System and method for simulating performance of one or more data storage systems

[0001] This application is related to co-pending U.S. patent application 10/259,010 by Dan Aharoni et al., filed Sep. 27, 2002, and is assigned to the same assignee as this invention.

[0002] A portion of the disclosure of this patent document contains command formats and other computer language listings, all of which are subject to copyright protection. The copyright owner, EMC Corporation, has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

[0003] This invention relates generally to managing and analyzing data in a data storage environment, and more particularly to a system and method for simulating performance in such an environment.

[0004] Computer systems are constantly improving in terms of speed, reliability, and processing capability. As is known in the art, computer systems which process and store large amounts of data typically include a one or more processors in communication with a shared data storage system in which the data is stored. The data storage system may include one or more storage devices, usually of a fairly robust nature and useful for storage spanning various temporal requirements, e.g. disk drives. The one or more processors perform their respective operations using the storage system. Mass storage systems particular those of the disk array type have centralized data as a hub of operations all driving down costs. But performance demands placed on such mass storage have increased and continue to do so.

[0005] Design objective for mass storage systems include cost, performance, and availability. Objectives typically include are a low cost per megabyte, a high I/O performance, and high data availability. Availability is measured by the ability to access data. Often such data availability is provided by use of redundancy such as well-known mirroring techniques.

[0006] One problem encountered in the implementation of disk array data storage systems concerns optimizing the storage capacity while maintaining the desired availability and reliability of the data through redundancy. It is important to allocate as closely as possible the right amount of storage capacity with going over or under significantly because of cost and necessity but this is a complex task. It has required great deal of skill and knowledge about computers, software applications such as databases, and the very specialized field of data storage. Such requisite abilities have long been expensive and difficult to access. There remains and probably will be an increasing demand for and corresponding scarcity of such skilled people.

[0007] Determining the size and number of disk array or other data storage system needed by a customer requires information about both space, traffic and a desired quality of service. It is not sufficient to size a solution simply based on the perceived quantity of capacity desired, such as the number of terabytes believed to be adequate.

[0008] In addition to general capacity planning problems with data storage systems other complexities may arise. One such complexity arise when there is an interest in merging existing data storage systems with newer or fewer data storage systems. Such consolidation helps a customer reduce operating costs by decreasing the number of storage systems, and migrating the data to fewer and/or newer, larger capacity, more efficient storage systems. Consolidation may be of interest for some of the following reasons: saving footprint space; reducing the cost of utilities; simplifying management and reducing management costs; reducing hardware inventory costs; and upgrading to new technology. On the other hand there are costs associated with such a change and there is need for a simple tool to allow for the analysis of such a change and to determine an optimum solution, and in particular with regard to performance requirements and desired characteristics.

[0009] There is a long-felt need for a computer-based tool that would allow a straight-forward non-complex way to allocate proper storage capacity while balancing cost, growth plans, workload, and performance requirements and further if such a tool would be useful for analyzing consolidation or merging operations. This would be advancement in the computer arts with particular relevance in the field of data storage.

[0010] To overcome the problems described above and to provide the advantages also described above, the present invention is a system and method for simulating performance in a data storage environment. Such simulations may be used to isolate problem areas and for modeling and capacity planning.

[0011] In one embodiment the method includes the steps of receiving configuration data related to the configuration of one or more data storage systems, receiving performance characteristics of work performed on the one or more data storage systems, and then simulating performance on the one or more data storage systems using the configuration data and performance characteristics.

[0012] In an embodiment of a system a computer with display and memory are configured with computer-executable program logic capable of performing steps similar or identical to those described above with reference to the embodiment of the method.

[0013] In another embodiment, a program product includes a computer-readable medium having code included on the medium configured to carry out computer-executed steps that are similar or identical to those described above with reference to the embodiment of the method.

[0030] The methods and apparatus of the present invention are intended for use with data storage systems, such as the Symmetrix Integrated Cache Disk Array system available from EMC Corporation of Hopkinton, Mass. Specifically, this invention is directed to a method and system for simulating performance of one or more data storage systems and which may be useful for applications such storage capacity planning, performance analysis, and problem and fault isolation in a storage environment design.

[0031] The methods and apparatus of this invention may take the form, at least partially, of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, random access or read only-memory, or any other machine-readable storage medium. When the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The methods and apparatus of the present invention may be embodied in the form of program code that is transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via any other form of transmission. And may be implemented such that when the program code is received and loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates analogously to specific logic circuits.

