment, a single block of information is addressed using a logical unit (LUN) identifier and an offset within that LUN—known as a logical block addressing (LBA). The LUN identifier identifies a logical unit from multiple LUNs and is essential for managing block storage arrays of a storage area network (SAN). A typical LUN may be used with any storage resource that supports read/write processes.
• A SAN may include several storage controllers that interface host systems to the LUNs. Multi-controller storage systems may be configured in an active/active configuration or an active/passive configuration. In an active/passive configuration, the SAN specifies a “preferred controller” for each logical unit. As such, a host operating system uses the preferred controller to access a particular logical unit as long as the controller is available. When the preferred controller is unavailable (e.g., network connection issue, device issue, etc.), the host operating system accesses the SAN's other storage controller.
BRIEF SUMMARY
• According to one embodiment of the present disclosure, an approach is provided in which a storage system includes a first storage controller, a second storage controller, and multiple logical units. The storage system detects that a controller traffic load ratio between the first storage controller and the second storage controller has reached a threshold. The storage system, in turn, selects one of the logical units and changes a preferred controller ownership of the selected logical unit from the first storage controller to the second storage controller to balance the controller traffic load ratio.
• The foregoing is a summary and thus contains, by necessity, simplifications, generalizations, and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the present disclosure, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth below.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
• The present disclosure may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings, wherein:
• FIG. 1 is a diagram showing an example of a storage system dynamically adjusting preferred controller logical unit ownership based upon logical unit traffic loads at the storage controllers;
• FIG. 2A is a diagram showing an example of an ownership configuration user interface on which an administrator selects an ownership configuration;
• FIG. 2B shows an example of a logical unit ownership table managed bystorage system100;
• FIGS. 3A and 3B are diagrams showing an example of a storage system changing preferred controller ownership when a controller traffic load ratio reaches an auto-balance threshold;
• FIG. 4 is a diagram showing one example of a host system sending an inquiry to a storage system prior to accessing a logical unit through a storage controller;
• FIG. 5 is a flowchart showing one example of steps taken by a storage system to manage logical unit data traffic load balancing between storage controllers;
• FIG. 6 is a flowchart showing one example of steps taken by a host system to send/receive data to/from logical units through selected storage controllers;
• FIG. 7 is diagram showing an example of a graphical representation a storage system maintaining a balanced traffic load between two storage controllers by dynamically adjusting preferred controller ownership of logical units within the storage system;
• FIG. 8 is a block diagram of a data processing system in which the methods described herein can be implemented; and
• FIG. 9 provides an extension of the information handling system environment shown inFIG. 8 to illustrate that the methods described herein can be performed on a wide variety of information handling systems which operate in a networked environment.
DETAILED DESCRIPTION
• The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
• The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.
• As will be appreciated by one skilled in the art, aspects of the present disclosure may be embodied as a system, method or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.
• Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
• A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
• Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
• Computer program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
• Aspects of the present disclosure are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
• These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
• The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
• The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
• The following detailed description will generally follow the summary of the disclosure, as set forth above, further explaining and expanding the definitions of the various aspects and embodiments of the disclosure as necessary.
• FIG. 1 is a diagram showing an example of a storage system dynamically adjusting preferred controller logical unit ownership based upon logical unit traffic loads at the storage controllers. Storage system100 (e.g., a storage area network) includeslogical units120,125, and130, which provide a logical storage abstraction of physical storages170-190 tohosts140 and150. In one embodiment, physical storages170-190 are aggregated into storage pools from which the logical storage is created. Such storage virtualization helps achieve location independence by abstracting the physical location of the data. As such,system100 presents tohosts140 and150 a logical space for data storage and handles the process of mapping the data to the actual physical location (physical storage170-190).
• Storage controllers105 and110, in one embodiment, manage data traffic between logical units120-130 and hosts140-150 in an active/passive configuration. Those skilled in the art understand that, in an active/passive configuration, each logical unit has an assigned preferred controller and an assigned current controller. A particular logical unit's preferred controller is the controller a host should use when the host unit accesses the logical unit. A logical unit's current controller is the controller temporarily utilized by a host when the host is unable to access the logical unit via the preferred controller (e.g., network connection issues, controller issues, etc.).
