Managing a quorum device for a storage system

Abstract

A method, computer program product, and computer system for managing a quorum device for a storage system having network of storage controllers of storage clusters. includes: using a first storage controller as a volume-based quorum device 201 for a second storage controller, wherein the first storage controller is aware of being treated as a quorum device; taking snapshots of cluster state metadata 206 at known points and saving as quorum volumes; and recovering the storage cluster from the cluster state metadata in the event of a failure 207. The method may also include selecting recovery points for taking snapshots depending on the type of cluster state metadata, it may also include integrating storage-centric actions into a control flow of the quorum device. The method may create safeguarded copies of the metadata, and may store multiple copies for point-in-time recovery.

Description

BACKGROUND

[0001] The present invention relates to storage systems, and more specifically, to managing quorum devices for a storage system.

[0002] Copy services are a collection of features which allow storage systems to have, amongst other things, disaster recovery integrated into the IO path. This is achieved via Remote Copy features, by transmitting data to a partner storage system. The backup site performs the IO, notifies the primary site, and the IO is removed from the pending set. Copy services can make use of various techniques.

[0003] A pair of nodes within a single enclosure is known as an input / output (I / O) group. When a write operation is performed to a volume, the node that processes the I / O duplicates the data onto the partner node that is in the I / O group. After the data is protected on the partner node, the write operation to the host application is completed. The data is physically written to the disk later.

[0004] In distributed systems, a fault scenario can exist where more than one node believes they are the leader, in which case they can both accept writes, without any synchronization which can result in data loss and / or corruption. This is known as split-brain, and distributed systems rely on a mediator service to form a quorate group and avoid such conditions.

[0005] A quorum device is used to break a tie when a storage system fault occurs, when exactly half of the nodes that were previously a member of the system are present. A quorum device is also used to store a backup copy of important system configuration data.

[0006] It is possible for a system to split into two groups where each group contains half the original number of nodes in the system. A quorum device determines which group of nodes stops operating and processing I / O requests. In this tie-break situation, the first group of nodes that accesses the quorum device is marked as the owner of the quorum device and as a result continues to operate as the system, handling all I / O requests. If the other group of nodes cannot access the quorum device or finds that the quorum device is owned by another group of nodes, it stops operating as the system and does not handle I / O requests.

[0007] A quorum device is conventionally provided by means of utilizing the Internet Protocol network and a quorum application that can be deployed on a host in an independent failure domain. Alternatively, a quorum device is conventionally provided through the Fibre Channel network by utilizing a third controller acting as the independent domain with visibility across all sites in the cluster, so it can be accessed in failure scenarios. The quorum device is traditionally a dumb device where the system offloads some IO and configuration data. SUMMARY

[0008] According to an aspect of the present invention there is provided a computer-implemented method for managing a quorum device for a storage system having network of storage controllers of storage clusters, said method comprising: using a first storage controller as a volume-based quorum device for a second storage controller, wherein the first storage controller is aware of being treated as a quorum device; taking snapshots of cluster state metadata at known points and saving as quorum volumes; and recovering a storage cluster from the cluster state metadata in the event of a failure.

[0009] The method has the advantage of providing a quorum device at a storage controller and leveraging features of the storage controller such that the quorum device can take snapshots for recovery using cluster state metadata. This enables controlled point-in-time recovery for volumes.

[0010] According to another aspect of the present invention there is provided system for managing a quorum device for a storage system having network of storage controllers of storage clusters, comprising: a processor and a memory configured to provide computer program instructions to the processor to execute a method of: using a first storage controller as a volume-based quorum device for a second storage controller, wherein the first storage controller is aware of being treated as a quorum device; taking snapshots of cluster state metadata at known points and saving as quorum volumes; and recovering a storage cluster from the cluster state metadata in the event of a failure.

