Patent Application
20140304548
1. Field of the Invention
This invention relates to techniques for intelligently and efficiently rebuilding redundant arrays of independent storage drives (RAIDS).
2. Background of the Invention
Redundant arrays of independent storage drives (RAIDS) are used extensively to provide data redundancy in order to protect data and prevent data loss. Various different “RAID levels” have been defined, each providing data redundancy in a different way. Each of these RAID levels provides data redundancy in a way that if one (or possibly more) storage drives in the RAID fail, data in the RAID can still be recovered.
In some cases, predictive failure analysis (PFA) may be used predict which storage drives in a RAID are going to fail. For example, events such as media errors, as well as the quantity and frequency of such events, are indicators that may be used to predict which storage drives will fail as well as when they will fail. This may allow corrective action to be taken on a RAID prior to a storage drive failure. For example, a storage drive that is predicted to fail may be removed from an array and replaced with a new drive prior to failure. Data may then be rebuilt on the new drive to restore data redundancy.
Unfortunately, PFE is not always accurate. In some cases, PFA may predict that a certain drive is going to fail when in reality a different drive fails first. In certain cases, an erroneous prediction can create situations that compromise data integrity. For example, if a drive that is predicted to fail is replaced with a new drive and, while data is being rebuilt on the new storage drive, a different drive fails, all or part of the data in the array may be permanently lost. Data loss can have mild to very severe consequences for an organization.
In view of the foregoing, what are needed are techniques to more intelligently and efficiently maintain arrays of independent storage drives (RAIDS). Ideally, in cases where a storage drive in a RAID is predicted to fail, such techniques will allow the RAID to be serviced in a way that better protects data while the RAID is being rebuilt. Ideally, such techniques will also minimize the amount of time a technician needs to service a RAID.
The invention has been developed in response to the present state of the art and, in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available apparatus and methods. Accordingly, the invention has been developed to enable users to more efficiently and intelligently service redundant arrays of storage drives. The features and advantages of the invention will become more fully apparent from the following description and appended claims, or may be learned by practice of the invention as set forth hereinafter.
Consistent with the foregoing, a method for servicing a redundant array of independent storage drives (i.e., RAID) is disclosed herein. In one embodiment, such a method includes performing a service call on the RAID by performing the following steps: (1) determining whether the RAID includes one or more consumed spare storage drives; (2) in the event the RAID includes one or more consumed spare storage drives, physically replacing the one or more consumed spare storage drive with one or more non-consumed spare storage drives; and (3) initiating a copy process that copies data from a storage drive that is predicted to fail to a non-consumed spare storage drive associated with the RAID. The service call may then be terminated. After the service call is terminated, the method waits for an indication that a number of non-consumed spare storage drives in the RAID has fallen below a selected threshold.
A corresponding apparatus and computer program product are also disclosed and claimed herein.
In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:
It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention. The presently described embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.
As will be appreciated by one skilled in the art, the present invention may be embodied as an apparatus, system, method, or computer program product. Furthermore, the present invention may take the form of a hardware embodiment, a software embodiment (including firmware, resident software, micro-code, etc.) configured to operate hardware, or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “module” or “system.” Furthermore, the present invention may take the form of a computer-usable storage medium embodied in any tangible medium of expression having computer-usable program code stored therein.
Any combination of one or more computer-usable or computer-readable storage medium(s) may be utilized to store the computer program product. The computer-usable or computer-readable storage medium may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable storage medium may 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), a portable compact disc read-only memory (CDROM), an optical storage device, or a magnetic storage device. In the context of this document, a computer-usable or computer-readable storage medium may be any medium that can contain, store, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
Computer program code for carrying out operations of the present invention 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. Computer program code for implementing the invention may also be written in a low-level programming language such as assembly language.
Embodiments of the invention may be described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus, systems, and computer program products. 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, may be implemented by computer program instructions or code. 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.
The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means 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 or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus 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.
Referring to
As shown, the network architecture 100 includes one or more computers 102, 106 interconnected by a network 104. The network 104 may include, for example, a local-area-network (LAN) 104, a wide-area-network (WAN) 104, the Internet 104, an intranet 104, or the like. In certain embodiments, the computers 102, 106 may include both client computers 102 and server computers 106 (also referred to herein as “hosts” 106 or “host systems” 106). In general, the client computers 102 initiate communication sessions, whereas the server computers 106 wait for requests from the client computers 102. In certain embodiments, the computers 102 and/or servers 106 may connect to one or more internal or external direct-attached storage systems 112 (e.g., arrays of hard-storage drives, solid-state drives, tape drives, etc.). These computers 102, 106 and direct-attached storage systems 112 may communicate using protocols such as ATA, SATA, SCSI, SAS, Fibre Channel, or the like.
The network architecture 100 may, in certain embodiments, include a storage network 108 behind the servers 106, such as a storage-area-network (SAN) 108 or a LAN 108 (e.g., when using network-attached storage). This network 108 may connect the servers 106 to one or more storage systems 110, such as arrays 110a of hard-disk drives or solid-state drives, tape libraries 110b, individual hard-disk drives 110c or solid-state drives 110c, tape drives 110d, CD-ROM libraries, or the like. To access a storage system 110, a host system 106 may communicate over physical connections from one or more ports on the host 106 to one or more ports on the storage system 110. A connection may be through a switch, fabric, direct connection, or the like. In certain embodiments, the servers 106 and storage systems 110 may communicate using a networking standard such as Fibre Channel (FC) or iSCSI.