[0032] The program code (software-based logic) for carrying out the method is embodied as part of the system described below beginning with reference to FIG. 1. One aspect of the invention is embodied as a method that is described below with reference to FIGS. 3-6. User Interface Screens for using the invention are shown in FIGS. 7-14.

[0033] Referring now to FIG. 1, reference is now made to a network or local system 100 for which the invention is particularly useful and typically includes a plurality of data storage systems, such as data storage system 100, 102, and 104. The data storage systems are useful if the simulation system tool 114 including computer-executable program code 342 is to use configuration data 106, 108, and 110 of the respective data storage systems in conjunction with workload characteristics form the preferred workload analyzer 112 files (.btp format available as part of EMC's ECC software program; EMC Corporation is based in Hopkinton, Mass.). However optionally, the simulation tool 114 may use user or model data 116 if there are not specific data storage systems (generally n−n+i) to be merged into fewer systems than n+1, e.g., target or model data storage system 124. The target system 124 may also be derived from the user of model data operated on by the data storage simulation tool using the workload files 112, to yield a capacity planning analysis 118, a system and component performance analysis. The merge analysis 122 specifically envisions the need to merge the n+1 storage systems into a target system.

[0034] The simulation system or tool preferably uses software 342 for carrying out the method steps described in method steps shown in FIGS. 2-6 and may work on a general purpose digital computer turning such a computer into a special purpose computer comprising an apparatus for carrying out the processes of this invention. The software may be used with any type of data storage system but has been used with a preferred EMC Symmetrix system and may also be used with an EMC Clariion data storage system as well as those of other manufacturers. For exemplary purposes an EMC data storage system is described in the method steps and in conjunction with the user interface screens shown in FIGS. 7-14.

[0035] As has been stated, in a preferred embodiment the data storage system to be configured is a Symmetrix Integrated Cache Disk Array available from EMC Corporation of Hopkinton, Mass. However, it will be apparent to those with skill in the art that there is no limit to the use of this invention for any system including data storage. Nevertheless, regarding the preferred embodiment, such a data storage system and its implementation is fully described in U.S. Pat. No. 6,101,497 issued Aug. 8, 2000, and also in U.S. Pat. No. 5,206,939 issued Apr. 27, 1993, each of which is assigned to EMC the assignee of this invention and each of which is hereby incorporated by reference. Consequently, the following discussion makes only general references to the operation of such systems.

[0036] Generally a Symmetrix data storage system includes a system memory and sets or pluralities and of multiple data storage devices or data stores. The system memory can comprise a buffer or cache memory; the storage devices in the pluralities and can comprise disk storage devices, optical storage devices and the like. However, in a preferred embodiment the storage devices are disk storage devices. The sets represent an array of storage devices in any of a variety of known configurations.

[0037] In such a data storage system, a computer or host adapter provides communications between a host system and the system memory and disk adapters and provides pathways between the system memory and the storage device pluralities. Regarding terminology related to the preferred Symmetrix system, from the host adapter toward the computer or host is sometimes referred to as the front end and from the disk adapters toward the disks is sometimes referred to as the back end. A bus interconnects the system memory, the host adapters and the disk adapters. Although not shown such a bus could be used with switches to provide discrete access to components of the system.

[0038] Each system memory is used by various elements within the respective systems to transfer information and interact between the respective host adapters and disk adapters. A service processor may also be used in communication with system memory particularly for maintenance, service needs, and collection of performance data. The service processor is typically a well-known laptop computer, i.e. a general-purpose digital computer, but which may be outfitted with the software-driven simulation system 114 of this invention to comprise a special purpose digital computer for carrying out the processes of this invention.

[0039] The simulation system or tool 114 may be used to determine the feasibility of consolidating a number of storage systems to fewer or newer data storage system units, this is sometimes referred to as a “merge” operation. The tool is useful for examining and calculating the utilization of components within the system to be consolidated or merged, such a system may be referred to as a source for a consolidating or merging operation. The tool may also be used to evaluate the performance of a number of different workloads on one or more data storage systems, including a system for which others are merged into, which may be referred to as a target configuration or system. When the tool is used for planning purposes the optimum system derived from the analysis may also be the target system even though no merge operation may be planned, and in such a case user desired performance data may be used to arrive at such a target.

[0040] The tool 114 helps to define consolidation mapping and evaluates whether this mapping is favorable for a new upgrade data storage system in terms of performance. The tool may be further used to examine the utilization of components within the new target data storage system and generates a near optimal file (e.g. binary file) that can be used for such a configuration.