[0011] According to a further aspect of the present invention there is provided computer program product for managing a quorum device for a storage system having network of storage controllers of storage clusters, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to: use a first storage controller as a volume-based quorum device for a second storage controller, wherein the first storage controller is aware of being treated as a quorum device; take snapshots of cluster state metadata at known points and saving as quorum volumes; and recover a storage cluster from the cluster state metadata in the event of a failure.

[0012] The computer readable storage medium may be a non-transitory computer readable storage medium and the computer readable program code may be executable by a processing circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings: Figures 1A and 1B are block diagrams of example embodiments of storage systems in which embodiments of the present invention may be implemented; Figure 2 is a flow diagram of an example embodiment of a method in accordance with embodiments of the present invention; Figure 3 is a block diagram illustrating an example embodiment of a storage system in accordance with embodiments of the present invention; Figures 4A to 4D are a series of schematic diagrams illustrating a recovery scenario using the described method; Figure 5 is a block diagram of an example embodiment of a computing system in accordance with embodiments of the present invention; and Figure 6 is a block diagram of an example embodiment of a computing environment for the execution of at least some of the computer code involved in performing the present invention.

[0014] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numbers may be repeated among the figures to indicate corresponding or analogous features. DETAILED DESCRIPTION

[0015] Embodiments of a method, system, and computer program product are provided managing quorum devices for a storage system having network of storage controllers of storage clusters. The method and system may be used for safeguarded quorum snapshotting by managing quorum devices for a network of storage controllers.

[0016] The method uses a first storage controller as a volume-based quorum device for a second storage controller. The term “volume-based" quorum device Is used to define a quorum device that provisions quorum volumes at a storage controller. The volume-based quorum devices may be used for provisioning volumes having only customer data. The first storage controller is aware of being treated as a quorum device and integrated storage-centric actions into a control flow of the quorum device.

[0017] The volume-based quorum device is configured to take snapshots of cluster state metadata at known points and saving the snapshots as quorum volumes, A storage cluster may then be recovered by using the cluster state metadata in the event of a failure, such as an insider attack or catastrophic error.

[0018] The described method and system focus on volume-based quorum devices for clusters of storage controllers and in particular provide configured storage controllers to host quorum devices and to safeguard and efficiently recover cluster configuration in quorum devices using safeguarded quorum snapshotting.

[0019] The method and system provide recovery of system metadata that is being checkpointed using a safeguarded snapshot on a quorum device, so that in the event of an attack or system misconfiguration that metadata can be recovered to a good state.

[0020] The managing of quorum devices in a storage system is an improvement in the technical field of computer storage generally and more particularly in the technical field of data recovery in security systems.

[0021] Referring to Figure 1 A, a block diagram shows an example embodiment of a storage system 100 in which the described method and system may be implemented. The example system includes one or more hosts 110 or clients that access a volume 135,145 provided by storage controllers 130,140 in a storage area network 120. The storage controllers 130,140 may provide clusters of multiple nodes 131,132,141,142. The volumes 135,145 are logical drives that provide a single accessible storage area for underlying physical storage networks 160 formed of multiple physical storage devices 161-163. Multiple storage controllers 130,140 are used for high availability configurations.

[0022] It is possible to have many technologies implementing the underlying volumes 135,145. As examples, some volumes 135, 145 may be implemented using deduplication, some may be implemented using flash-core drives, some may be implemented using conventional flash drives or nearline storage. This provides an asymmetry to the volumes 135,145.

[0023] Figure 1B illustrates the flexibility and high availability of configurations of storage systems 100. Multiple hosts 110 may carry out operations on multiple nodes 131,132,141,142 providing a host zone 170 using a storage area network (SAN) fabric 180. A storage system zone 190 is provided between the nodes 131,132, 141,142, and physical storage systems 161-163 connected using the storage area network fabric 180. The redundant SAN fabric comprises a fault-tolerant arrangement of two or more counterpart SANs that provide alternative paths for each SAN-attached device.

[0024] In conventional storage controllers, a quorum device provides two functions. Firstly, a tie-breaking capability when half of the nodes cannot see the other half. Secondly, to keep a copy of important cluster state that is used in a recovery scenario to rebuild system and recover data and configuration of the system. These two functions may be provided by the described volume-based quorum device with added functionality as described below.

