Patent Application
20150100617
Pursuant to 35 U.S.C. §119, the present application claims priority to UK Patent Application No. 1317617.7, filed Oct. 4, 2013, the entire contents of which are incorporated herein by reference.
The present invention relates in general to the field of storage systems management, and in particular to a network attached storage system and a corresponding method for request handling in a network attached storage system. Still more particularly, the present invention relates to a data processing program and a computer program product for request handling in a network attached storage system.
The technical area of this invention is about network attached storage (NAS) client management strategies and their application in network attached storage (NAS) systems, especially a storage system supporting the CIFS (Common Internet File System) protocol; although the invention is not limited only for this application.
Network attached storage (NAS) systems provide their internal storage capacity via a network to network attached storage (NAS) clients such as servers, personal computers, mobile devices and others. Any such client may or may not access the network attached storage (NAS) at any time, so there is no dependable prediction of how much Input/output (I/O) load a network attached storage (NAS) system will experience. As I/O load increases, the network attached storage (NAS) system may not be able to serve all clients in time, causing disconnects of clients that are not served in time (timeout of the I/O request). Such disconnects are disruptive from a client perspective and as such expose a serious problem in today's network attached storage (NAS) environments.
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Processing time of requests 172 increases as the amount of concurrent requests 172 increases. In other words if more and more clients 180 issue requests 172 to a storage subsystem 100 the processing time for each individual client request 172 increases gradually approaching a timeout threshold To.
Given the above it is only a matter of loading a storage system 100 with enough I/O requests 172 to cause timeouts at the connected clients 180.
Observing common access to the storage system 100 of the network attached storage (NAS) systems 1 shows, that clients 180 or applications/processes on the client 180 send a service request 172 like store, read, create, delete etc. to the storage system 100, wait for completion and then issue the next request 172.
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If a completion time Tc, defined as time duration between process S300 “Send Request” and process 5340 “Receive Response”, exceeds the client timeout threshold value To, the request 172 is discarded and data might get lost if the application is not prepared to handle that situation.
The completion time Tc is mostly determined by process S320, “Serve Request”. The more requests 172 are received by multiple clients 180, the more the average service time increases, and with it the probability that an individual request 172 may take longer than the timeout threshold value To.
It is important to note that with enterprise storage systems 100 it is common that many clients 180 are issuing I/O requests 172 concurrently (thousands). An example for illustration are universities where thousands of students access data over a network attached storage (NAS) protocol that is stored on a single shared storage subsystem 100.
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The technical problem underlying the present invention is to provide a network attached storage system and a corresponding method for request handling in a network attached storage system, which are able to maintain client connection and to prevent timeout in a network attached storage and to solve the above mentioned shortcomings and pain points of prior art request handling in a network attached storage system.
According to the present invention this problem is solved by providing a network attached storage system having the features of claim 1, a method for request handling in a network attached storage system having the features of claim 9, a data processing program for request handling in a network attached storage system having the features of claim 14, and a computer program product for request handling in a network attached storage system having the features of claim 15. Advantageous embodiments of the present invention are mentioned in the subclaims.
Accordingly, in an embodiment of the present invention a network attached storage system comprises a storage system connected to at least one external device via an external network, wherein the storage system comprises at least one storage media and at least one controller presenting storage capacity of the storage system to the at least one external device. The at least one external device sends a request to the storage system, wherein the at least one controller receives and serves the request and sends a response to the requesting external device after serving the request. Further the at least one controller comprises a delay functionality, which introduces a variable length delay to an execution process of the request based on a current input/output load of the storage system, a maximum allowed request response time, a request completion time, and a measured current request execution time.
In further embodiments of the present invention, the at least one controller turns off the delay functionality completely, when an input/output load of the storage system falls below a certain load threshold value and no external device experiences a timeout condition, in which the completion time of the request exceeds the maximum allowed request response time value.
In further embodiments of the present invention, the delay functionality of the at least one controller measures the current request execution time after serving the request and determines the request completion time of the corresponding request based on the measured request execution time.
In further embodiments of the present invention, the delay functionality adds no delay to the execution process of the request, when the request completion time exceeds a certain threshold value, which is smaller than the maximum allowed request response time value.
In further embodiments of the present invention, the delay functionality adds an individual delay time duration to the execution process of the request, when the request completion time falls below a certain threshold value.
In further embodiments of the present invention, the delay functionality determines the individual delay time duration, so that the a sum of the measured request execution time and the individual delay time duration approaches the maximum allowed request response time.
In further embodiments of the present invention, the delay functionality determines the individual delay time duration by calculating a difference between the measured current execution time or the determined request completion time of the request and the maximum allowed request response time of the request.
In further embodiments of the present invention, the delay functionality determines an individual maximum allowed request response time for each external device.
In another embodiment of the present invention, a method for request handling in a network attached storage system comprising a storage system connected to at least one external device via an external network, wherein the storage system comprises at least one storage media and at least one controller presenting storage capacity of the storage system to the at least one external device, said method comprises: Sending a request to the storage system by the at least one external device, receiving and serving the request by the at least one controller of the storage system; introducing a variable length delay to an execution process of the request by a delay functionality of the at least one controller based on a current input/output load of the storage system, a maximum allowed request response time, a request completion time, and a measured execution time; sending a response to the requesting external device by the at least one controller; and receiving the response by the at least one external device.