• Storage system100 may initially configure preferred controller logical unit ownership according to default parameters, such as assigning half of the logical units tostorage controller105 and the other half of the logical units to thestorage controller110.Storage system100 uses logical unit (LUN) ownership table115 to track logical unit controller ownership information via preferred controller identifiers and current controller identifiers (seeFIG. 2B and corresponding text for further details).FIG. 1 shows thatstorage controller 1105 is the designated preferred controller forlogical unit A120 and logical unit B125 (solid lines), andstorage controller 2110 is the designated preferred controller forlogical unit C130. The dashed lines shown inFIG. 1 represent storage system's active/passive configuration in that preferred controller ownership may be dynamically updated to balance data traffic loads betweenstorage controller 1105 andstorage controller 2110.
• Whenhost140 receives a request from an application to access data,host140 identifies a corresponding logical unit and sends an inquiry tostorage system100 to receive information (stored in LUN ownership table115) as to the logical unit's preferred controller. In turn, host140 stores the preferred controller information in local table145 and begins accessing the logical unit through the preferred controller. For example, host140 may receive a request to access data onlogical unit A120 and, in this example, determines thatstorage controller 1105 is the preferred controller (fromstorage system100's response, seeFIG. 4 and corresponding text for further details).
• As network activity increases,storage system100 monitors the “controller traffic load ratio” between logical unit data traffic passing throughstorage controller 1105 andstorage controller 2110. Whenstorage system100 detects an unbalanced amount of traffic passing through one storage controller compared to the other storage controller,storage system100 dynamically changes the preferred controller ownership of one or more of the logical units via logical unit ownership table115, such as changing the preferred controller oflogical unit B125 fromstorage controller 1105 tostorage controller 2110 (seeFIGS. 3A,3B, and corresponding text for further details).
• In turn, whenhost140 orhost150 sends an inquiry tostorage system100 that inquires aboutlogical unit B125's preferred controller,storage system100 sends a response that identifiesstorage controller 2110 as the new preferred controller. As such,host140 and host150 update their local tables145 and155, respectively, and accesslogical unit B125 throughstorage controller110 to balance the data traffic passing through the two different storage controllers.
• FIG. 2A is a diagram showing an example of an ownership configuration user interface on which an administrator selects an ownership configuration. In one embodiment,storage system100displays window200 to an administrator, which allows the administrator to select between a dynamic ownership configuration (automatically adjust preferred controller logical unit ownership), or a static ownership configuration (fixed preferred controller logical unit ownership).
• Window200 shows that an administration selectsbox210 to configurestorage system100 in a dynamic ownership configuration. In addition, the administrator enters an auto-balance threshold inbox215, which triggersstorage system100 to adjust preferred controller ownership when the controller traffic load ratio reaches the entered auto-balance threshold. The example inFIG. 2A shows a value of +/−10%, which indicates thatstorage controller100 adjusts the preferred controller ownership when the data traffic passing through one storage controller is +/−10% more/less than the data traffic passing through the other storage controller (seeFIG. 7 and corresponding text for further details).
• The administrator selectsbox220 to configurestorage system100 in a static ownership configuration. When the administrator selectsbox220, the administrator also enters logical unit identifiers inboxes225 and storage controller identifiers inbox230, which set the storage controllers as the preferred controllers of the corresponding logical units. As those skilled in the art can appreciate, althoughstorage system100 may change the current controller identifiers of logical units in the static ownership configuration (based on network connection issues, device issues, etc.),storage system100 does not changes the preferred controller identifiers in the static ownership configuration.
• FIG. 2B shows an example of a logical unit ownership table managed bystorage system100. Logical unit ownership table115 includes logical unit identifiers (column240), preferred controller identifiers (column250), and current controller identifiers (column260). As can be seen,storage controller 1105 is the preferred controller for logical unit A, whereasstorage controller 2110 is the preferred controller for logical units B and C. Logical unit ownership table115 also shows that logical unit B's current controller isstorage controller 1105. This may be due to a host system not being able to access logical unit B throughstorage controller 2110, in which case the host system sends a notice tostorage system100, which changes the current controller fromstorage controller 2110 (matching the preferred controller) tostorage controller 1105 (seeFIG. 6 and corresponding text for further details).
• FIGS. 3A and 3B are diagrams showing an example of a storage system changing preferred controller ownership when a controller traffic load ratio reaches an auto-balance threshold. Referring toFIG. 3A,storage system100's ownership table115 shows thatstorage controller 1105 is the preferred controller forlogical unit A120 andlogical unit B125, andstorage controller 2110 is the preferred controller forlogical unit C130. During operation,storage system100 monitors the relative amount of data traffic throughstorage controller 1105 andstorage controller 2110, which is referred to herein as the controller traffic load ratio. When the amount of data traffic throughstorage controller 1105 becomes disproportionate to the amount of data traffic throughstorage controller 2110 (e.g., reaches an auto-balance threshold),storage system100 changes preferred controller ownership of one or more of the logical units to balance the data traffic through the storage controllers (seeFIG. 3B and corresponding text for further details).