[0025] Referring to Figure 2, a flow diagram shows an example embodiment of a computer-implemented method for managing quorum devices for a storage system having network of storage controllers of storage clusters.

[0026] The method uses 201 a first storage controller as a volume-based quorum device for a second storage controller and where the first storage controller is aware of being treated as a quorum device. The first storage controller may be a remote storage controller and the second storage controller may be a local storage controller or vice versa depending on the context.

[0027] The method may make the first storage controller aware that it is hosting a quorum device for another cluster by the second storage controller sending a message over the fabric to the first storage controller to make it aware that it is now using the first storage controller as its quorum device. The first storage controller may then tag the volume-based quorum device as being in-use, for example, by changing state from "free" / advertised to "in-use" / private.

[0028] The method may implement 202 automatic discovery and selection of a volume-based quorum device on the storage system. Storage systems are discoverable on the fabric and the Internet Protocol network and a quorum device may be automatically configured,

[0029] Advanced features of the first storage controller may be leveraged to allow the method to take snapshots / safeguarded copies of quorum state. The method may integrate 203 storage-centric actions into a control flow of the quorum device. The storage-centric actions may include one or more of the group of: volume snapshotting, safeguarded copies, and migration.

[0030] The method may provide 204 authentication requirements for the first storage controller used as the quorum device to meet the authentication requirements of the second storage controller. The method may leverage security features for operations relating to quorum device volumes where the operations could be potentially destructive. Such operations relating to the quorum-tagged volumes may leverage features such as two-person authentication where they could be potentially destructive.

[0031] The method may select 205 recovery points for taking snapshots depending on the type of cluster state metadata. A user may want to recover from a very latest snapshot of the recovery checkpoint for user volumes hence allowing access to the more up-to-date copy of volume data, while at the same time an older recovery point may be desired for system configuration.

[0032] The method may take 206 snapshots of cluster state metadata at known points and may save the snapshots as quorum volumes. The cluster state metadata may be metadata associated with cluster configuration and / or metadata associated with cluster volume contents.

[0033] The described method may also extend the concept of snapshot policies by integrating the concept of snapshot operations before performing significant configuration actions to preserve cluster state for recovery purposes. The method may leverage remotely hosted snapshots to allow recovery of the storage controller to different prior configuration states via a restore operation, for example, to recover from an insider attack.

[0034] Taking 206 snapshots of cluster state metadata includes taking snapshots by means of creating a safeguarded copy of a quorum volume through the implementation of a safeguarded policy. A safeguarded policy is configured to trigger safeguarded copies during significant configuration actions for quorum volumes, and for other data volumes in the event that these contain data associated with the quorum device cluster. A safeguarded policy may be configured to keep more than one backup copies of the quorum state allowing a finely grained point-in-time recovery checkpoint in case network of storage controllers was to suffer catastrophic failures.

[0035] The described method extends the use of safeguarded copies to backup configuration data which will allow the system to revert to a known good state after a security compromise. The method further lends itself in recovering the system from unintended configuration failures by a trusted user of the system which may perform an action that was not intended.

[0036] The method may recover 207 the storage cluster from the cluster state metadata in the event of a failure. The method may dynamically provision 208 quorum volumes between the first and second storage controllers subject to failure rules. The method may transfer 209 quorum volumes to another cluster in the event that a quorum-providing cluster is due to be decommissioned.

[0037] Referring to Figure 3, a block diagram 300 shows an example embodiment of the described system. A multi-cluster storage system is shown. A first cluster 310 in the form of a storage controller and multiple nodes includes a quorum communication layer 311 for notifying configuration actions. A quorum-providing cluster 320 is shown in the form of a storage controller and multiple nodes. The quorum-providing cluster 320 includes a quorum volume 321 and quorum snapshots 322. The quorum-providing cluster 320 includes quorum snapshot policies 323 and quorum snapshot retention policies. The first cluster 310 is connected to the quorum providing cluster 320 via a network 340 and may be connected to other quorum devices 330.