[0041] All the utilization and calculations are based on modeling the internal operations and processes inside the target data storage system. The accuracy of the calculations is based on the accuracy of the input workload, which is discussed in more detail below. If the workload changes, this evaluation may change significantly. The tool 114 analyzes the utilization of components, as well as the entire system, and may be used for considering workloads from data storage systems being used with Open Systems host computers and Mainframe host computer systems using proprietary schemes.

[0042] FIG. 15 shows a tool 114 as generally including a general purposed digital computer including memory 340 (e.g., conventional electronic memory) in which is stored computer-executable program code 342 that enables the method of the invention (FIGS. 2-6) and enables display of user screens (FIGS. 7-14) on display 346 to comprise GUI 342. The general-purpose digital computer becomes a specialized unique and novel machine because of the code or logic 342, which in a preferred embodiment is software but may be hardware. Logic or code 342 may also be stored and read for operation on computer readable medium 352. A user input device 350, such as a well-known mouse or keyboard allows the user to interface with the computer including its special logic.

[0043] Now for a better understanding of an embodiment of method steps of this invention the steps are described in detail with reference to FIGS. 3-6, which are explained with reference to user interface display screens shown in FIGS. 7-14.

[0044] Referring to FIG. 2, an overview of the method steps of simulation is shown, wherein the simulation action may include some or all of the steps shown. In step 130 input is given by a user or under computer control for configuration, workload, and/or user performance data. In step 132, the simulation tool 114 analyzes the system load and percent (%) utilization of each component in the system. Percent utilization refers to the amount of time a component or system is working versus its respective idle time. Using the analysis model target configurations can be determined in step 132 and the load may be balanced and/or the model target optimized for performance in step 136. Specifically how the general steps are carried out depend on the objectives of the user, i.e. using the tool for merging of two or more data storage systems or performance analysis for optimization or capacity planning or fault isolation and general design purposes. Other uses for the tool may occur to those skilled in the art in view of the teachings herein, and such uses should not limited except by the claims appearing herein and their equivalents, which may not be presently foreseeable.

[0045] Reference is made below to FIGS. 3-6, more specific road-map type of method steps for employing this invention are given and are best understood with reference to user screens shown in FIGS. 7-14. In FIG. 6, step 140 is directed toward “Add Box,” which means determine whether a data storage system is to be merged, and if so its configuration data is added in step 142. The configuration data available from cache of the preferred Symmetrix or a service processor in communication with the data storage system is typically a binary (.bin) file that is added in step 142, and workload characteristics may be also loaded from the preferred EMC ECC Workload Analyzer (a .btp format) file in step 146. Alternatively if using user data in step 150, the workload characteristics desired, predicted, or needed based on the type of applications being processed on the data storage system can be added. For a particular data storage system, and for each type of I/O, the simulation tool 114 maintains a database of each component's execution, including factors such as time of execution and operation executed on each such component.

[0046] Performance characteristics such as IO operations are considered that include number of read hits, read misses, sequential reads, least recently used writes (i.e., re-writes), and write pending operations. A write operation means data is requested to be placed on the disk whereas a read operation means data is requested to be viewed but not changed and typically this involves loading from disk or electronic memory such as cache. Such cache or system memory is often employed to avoid mechanical lags associated with actual disk reads or writes. A random read hit means that data requested to be read from a random request was found in cache. On the other hand a random read miss means the data was not found in cache in response to a similar request. Sequential reads refers to a situation where a read request following an immediate preceding request is for data stored on disk in an immediately following sequence such as a data block. In such a case, cache can be used quite effectively to avoid going to disk, e.g., by pre-fetching a certain amount of sequentially arranged data from disk into cache. Least Recently Used writes (LRU writes) refer to regular writes to cache, which require standard LRU management. Write Pending writes (WP writes) refer to writes which are written into write pending (WP) slots in cache, which enable a more efficient write operation in terms of resource usage. An example of WP writes are cases where the same address in written and re-written a number of times over and over.

[0047] Whether using data storage system data (step 148) or user data (step 150), continuation step A flows into identical continuation step A shown on FIG. 4, and which in turn flows into step 154. In step 154, the user may deselect ports and/or volumes, which will decrease the workload on the data storage system, this may be done using the user interface screens described with reference to FIGS. 7-14 below. In step 156, the user may then check the check active configuration after such an action for meeting requirements, and then the system performance simulation system or tool can analyze system load in step 158 and calculate utilizations in step 160. If more boxes are to be added into a merge then the answer is “YES,” to the query posed in the interrogatory step 162, and continuation Step B flows back into Step 140 of FIG. 3, and a loop of steps 140-162 repeats until the answer to the question is “No,” and processing flows into continuation Step C which in turn flows to FIG. 5.