• FIG. 3B shows that, compared toFIG. 3A,storage system100 changedlogical unit B125's preferred controller ownership and current controller fromstorage controller 1105 tostorage controller 2110 (shown in logical unit ownership table115). As such, when a host system sends an ownership inquiry tostorage system110,storage system110 sends the updated preferred controller ownership/current controller information and, in turn, the inquiring host accesseslogical unit B125 throughstorage controller 2110.
• FIG. 4 is a diagram showing one example of a host system sending an inquiry to a storage system prior to accessing a logical unit through a storage controller.Host140 sendsinquiry400 tostorage system100, which inquires about the ownership of a particular logical unit (identified by LUN ID in inquiry400).Storage system100, in turn, access LUN ownership table115 and retrieves the preferred controller ID and the current controller ID corresponding to the logical unit identified ininquiry400.Storage system100 sends ownership response410 back tohost140, which includes the LUN ID, the preferred controller ID, and the current controller ID. Host140, in turn, updates local table145 with the ownership information and proceeds to access the logical unit via the identified preferred storage controller (seeFIG. 6 and corresponding text for further details).
• FIG. 5 is a flowchart showing one example of steps taken by a storage system to manage logical unit data traffic load balancing between storage controllers. Processing commences at500, whereupon the storage system provides a configuration user interface (e.g.,window200 shown inFIG. 2A) to a user and receives an ownership configuration selection from the user (505). A determination is made as to whether the ownership configuration selection is a static configuration selection or a dynamic configuration selection (decision510). If the user selects a static ownership configuration,decision510 branches to the “static” branch, whereupon the storage system populates logical unit ownership table115 with static ownership preferences included in the user's response and preferred controller ownership management ends at520. As those skilled in the art can appreciate,storage system100 may update the current controller information in a static ownership configuration, but the preferred controller ownership remains fixed.
• On the other hand, if the user selects a dynamic ownership configuration,decision510 branches to the “dynamic” branch, whereupon the storage system populates logical unit ownership table115 with default ownership preferences at525. For example, the storage system may assign the first half of logical units (e.g., 1-3) to the first storage controller and assign the second half of logical units (e.g., 4-6) to the second storage controller.
• At530, the storage system monitors input/output loads of the storage controllers (data traffic load) and computes a controller traffic load ratio. In one embodiment, the storage system may use a total number of bytes transferred within a given time period (e.g., within the last minute). In this embodiment, ifcontroller 1 owns LUN A and LUN B, andcontroller 2 owns LUN C, then the controller traffic load ratio is “traffic on LUN A+traffic on LUN B:traffic on LUN C”.
• A determination is made as to whether the controller traffic load ratio exceeds an auto-balance threshold (decision540). In one embodiment, the user provides the auto-balance threshold (e.g., +/−10%), such asthreshold215 shown inFIG. 2A. If the controller traffic load ratio does not exceed the auto-balance threshold,decision540 branches to the “No” branch, which loops back to continue to monitor the data traffic loads on each storage controller.
• On the other hand, if the controller traffic load ratio reaches the auto-balance threshold,decision540 branches to the “Yes” branch, whereupon the storage system updates the preferred controller/current controller ownership of one or more logical units accordingly to balance the traffic load between controllers. For example, the storage system may partition the LUNs into different groups and identify a particular partition that provides the optimum controller traffic load ratio (e.g., closest to a value of “1”).
• A determination is made as to whether to continuing monitoring the data traffic loads on the storage controllers (decision560). If the storage system should continue to monitor data traffic loads,decision560 branches to the “Yes” branch, which loops back to dynamically adjust preferred controller ownership based upon load conditions. On the other hand, if the storage controller should stop monitoring load conditions,decision560 branches to the “No” branch, whereupon processing ends at570.
• FIG. 6 is a flowchart showing one example of steps taken by a host system to send/receive data to/from logical units through selected storage controllers. Processing commences at600, whereupon the host system receives a request fromapplication605 to send/receive data at610.
• The host system identifies the logical unit associated with the request (via fromapplication605 or file system) and accesses local table145 to identify the current controller of the identified logical unit (620). Local table145 includes ownership information based upon the host system's last interaction withstorage system100. The host system sends a request to the identified current controller to send/retrieve data to/from a particular LUN (630).
• A determination is made as to whether the host system received a response from storage system100 (decision640). When a connection between the host system andstorage system100 is functioning correctly,storage system100 receives the request and provides either a valid response or an error response to the host system that indicates the controller, which the host thought was the current controller, is actually not the current controller of the requested LUN. However, when the connection is not functioning properly (transmit path down, receive path down, storage controller non-functional, etc.), the host system does not receive a response.