[0038] Figures 4A to 4D show an example of a series of instances of managing a quorum device for a storage system in accordance with the described method using the first cluster 310 and quorum cluster 320 of Figure 3. In Figure 4A, a first cluster 310 configures 401 a quorum cluster 320 and aquorum volume 411 is empty. In Figure 4B, a quorum snapshot A (empty) 421 is taken before an update command 402 from the first cluster 310 notifies the quorum cluster 320 of configuration actions. The first cluster 310 issues a command 402 to create a new storage pool (for example, "mkmdiskgrp” command) and updates the quorum volume 411 to "mdiskgrpO".

[0039] Figure 4C shows a second quorum snapshot B (mdiskgrpO) 422 taken before a new update command as the first cluster 310 again notifies the quorum cluster 320 of configuration actions. A hostile actor via the first cluster 310 runs a hostile command 403 to the quorum cluster 320 to delete a specified storage pool (for example, ''rmmdiskgrp” command) and the quorum volume 411 is emptied.

[0040] Figure 4D shows that as part of the recovery, the quorum snapshot B (mdiskgrpO) 422 taken before the hostile command 403 is used to restore the cluster hardened state to a good state. The quorum volume 411 is recovered to “mdiskgrpO’ from quorum snapshot B 422.

[0041] The described method and system create a volume-based quorum device to act as a tiebreaker as well as to store metadata of the local system onto a remote system. In doing so, a quorum device is created that can be snapshotted by means of creating a safeguarded copy of the volume through the implementation of a safeguarded policy. The concept of safeguarded copy policies may be extended to trigger safeguarded copies during significant configuration actions for these quorum volumes, and potentially for other data volumes in the event that these contain data associated with the remote cluster. The policy may be configured to keep more than one backup copies of the quorum state hence allowing a finely grained point-in-time recovery checkpoint in case the system was to suffer catastrophic failures induced by an insider attack.

[0042] A safeguarded copy of a volume cannot be tampered with and can only be removed when its expiration conditions have been met. A safeguarded copy allows a secure mechanism for data recovery; however, conventionally, it is only restricted to volumes which have user data. The described method and system extend the use of safeguarded copies to backup configuration data which allows the storage system to revert to a known good state after a security compromise. The method and system further lend in recovering the system from unintended configuration failures by a trusted user of the system which may perform an action that was not intended.

[0043] The state that will be snapshotted on the volume-based quorum device can be categorized into two main classes. Firstly, metadata associated to system configuration e.g., users, user groups, Network Time Protocol / Domain Name Service (NTP / DNS) server objects etc. Secondly, metadata associated with a logical volume (vdisk) content e.g., volume extents / grain etc. This will allow flexibility in selecting a recovery point depending on the type of metadata in question. For example, a user may want to recover from a very latest snapshot of the recovery checkpoint for user volumes hence allowing access to the more up-to-date copy of logical volume data, while at the same time an older recovery point might be desired for system configuration.

[0044] The volume-based quorum device removes the need for a dedicated mediation service (as is needed in the existing IP quorum service) in a cloud configuration where several storage controllers may already have visibility of each other on the network. In the described method, storage controllers may dynamically provision quorum volumes from one another, subject to failure domain rules. Quorum volumes may be transferred to other clusters in the event that quorum-providing clusters are due to be decommissioned, for example, through 'migrate' functionality.

[0045] The quorum providing cluster may have distinct authentication requirements to ensure that users cannot interact with the quorum cluster using the same credentials as the base cluster, and that operations relating to the quorum-tagged volumes leverage features such as two-person authentication where they could be potentially destructive.

[0046] By configuring a regular storage system as a quorum device, many features that a remote storage system has may be exploited, for example, volume migration, snapshots, safeguarded copy. When applied to a quorum device, system metadata can be recovered from a good point-in-time copy after a security incident which cuts down on the recovery time. By making use of a network connected storage system for mediation as a volumebased quorum device, a separate quorum device such as a conventional IP quorum device is not required.