In further embodiments of the present invention, the delay functionality is turned off completely, when an input/output load of the storage system falls below a certain load threshold value and no external device experiences a timeout condition, in which the completion time of the request exceeds the maximum allowed request response time value.
In further embodiments of the present invention, the current request execution time is measured after serving the request, and the request completion time of the corresponding request is determined based on the measured request execution time.
In further embodiments of the present invention, no delay time duration is add to the execution process of the request, when the request completion time exceeds a certain threshold value; and wherein an individual delay time duration is add to the execution process of the request, when the request completion time falls below a certain threshold value.
In further embodiments of the present invention, the individual delay time duration is determined in a way that a sum of the request execution time and the individual delay time duration approaches the maximum allowed request response time.
In another embodiment of the present invention, a data processing program for execution in a data processing system comprises software code portions for performing a method for request handling in a network attached storage system when the program is run on the data processing system.
In yet another embodiment of the present invention, a computer program product stored on a computer-usable medium, comprises computer-readable program means for causing a computer to perform a method for request handling in a network attached storage system when the program is run on the computer.
All in all, embodiments of the present invention introduce an intelligent delay functionality which introduces an I/O request delay of variable length. The delay functionality can be turned off completely when the system has low load and no clients experience timeouts. When turned on, the delay functionality will add no delay time to I/O requests that take long, thus it does not make the situation worse. Further, when turned on, the delay functionality adds a delay for all I/O requests that are well below the acceptable timeout threshold To of the clients. This delay is determined for each individual request. It is adjusted so that the completion time Tc approaches but stays below the client timeout threshold To. Since this delay is determined after serving the request, the delay duration can be exactly calculated, causing all requests to be served in a very similar time.
As a consequence keeping the sequential nature of individual clients in mind, the total amount of fast responding requests is reduced, in the case where the intelligent delay functionality is turned on. At first this might seem contra-productive but in the context of network attached storage (NAS) systems with many concurrent connected clients this adds a significant benefit. By doing this, embodiments of the present invention remove some load from the system, allowing it to reduce the average service time and thereby reduce the probability of individual requests exceeding the acceptable timeout threshold To of clients. It needs to be stressed again that an I/O request timing out is disruptive to clients while an I/O request that takes longer but does not timeout will fully be tolerated by the client.
In summary, to improve the short comings and problems of prior art solutions outlined in the background section embodiments of the present invention introduce an intelligent delay functionality which optionally adds a delay process for each service request with variable delay duration. This delay process is placed after the serving the actual request.
The above, as well as additional purposes, features, and advantages of the present invention will become apparent in the following detailed written description.
A preferred embodiment of the present invention, as described in detail below, is shown in the drawings, in which:
The present invention may be a system, a method, and/or a computer program product. Accordingly, aspects of the present invention 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.” The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention.
The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: 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), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.
Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device.
Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions 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). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention.
Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 readable program instructions.
These computer readable 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 readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks.
The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational processes to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement 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 instructions, which comprises one or more executable instructions for implementing the specified logical function(s). 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 carry out combinations of special purpose hardware and computer instructions.
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A connection 170 from an external device 180 via network 190 and an access point 120 to a controller 110A is used to read and write data to the storage system 100A. File-based data protocols like NFS, CIFS, FTP and HTTP are used to handle the data transfer between the external device 180 and the storage system 100A. The at least one external device 180 sends a request 172 to the storage system 100A, wherein the at least one controller 110A receives and serves the request 172 and sends a response 174 to the requesting external device 180 after serving the request 172. The at least one controller 110A comprises a delay functionality 112A, which introduces a variable length delay to an execution process of the request 172 based on a current input/output load of the storage system 100A, a maximum allowed request response time To, a request completion time Tc, and a measured current request execution time Te.
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The delay duration is determined by the difference of measured execution time Te of the request 172 and the overall suggested response time Tc by the delay functionality 112A of the I/O request controller 110A, for example. The I/O request controller 110A determines a target response time based on the overall system load. If it detects the system is overloaded, it will select the protocol based maximum acceptable response time.
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Thus if system load is increasing which is indicated by long average response times, the delay functionality 112A adds delay durations only to individual quick requests 172 that are still distant from the timeout threshold value To on average escalating response times.
In the shown embodiment the delay functionality 112A determines the maximum allowed response time To by individual connection, so that each client 180 could have a different timeout threshold value To based on a version of the client implementation, and individual requests will have delay durations that stay below the client timeout threshold limit To of the individual connection.
In an alternative embodiment a variable delay “response time goal” allows a smooth variation in a range from “no extra delay” to “maximum extra delay”, based on the detected load and/or an average response time.
Embodiments of the present invention furthermore permit even higher granular handling of client I/O requests than what is possible in prior art. In another embodiment the I/O request controller 110A together with the intelligent delay functionality 112A can treat particular clients 180 or pool of clients in a preferred way. Specific clients, for example connecting with a particular IP address, might be given higher priority and/or smaller and/or no I/O response time escalation than other connected clients given a higher response time escalation.
The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments 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 described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1317617.7 | Oct 2013 | GB | national |