• If the host system receives a valid response,decision640 branches to the “Valid” branch whereupon the host system sends/receives data to/from the LUN through the current controller (660). On the other hand, if the host received an error message,decision640 branches to the “Error” branch whereupon the host changes the current controller of the LUN in local table145 (e.g.,controller 1 to controller2) at655, and sends/receives data to/from the LUN through the new current controller (660).
• However, if the host does not receive a response fromstorage system100,decision640 branches to the “None” branch, whereupon the host changes the current controller of the LUN in local table145 (e.g.,controller 1 to controller 2) at650, and sends a notice tostorage system100 of the change in current controller at655. In one embodiment,storage system100 updates the current controller of the LUN in LUN ownership table115 when it receives the notice from the host system. The host then sends/receives data to/from the LUN through the new current controller (660).
• A determination is made on whether to continue processing requests from applications such as application605 (decision670). If host processing should continue,decision670 branches to the “Yes” branch, whereupon the host system receives and processes application requests. This looping continues until host processing should terminate, at whichpoint decision670 branches to the “No” branch, whereupon processing ends at680.
• FIG. 7 is diagram showing an example of a graphical representation a storage system maintaining a balanced traffic load between two storage controllers by dynamically adjusting preferred controller ownership of logical units within the storage system.
• Graph700 shows a relative logical unit traffic load (controller traffic load ratio710) over time between two storage controllers. At time t0, the relative logical unit traffic load is balanced betweenstorage controller 1105 andstorage controller 2110. For example,storage system100 may split the amount of preferred controller ownerships between the two different storage controllers whenstorage system100 boots up (e.g.,525 inFIG. 5).
• As time progress toward time t1, the amount of logical unit traffic increases throughstorage controller 1105 relative to the amount of logical unit traffic throughstorage controller 2110, hence controllertraffic load ratio710 has a positive slope. At time t1, controllertraffic load ratio710 reaches auto-balance threshold720, which may be set by a system administrator through a user interface, such aswindow200 shown inFIG. 2A. As such,storage system100 changes the preferred controller ownership of one or more logical units in order to move some of the logical unit traffic fromstorage controller 1105 tostorage controller 2110. As shown inFIGS. 3A and 3B,storage system100 changes the preferred controller ownership of a logical unit by changing the corresponding preferred controller identifier in logical unit ownership table115. In turn, when a host system sends an ownership inquiry tostorage system100,storage system100 sends a response with the updated preferred controller information.
• Asstorage system100 moves preferred controller ownership of one or more logical units fromstorage controller 1105 tostorage controller 2110, the host systems begin to pass more logical unit data traffic throughstorage controller 2110. In turn, logicalunit traffic ratio710 balances betweenstorage controller 1105 andstorage controller 2110. As time progresses to time t2, controllertraffic load ratio710 reaches auto-balance threshold730. For example, assuming that a controller traffic load ratio during a balanced load is “0,”thresholds720 and730 may be +10% and −10%, respectively (or 0.10 and −0.10).
• At time t2,storage system100 changes the preferred controller ownership of one or more logical units in order to move some of the logical unit traffic fromstorage controller 2110 tostorage controller 1105 by changing the corresponding preferred controller identifier in logical unit ownership table115. By dynamically re-assigning preferred controller ownership of the logical units, the traffic load passed through the storage controllers remains balanced and, in turn, bottlenecks are reduced.
• FIG. 8 illustratesinformation handling system800, which is a simplified example of a computer system capable of performing the computing operations described herein.Information handling system800 includes one ormore processors810 coupled toprocessor interface bus812.Processor interface bus812 connectsprocessors810 toNorthbridge815, which is also known as the Memory Controller Hub (MCH).Northbridge815 connects tosystem memory820 and provides a means for processor(s)810 to access the system memory.Graphics controller825 also connects toNorthbridge815. In one embodiment,PCI Express bus818 connectsNorthbridge815 tographics controller825.Graphics controller825 connects to displaydevice830, such as a computer monitor.
• Northbridge815 andSouthbridge835 connect to each other usingbus819. In one embodiment, the bus is a Direct Media Interface (DMI) bus that transfers data at high speeds in each direction betweenNorthbridge815 andSouthbridge835. In another embodiment, a Peripheral Component Interconnect (PCI) bus connects the Northbridge and the Southbridge.Southbridge835, also known as the I/O Controller Hub (ICH) is a chip that generally implements capabilities that operate at slower speeds than the capabilities provided by the Northbridge.Southbridge835 typically provides various busses used to connect various components. These busses include, for example, PCI and PCI Express busses, an ISA bus, a System Management Bus (SMBus or SMB), and/or a Low Pin Count (LPC) bus. The LPC bus often connects low-bandwidth devices, such asboot ROM896 and “legacy” I/O devices (using a “super I/O” chip). The “legacy” I/O devices (898) can include, for example, serial and parallel ports, keyboard, mouse, and/or a floppy disk controller. The LPC bus also connectsSouthbridge835 to Trusted Platform Module (TPM)895. Other components often included inSouthbridge835 include a Direct Memory Access (DMA) controller, a Programmable Interrupt Controller (PIC), and a storage device controller, which connectsSouthbridge835 tononvolatile storage device885, such as a hard disk drive, usingbus884.