[0047] The described method and system have advantage over conventional methods that configure multiple independent devices in different failure domains which can be costly both in terms of system resources as well as maintenance overheads. Storage controllers usually are designed for high availability whereas conventional IP quorum devices are not typically sophisticated.

[0048] Figure 5 shows a block diagram of a computing system 500 at which the described system may be implemented. The computing system 500 may include at least one processor 501, a hardware module, or a circuit for executing the functions of the described components which may be software units executing on the at least one processor. Multiple processors running parallel processing threads may be provided enabling parallel processing of some or all of the functions of the components. Memory 502 may be configured to provide computer instructions 503 to the at least one processor 501 to carry out the functionality of the components.

[0049] A storage controller 520 of a storage system may be provided on the computing system 500 and may include a volume-based quorum system 520 for managing a quorum device for a storage system having network of storage controllers of storage clusters. The volume-based quorum system 520 may include the following components.

[0050] A quorum communication layer component 521 may be provided on all storage controllers in a storage network to communicate with a volume-based quorum device on another storage controller. A quorum device discovery component 522 may be provided for implementing automatic discovery and selection of a volumebased quorum device on the storage system.

[0051] A volume-based quorum device setting component 531 may be provided for using the storage controller 520 as a volume-based quorum device for a second storage controller. An awareness component 532 may be provided for making the storage controller aware of being treated as a quorum device.

[0052] A storage controller integration component 533 may be provided for leveraging features of the remote storage controller and integrating storage-centric actions into a control flow of the quorum device, wherein the storage-centric actions include one or more of the group of: volume snapshotting, safeguarded copies, and migration.

[0053] An authentication component 534 may be provided for providing authentication requirements for the first storage controller used as the quorum device to meet the authentication requirements of the second storage controller.

[0054] A quorum volume provisioning component 535 may be provided for dynamically provisioning quorum volumes between the first and second storage controllers, subject to failure rules. A quorum transferring component 536 may be provided for transferring quorum volumes to another cluster in the event that a quorumproviding cluster is due to be decommissioned.

[0055] A snapshot taking component 541 may be provided for taking snapshots of cluster state metadata at known points and saving as quorum volumes.

[0056] A snapshot recovery point selecting component 542 may be provided for selecting recovery points for taking snapshots depending on the type of cluster state metadata. For example, the cluster state metadata may be metadata associated with cluster configuration and / or metadata associated with cluster volume contents.

[0057] A quorum snapshot policy component 543 may be provided for providing a policy for taking snapshots of cluster state metadata including taking snapshots by means of creating a safeguarded copy of a quorum volume through the implementation of a safeguarded policy. A quorum snapshot retention component 544 may be provided for providing a policy on the retention of the snapshots.

[0058] A recovery component 545 may be provided for recovering a storage cluster from the cluster state metadata in the event of a failure.

[0059] Various aspects of the present disclosure are described by narrative text, flowcharts, block diagrams of computer systems and / or block diagrams of the machine logic included in computer program product (CPP) embodiments. With respect to any flowcharts, depending upon the technology involved, the operations can be performed in a different order than what is shown in a given flowchart. For example, again depending upon the technology involved, two operations shown in successive flowchart blocks may be performed in reverse order, as a single integrated step, concurrently, or in a manner at least partially overlapping in time.