Referring to
In selected embodiments, the storage controller 200 includes one or more servers 206. The storage controller 200 may also include host adapters 208 and device adapters 210 to connect the storage controller 200 to host devices 106 and storage drives 204, respectively. Multiple servers 206a, 206b may provide redundancy to ensure that data is always available to connected hosts 106. Thus, when one server 206a fails, the other server 206b may pick up the I/O load of the failed server 206a to ensure that I/O is able to continue between the hosts 106 and the storage drives 204. This process may be referred to as a “failover.”
In selected embodiments, each server 206 may include one or more processors 212 and memory 214. The memory 214 may include volatile memory (e.g., RAM) as well as non-volatile memory (e.g., ROM, EPROM, EEPROM, hard disks, flash memory, etc.). The volatile and non-volatile memory may, in certain embodiments, store software modules that run on the processor(s) 212 and are used to access data in the storage drives 204. The servers 206 may host at least one instance of these software modules. These software modules may manage all read and write requests to logical volumes in the storage drives 204.
One example of a storage system 110a having an architecture similar to that illustrated in
Referring to
As can be appreciated, organizing storage drives 204 into a RAID provides data redundancy that allows data to be preserved in the event one (or possibly more) storage drives 204 within the RAID fails. In a conventional RAID rebuild, when a drive 204 in a RAID fails, the failing drive 204 is replaced with a new drive 204 and data is then reconstructed on the new drive 204 using the data on the RAID's other drives 204. This rebuild process restores data redundancy in the RAID. Although usually effective, such a conventional RAID rebuild process has various pitfalls. For example, if another storage drive 204 were to fail while the already failed drive 204 is being rebuilt, all or part of the data in the RAID may be lost.
In order to prevent or reduce the chance of permanent data loss, a more intelligent RAID rebuild process using predictive failure analysis (PFA) may be used. As previously mentioned, by analyzing events such as media errors, PFA may be used predict if and when a storage drive 204 is going to fail. This may allow corrective action to be taken prior to the storage drive's failure. Instead of rebuilding data on a failing storage drive 204 from data on other drives 204 in the RAID, the data on the failing storage drive 204 may be copied to a spare storage drive 204 prior to its failure. For example,
Unfortunately, for a technician who is servicing a RAID, the intelligent rebuild process can consume additional time, potentially increasing costs. For example, using a conventional RAID rebuild process, a technician may physically pull a failing drive 204 from the RAID array and insert a new good drive 204. The data may then be rebuilt on the new drive 204 using data from the other good drives 204 in the RAID, thereby restoring data redundancy. Because the failed drive 204 has been removed from the RAID array, the technician can terminate the service call and physically leave the site. Using an intelligent rebuild process, however, the failing drive 204 must be left in the array until its data is copied to a new drive 204. This copy process can last a significant amount of time, possibly several hours. In some cases, a technician may need to wait for this process to complete prior to terminating the service call and physically leaving the site of the array so that the failing drive 204 can be pulled from service. As previously mentioned, this additional time can drive up service costs.
As will be explained in more detail hereafter, embodiments of the invention may provide the data-protection advantages of the intelligent rebuild process, while still providing the time-savings associated with conventional RAID rebuild processes. Embodiments of the invention rely on the fact that the array 300 may include one or more spare storage drives 204 (i.e., “non-consumed spares”) that may be used for deferred maintenance purposes. When additional drives 204 are needed in the array 300, the non-consumed spares 204 may be utilized, thereby reducing the need for a technician to physically visit the site where the array 300 is located and replace failed or failing drives 204. When a number of non-consumed spares 204 has fallen below a specified level (e.g., two), a technician may visit the site to replace consumed spares 204 with non-consumed spares 204 and/or provide other maintenance.
As shown in
Referring to
Referring to
The method 800 then determines 808 whether the array 300 contains at least one storage drive 204 that is predicted to fail, but has not already failed. If so, a technician may initiate 810 an intelligent RAID rebuild process that copies from the storage drives 204 that are predicted to fail to non-consumed spare storage drives 204. At this point, the technician may terminate 812 the service call. Terminating the service call 812 may include terminating the service call 812 prior to the completion of the intelligent RAID rebuild process initiated at step 810. Once the service call is terminated, the method 800 may wait 814 for an indication (such as a “call home” event or other event monitored at a remote site) that a number of non-consumed spare storage drives 204 has fallen below a selected threshold (e.g., two). If, at step 816, the number of non-consumed spare storage drives 204 is below the threshold, a new service call may be initiated 802 to replace the consumed spare storage drives 204 with non-consumed spare storage drives 204 and/or perform other maintenance.
The method 800 illustrated in
The method steps may, in certain embodiments, be performed as part of a “guided maintenance” process. Such guided maintenance may provide assistance to a technician in performing a service call. For example, a technician may physically visit a site hosting an array 300 and a computing system such as a hardware management console may lead the technician through a series of steps to service the array 300. In certain cases, the hardware management console may request that a technician confirm that various steps (e.g., physically replacing drives) have been completed so that new steps (e.g., intelligent RAID rebuild processes, etc.) can be performed. The technician may also initiate different processes (e.g., intelligent RAID rebuild processes, conventional RAID rebuild processes, drive replacement, etc.) by way of the hardware management console.
The flowcharts and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer-usable media according to various embodiments of the present invention. In this regard, each block in the flowcharts 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 illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, may be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