• ExpressCard855 is a slot that connects hot-pluggable devices to the information handling system.ExpressCard855 supports both PCI Express and USB connectivity as it connects toSouthbridge835 using both the Universal Serial Bus (USB) the PCI Express bus.Southbridge835 includesUSB Controller840 that provides USB connectivity to devices that connect to the USB. These devices include webcam (camera)850, infrared (IR)receiver848, keyboard andtrackpad844, andBluetooth device846, which provides for wireless personal area networks (PANs).USB Controller840 also provides USB connectivity to other miscellaneous USB connecteddevices842, such as a mouse, removable nonvolatile storage device845, modems, network cards, ISDN connectors, fax, printers, USB hubs, and many other types of USB connected devices. While removable nonvolatile storage device845 is shown as a USB-connected device, removable nonvolatile storage device845 could be connected using a different interface, such as a Firewire interface, etcetera.
• Wireless Local Area Network (LAN)device875 connects to Southbridge835 via the PCI orPCI Express bus872.LAN device875 typically implements one of the IEEE 802.11 standards of over-the-air modulation techniques that all use the same protocol to wireless communicate betweeninformation handling system800 and another computer system or device.Optical storage device890 connects toSouthbridge835 using Serial ATA (SATA)bus888. Serial ATA adapters and devices communicate over a high-speed serial link. The Serial ATA bus also connectsSouthbridge835 to other forms of storage devices, such as hard disk drives.Audio circuitry860, such as a sound card, connects toSouthbridge835 viabus858.Audio circuitry860 also provides functionality such as audio line-in and optical digital audio inport862, optical digital output andheadphone jack864,internal speakers866, andinternal microphone868.Ethernet controller870 connects toSouthbridge835 using a bus, such as the PCI or PCI Express bus.Ethernet controller870 connectsinformation handling system800 to a computer network, such as a Local Area Network (LAN), the Internet, and other public and private computer networks.
• WhileFIG. 8 shows one information handling system, an information handling system may take many forms. For example, an information handling system may take the form of a desktop, server, portable, laptop, notebook, or other form factor computer or data processing system. In addition, an information handling system may take other form factors such as a personal digital assistant (PDA), a gaming device, ATM machine, a portable telephone device, a communication device or other devices that include a processor and memory.
• The Trusted Platform Module (TPM895) shown inFIG. 8 and described herein to provide security functions is but one example of a hardware security module (HSM). Therefore, the TPM described and claimed herein includes any type of HSM including, but not limited to, hardware security devices that conform to the Trusted Computing Groups (TCG) standard, and entitled “Trusted Platform Module (TPM) Specification Version 1.2.” The TPM is a hardware security subsystem that may be incorporated into any number of information handling systems, such as those outlined inFIG. 9.
• FIG. 9 provides an extension of the information handling system environment shown inFIG. 8 to illustrate that the methods described herein can be performed on a wide variety of information handling systems that operate in a networked environment. Types of information handling systems range from small handheld devices, such as handheld computer/mobile telephone910 to large mainframe systems, such asmainframe computer970. Examples ofhandheld computer910 include personal digital assistants (PDAs), personal entertainment devices, such as MP3 players, portable televisions, and compact disc players. Other examples of information handling systems include pen, or tablet,computer920, laptop, or notebook,computer930,workstation940,personal computer system950, andserver960. Other types of information handling systems that are not individually shown inFIG. 9 are represented byinformation handling system980. As shown, the various information handling systems can be networked together usingcomputer network900. Types of computer network that can be used to interconnect the various information handling systems include Local Area Networks (LANs), Wireless Local Area Networks (WLANs), the Internet, the Public Switched Telephone Network (PSTN), other wireless networks, and any other network topology that can be used to interconnect the information handling systems. Many of the information handling systems include nonvolatile data stores, such as hard drives and/or nonvolatile memory. Some of the information handling systems shown inFIG. 9 depicts separate nonvolatile data stores (server960 utilizesnonvolatile data store965,mainframe computer970 utilizesnonvolatile data store975, andinformation handling system980 utilizes nonvolatile data store985). The nonvolatile data store can be a component that is external to the various information handling systems or can be internal to one of the information handling systems. In addition, removable nonvolatile storage device845 can be shared among two or more information handling systems using various techniques, such as connecting the removable nonvolatile storage device845 to a USB port or other connector of the information handling systems.
• While particular embodiments of the present disclosure have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, that changes and modifications may be made without departing from this disclosure and its broader aspects. Therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this disclosure. Furthermore, it is to be understood that the disclosure is solely defined by the appended claims. It will be understood by those with skill in the art that if a specific number of an introduced claim element is intended, such intent will be explicitly recited in the claim, and in the absence of such recitation no such limitation is present. For non-limiting example, as an aid to understanding, the following appended claims contain usage of the introductory phrases “at least one” and “one or more” to introduce claim elements. However, the use of such phrases should not be construed to imply that the introduction of a claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to disclosures containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an”; the same holds true for the use in the claims of definite articles.