[0060] A computer program product embodiment ("CPP embodiment" or “CPP”) is a term used in the present disclosure to describe any set of one, or more, storage media (also called "mediums") collectively included in a set of one, or more, storage devices that collectively include machine readable code corresponding to instructions and / or data for performing computer operations specified in a given CPP claim. A "storage device" is any tangible device that can retain and store instructions for use by a computer processor. Without limitation, the computer readable storage medium may be an electronic storage medium, a magnetic storage medium, an optical storage medium, an electromagnetic storage medium, a semiconductor storage medium, a mechanical storage medium, or any suitable combination of the foregoing. Some known types of storage devices that include these mediums include: diskette, hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), static random access memory (SRAM), compact disc read-only memory (CD-ROM), digital versatile disk (DVD), memory stick, floppy disk, mechanically encoded device (such as punch cards or pits I lands formed in a major surface of a disc) or any suitable combination of the foregoing. A computer readable storage medium, as that term is used in the present disclosure, is not to be construed as storage in the form of transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide, light pulses passing through a fiber optic cable, electrical signals communicated through a wire, and / or other transmission media. As will be understood by those of skill in the art, data is typically moved at some occasional points in time during normal operations of a storage device, such as during access, de-fragmentation or garbage collection, but this does not render the storage device as transitory because the data is not transitory while it is stored.

[0061] Referring to FIG. 6, computing environment 600 contains an example of an environment for the execution of at least some of the computer code involved in performing the inventive methods, such as volumebased quorum system code 650. In addition to block 650, computing environment 600 includes, for example, computer 601, wide area network (WAN) 602, end user device (EUD) 603, remote server 604, public cloud 605, and private cloud 606. In this embodiment, computer 601 includes processor set 610 (including processing circuitry 620 and cache 621), communication fabric 611, volatile memory 612, persistent storage 613 (including operating system 622 and block 650, as identified above), peripheral device set 614 (including user interface (UI) device set 623, storage 624, and Internet of Things (loT) sensor set 625), and network module 615. Remote server 604 includes remote database 630. Public cloud 605 includes gateway 640, cloud orchestration module 641, host physical machine set 642, virtual machine set 643, and container set 644.

[0062] COMPUTER 601 may taka the form of a desktop computer, laptop computer, tablet computer, smart phone, smart watch or other wearable computer, mainframe computer, quantum computer or any other form of computer or mobile device now known or to be developed in the future that is capable of running a program, accessing a network or querying a database, such as remote database 630. As is well understood in the art of computer technology, and depending upon the technology, performance of a computer-implemented method may be distributed among multiple computers and / or between multiple locations. On the other hand, in this presentation of computing environment 600, detailed discussion is focused on a single computer, specifically computer 601, to keep the presentation as simple as possible. Computer 601 may be located in a cloud, even though it is not shown in a cloud in Figure 6. On the other hand, computer 601 is not required to be in a cloud except to any extent as may be affirmatively indicated.

[0063] PROCESSOR SET 610 includes one, or more, computer processors of any type now known or to be developed in the future. Processing circuitry 620 may be distributed over multiple packages, for example, multiple, coordinated integrated circuit chips. Processing circuitry 620 may implement multiple processor threads and / or multiple processor cores. Cache 621 is memory that is located in the processor chip package(s) and is typically used for data or code that should be available for rapid access by the threads or cores running on processor set 610. Cache memories are typically organized into multiple levels depending upon relative proximity to the processing circuitry. Alternatively, some, or all, of the cache for the processor set may be located “off chip." In some computing environments, processor set 610 may be designed for working with qubits and performing quantum computing.

[0064] Computer readable program instructions are typically loaded onto computer 601 to cause a series of operational steps to be performed by processor set 610 of computer 601 and thereby effect a computer-implemented method, such that the instructions thus executed will instantiate the methods specified in flowcharts and / or narrative descriptions of computer-implemented methods included in this document (collectively referred to as “the inventive methods”). These computer readable program instructions are stored in various types of computer readable storage media, such as cache 621 and the other storage media discussed below. The program instructions, and associated data, are accessed by processor set 610 to control and direct performance of the inventive methods. In computing environment 600, at least some of the instructions for performing the inventive methods may be stored In block 650 in persistent storage 613.

[0065] COMMUNICATION FABRIC 611 is the signal conduction path that allows the various components of computer 601 to communicate with each other. Typically, this fabric is made of switches and electrically conductive paths, such as the switches and electrically conductive paths that make up busses, bridges, physical input / output ports and the like. Other types of signal communication paths may be used, such as fiber optic communication paths and / or wireless communication paths.