[0048] Referring now to FIG. 5, after continuation Step C, the target configuration may be determined in Step 164. The system load for the target is calculated in Step 166, and a balanced target utilization is calculated in Step 168, so that if needed configuration values may be adjusted in step 170. If the values are to be adjusted (“yes,” to the query of Step 170, then processing flows to continuation step E which in turn flows to Step 164 and the steps 164-170 are repeated until the query answer is “No.” In such case, processing flows to continuation Step D and then to FIG. 6.

[0049] Referring to FIG. 6, following Continuation Step D, in a preferred embodiment, the back end of the target storage system may be optimized, creating a binary file in Step 172 and the front end similarly optimized in Step 174. Then a component analysis in Step 176 will identify any problem components or areas, which will be further explained with reference to FIGS. 11-14 below. If the performance is acceptable, or the query posed in step 178, then the merge consolidation is considered complete in step 180, but if not then continuation E is followed to return processing back to Step 164 (FIG. 5) and a loop continues through to Step 178 until the performance is deemed acceptable. Techniques for increasing performance and in accordance with the steps above include reconfigure the data storage system to have more resources, or ‘faster’ components, such as Fibre channel and over the well-known SCSI interfaces.

[0050] Example of user interface screens for carrying out some or all of the method steps described above are shown in FIGS. 7-14. Referring to FIG. 7, screen 190 including menu action bar 192 with user actions 192 (e.g., file, box, target, optimize, reports, tools, and help) is presented for a user who wishes to merge or consolidate data storage systems as described above. Clicking on the “Source Boxes” field 196, presents user information area 198, including “Source Box,” “Max IO's/sec,” “max MB/sec,” and may also contain other performance characteristics fields (not shown for simplicity). A message area 200 is available for conveying related information to a user. The user may specify the number of target boxes for the merge in field 202. Field area 204, inclusively has several action field buttons including “Add Box,” “Target Configuration,” “Balanced Utilization,” and “Per Component Analysis.”

[0051] In FIG. 8, an example screen 206 is shown. Once a user has made a particular box selection identified in field area 208 (in this example “Box_1”) the type of desired action may be chosen using the Options button 210. Field area 212 shows a balanced option selected to a current system for consolidation (the volumes included are shown in the message area) 213. Field area 218 allows selection of whether a data storage system data (e.g. Symmetrix or Symm Data) or user data, and then a selection of a configuration binary file to load. Other actions selectable in user area 218 include “Load WLA btp file,” wherein performance characteristics are selected from the preferred WLA file as described above. Other user-selectable actions include “Calculate System Load,” “Analyze Load,” “Enter User Data,” “Configuration,” and “Utilization.” The user may also estimate the amount of growth expected, e.g. 10%.

[0052] FIG. 9 shows a user interface screen 220 useful for checking and adjusting a configuration of a data storage system, either the target system or one under investigation. Conveniently, there are two action tabs provided in the screen window: “Complete” tab 224 and “Active” tab 226. The Complete tab displays the configuration found in the preferred Impl.bin file and displays the configuration of the entire system. A “Box Type” tab in the presented window area of tab 224 allows the user to select the appropriate data storage system type, e.g., the example Symmetrix 5× or Symmetrix 4.8 type systems. Selecting the appropriate system allows the simulation tool 114 to adjust the resources to reflect the user's choice. For example, the number of logical volumes (#LVs) in the Complete window shows the total number of logical volumes in the box, whether or not they are mapped to the back end in the preferred example Symmetrix data storage system.

[0053] FIG. 10 shows the window presented on screen 220 when the Active configuration tab is selected. This window displays only the active resources (e.g., channels/logical volumes) a user has selected, and takes into account only the active resources chosen. The number of logical volumes (#LVs) in the Active window shows only the number of active logical volumes (those that contribute to the system load). Other information is also presented which one skilled in the art will recognize that in combination with the method steps and the system overview presented above provides an advancement in the computer arts. This invention is not to be limited by the examples given, but only by the claims and their equivalents, some of which may not be foreseeable at present.