Claims (7)

1. A method comprising:

determining, by a storage system, that a controller traffic load ratio between a first storage controller and a second storage controller has reached a threshold, wherein the first storage controller and the second storage controller correspond to at least one of a plurality of logical units included in the storage system;

selecting, by the storage system, one of the plurality of logical units; and

changing, by the storage system, a preferred controller ownership corresponding to the selected logical unit from the first storage controller to the second storage controller in response to the determination.

2. The method ofclaim 1 wherein the storage system configures the first storage controller and the second storage controller in an active/passive controller configuration.

3. The method ofclaim 1 wherein, prior to the determination that the controller traffic load ratio has reached the threshold, the method further comprises:

identifying a first data traffic amount passing through the first storage controller corresponding to one or more first logical units included in the plurality of logical units and;

identifying a second data traffic amount passing through the second storage controller corresponding to one or more second logical units included in the plurality of logical units; and

computing the controller traffic load ratio based upon the first data traffic amount and the second data traffic amount.

4. The method ofclaim 1 further comprising:

subsequent to changing the preferred controller ownership, receiving an ownership inquiry from a host system, the ownership inquiry including a logical unit identifier corresponding to the selected logical unit; and

sending an ownership response to the host system, wherein the ownership response includes a preferred controller identifier corresponding to the second storage controller.

5. The method ofclaim 1 further comprising:

displaying, by the storage system, an ownership configuration window to a user;

receiving an ownership configuration selection from the user;

determining that the ownership configuration selection is a dynamic ownership selection; and

configuring the storage system to balance the controller traffic load ratio, wherein the balancing includes changing one or more preferred controller ownerships of one or more of the plurality of logical units when the controller traffic load ratio reaches the threshold.

6. The method ofclaim 6 wherein the threshold is an auto-balance threshold received from the user.

7. The method ofclaim 1 wherein each of the plurality of logical units corresponds to at least a portion of a physical storage device.

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