[0066] VOLATILE MEMORY 612 is any type of volatile memory now known or to be developed in the future. Examples include dynamic type random access memory (RAM) or static type RAM. Typically, volatile memory 612 is characterized by random access, but this is not required unless affirmatively indicated. In computer 601, the volatile memory 612 is located in a single package and is internal to computer 601, but, alternatively or additionally, the volatile memory may be distributed over multiple packages and / or located externally with respect to computer 601.

[0067] PERSISTENT STORAGE 613 is any form of non-volatile storage for computers that is now known or to be developed in the future. The non-volatility of this storage means that the stored data is maintained regardless of whether power is being supplied to computer 601 and / or directly to persistent storage 613. Persistent storage 613 may be a read only memory (ROM), but typically at least a portion of the persistent storage allows writing of data, deletion of data and re-writing of data. Some familiar forms of persistent storage include magnetic disks and solid state storage devices. Operating system 622 may take several forms, such as various known proprietary operating systems or open source Portable Operating System Interface-type operating systems that employ a kernel. The code included in block 650 typically includes at least some of the computer code involved in performing the inventive methods.

[0068] PERIPHERAL DEVICE SET 614 includes the set of peripheral devices of computer 601. Data communication connections between the peripheral devices and the other components of computer 601 may be implemented in various ways, such as Bluetooth connections, Near-Field Communication (NFC) connections, connections made by cables (such as universal serial bus (USB) type cables), insertion-type connections (for example, secure digital (SD) card), connections made through local area communication networks and even connections made through wide area networks such as the internet. In various embodiments, UI device set 623 may include components such as a display screen, speaker, microphone, wearable devices (such as goggles and smart watches), keyboard, mouse, printer, touchpad, game controllers, and haptic devices. Storage 624 is external storage, such as an external hard drive, or insertable storage, such as an SD card. Storage 624 may be persistent and / or volatile. In some embodiments, storage 624 may take the form of a quantum computing storage device for storing data in the form of qubits. In embodiments where computer 601 is required to have a large amount of storage (for example, where computer 601 locally stores and manages a large database) then this storage may be provided by peripheral storage devices designed for storing very large amounts of data, such as a storage area network (SAN) that is shared by multiple, geographically distributed computers. loT sensor set 625 is made up of sensors that can be used in Internet of Things applications. For example, one sensor may be a thermometer and another sensor may be a motion detector.

[0069] NETWORK MODULE 615 is the collection of computer software, hardware, and firmware that allows computer 601 to communicate with other computers through WAN 602. Network module 615 may include hardware, such as modems or Wi-Fi signal transceivers, software for packetizing and / or de-packetizing data for communication network transmission, and / or web browser software for communicating data over the internet. In some embodiments, network control functions and network forwarding functions of network module 615 are performed on the same physical hardware device. In other embodiments (for example, embodiments that utilize software-defined networking (SDN)), the control functions and the forwarding functions of network module 615 are performed on physically separate devices, such that the control functions manage several different network hardware devices. Computer readable program instructions for performing the inventive methods can typically be downloaded to computer 601 from an external computer or external storage device through a network adapter card or network interface included in network module 615.

[0070] WAN 602 is any wide area network (for example, the internet) capable of communicating computer data over non-local distances by any technology for communicating computer data, now known or to be developed in the future. In some embodiments, the WAN 602 may be replaced and / or supplemented by local area networks (LANs) designed to communicate data between devices located in a local area, such as a Wi-Fi network. The WAN and / or LANs typically include computer hardware such as copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and edge servers.