[0054] FIG. 11 shows a component analysis map screen 230 of an entire data storage system. The tool 114 enables a user to view utilization of each component in a source or target data storage system. The option is provided to view in graphical (FIGS. 12 and 13, discussed below) or map format (FIG. 11). The mapped view represents the maximum utilization of each component over all the timestamps or per a particular timestamp (i.e. point in time). A title area 232 and action menu bar area 234 serve to respectively inform and allow the user to interact in conventional ways of Windows based software. However, the rest of the mapped view presents a completely novel way for a user to explore the utilization and potential problems of a target or current data storage system. Area 238 generally shows the utilization of each component, which is color coded, e.g. using red to identify over-used components (shown here in FIG. 11, as graphically coded due to lack of color drawings used herein) to a usage chart shown in Legend area 236. A timestamp area 240 allows the user to look at usage over any selected time.

[0055] Generally, regarding identification of components in the presented window of screen 230, the following applies, for this example. Presented from top to bottom on screen 230 (FIG. 11) are: area 243: front-end ports; area 244: front-end CPUs; area 245: front-end boards (i.e. the components on board to the bus; area 246: memory boards; area 247: buses; area 248: back-end boards; area 249: back-end CPUs; area 250 back-end ports; area 251: physical disks identified by volume id's. This example is of course for the preferred exemplary case of an EMC Symmetrix Data Storage System. However, one skilled in the art will recognize the general mapping scheme would apply to any data storage system other than the exemplary case.

[0056] Returning to the exemplary case shown in FIG. 11, when a mouse cursor is moved over a component screen representation, e.g. example component screen representation 242 in general screen area 247 the utilization is shown presented on the screen for the user to read. In the presented example, The Bus-top low: is being used at 92% utilization at the time 12:24. This implies alarmingly high traffic and alerts a user of potential problem areas to address for the target or current system. It should be understood, that the invention enables, although not shown in the drawings simple text messages (not shown) related to utilization or other performance considerations. Also, a user can simply tell a lot by glancing at the easy to read map, e.g. many disk drives, e.g. volume 1A-0 are being under-utilized, 10% in the example, while others, e.g. volume 9A-0 are being used at a good rate of about 40%. Thus, the invention, along with its other advantages, is also useful for determining utilization of each component in a system and for determining utilization of a system itself, whether the system is being currently employed or is one being simulated, or modeled, for design purposes or for consolidation or capacity planning or general performance analysis. Moreover, the simplicity of using the tool 114 allows those with simple skills in the computer area to make well-reasoned decisions regarding data storage, heretofore, an area requiring complex skills and a wealth of hard-earned experience.

[0057] Reference is made below to FIGS. 12-14. FIGS. 12 and 13 show a performance graph 254 and 256 on screens 250 and 260, respectively. FIG. 12 shows utilization for an entire data storage system, while FIG. 13 depicts what is visible for a user who selects a particular component, in general component selection 258 (FIG. 12) and 263 (FIG. 13) wherein in this example front-end boards for a preferred EMC Symmetrix data storage system are selected in field selection area 264 (also FIG. 13). For each screen, a toolbar 252 is located at the top of the screen. The toolbar contains buttons for performing tasks such as saving and printing the chart in a format generally known by users of operating systems such as Microsoft. The vertical axis on graphs 254 and 260 (FIGS. 12 and 13, respectively) represents resource utilization in percentages. The horizontal axis represents time periods for given workloads. The lines or performance curves in the graph show snapshots of the utilization data over specified time periods. FIG. 14 is a screen 280 showing a graphical map 282 of utilization of just the disks that are individually identified by volume identifier area 282. Area 284 allows user selection similar to that described above with reference to FIGS. 12 and 13.

[0058] When considering utilizations the following points are factored by the tool and the user may also consider when using the tool. Consider the following when analyzing utilizations. Loads and utilizations do not necessarily behave empirically in a linear manner. For example, if one measures a 60% utilization for a particular workload, adding 10% to this workload may result in a 90% utilization, not 70%, as one might expect. Therefore when analyzing utilization, it is good practice to consider granularity or resolution. Utilization calculation is based on reports, which average the data on a very large granularity, but real I/O bursts in a typical workload environment that a customer may see. In consideration of this the simulation tool offers through the user interface screens described herein two options: a “Balanced” option assumes the load to be evenly distributed between all the resources, and a “Per Component” option reports the actual utilization for each component. The analysis of the utilizations for a given data storage system may be different for different components. The X-axis on the Utilization charts warns the user of potential bottlenecks and various options and changes are allowed to reach desired optimization in view of the analysis.

[0059] A system and method for simulating performance on one or more data storage systems and using such simulation information has been described. Having described a preferred embodiment of the present invention, it may occur to skilled artisans to incorporate these concepts into other embodiments. Nevertheless, this invention should not be limited to the disclosed embodiment, but rather only by the spirit and scope of the following claims and their equivalents.