[0071] END USER DEVICE (EUD) 603 is any computer system that is used and controlled by an end user (for example, a customer of an enterprise that operates computer 601), and may take any of the forms discussed above in connection with computer 601. EUD 603 typically receives helpful and useful data from the operations of computer 601. For example, in a hypothetical case where computer 601 is designed to provide a recommendation to an end user, this recommendation would typically be communicated from network module 615 of computer 601 through WAN 602 to EUD 603. In this way, EUD 603 can display, or otherwise present, the recommendation to an end user. In some embodiments, EUD 603 may be a client device, such as thin client, heavy client, mainframe computer, desktop computer and so on.

[0072] REMOTE SERVER 604 is any computer system that serves at least some data and / or functionality to computer 601. Remote server 604 may be controlled and used by the same entity that operates computer 601. Remote server 604 represents the machine(s) that collect and store helpful and useful data for use by other computers, such as computer 601. For example, in a hypothetical case where computer 601 is designed and programmed to provide a recommendation based on historical data, then this historical data may be provided to computer 601 from remote database 630 of remote server 604.

[0073] PUBLIC CLOUD 605 is any computer system available for use by multiple entities that provides on-demand availability of computer system resources and / or other computer capabilities, especially data storage (cloud storage) and computing power, without direct active management by the user. Cloud computing typically leverages sharing of resources to achieve coherence and economies of scale. The direct and active management of the computing resources of public cloud 605 is performed by the computer hardware and / or software of cloud orchestration module 641. The computing resources provided by public cloud 605 are typically implemented by virtual computing environments that run on various computers making up the computers of host physical machine set 642, which is the universe of physical computers in and / or available to public cloud 605. The virtual computing environments (VCEs) typically take the form of virtual machines from virtual machine set 643 and / or containers from container set 644. It is understood that these VCEs may be stored as images and may be transferred among and between the various physical machine hosts, either as images or after instantiation of the VCE. Cloud orchestration module 641 manages the transfer and storage of images, deploys new instantiations of VCEs and manages active instantiations of VCE deployments. Gateway 640 is the collection of computer software, hardware, and firmware that allows public cloud 605 to communicate through WAN 602.

[0074] Some further explanation of virtualized computing environments (VCEs) will now be provided. VCEs can be stored as “images." A new active instance of the VCE can be instantiated from the image. Two familiar types of VCEs are virtual machines and containers. A container is a VCE that uses operating-system-level virtualization. This refers to an operating system feature in which the kernel allows the existence of multiple isolated user-space instances, called containers. These isolated user-space instances typically behave as real computers from the point of view of programs running in them. A computer program running on an ordinary operating system can utilize all resources of that computer, such as connected devices, files and folders, network shares, CPU power, and quantifiable hardware capabilities. However, programs running inside a container can only use the contents of the container and devices assigned to the container, a feature which is known as containerization,

[0075] PRIVATE CLOUD 606 is similar to public cloud 605, except that the computing resources are only available for use by a single enterprise. While private cloud 606 is depicted as being in communication with WAN 602, in other embodiments a private cloud may be disconnected from the internet entirely and only accessible through a local / private network. A hybrid cloud is a composition of multiple clouds of different types (for example, private, community or public cloud types), often respectively implemented by different vendors. Each of the multiple clouds remains a separate and discrete entity, but the larger hybrid cloud architecture is bound together by standardized or proprietary technology that enables orchestration, management, and / or data / application portability between the multiple constituent clouds. In this embodiment, public cloud 605 and private cloud 606 are both part of a larger hybrid cloud.

[0076] 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.

[0077] Improvements and modifications can be made to the foregoing without departing from the scope of the present invention.

Claims

1. A computer-implemented method for managing a quorum device for a storage system having network of storage controllers of storage clusters, said method comprising:using a first storage controller as a volume-based quorum device for a second storage controller, wherein the first storage controller is aware of being treated as a quorum device;taking snapshots of cluster state metadata at known points and saving as quorum volumes; and recovering a storage cluster from the cluster state metadata in the event of a failure.

2. The method of claim 1, wherein the cluster state metadata is metadata associated with cluster configuration and / or metadata associated with cluster volume contents and the method includes:selecting recovery points for taking snapshots depending on the type of cluster state metadata.

3. The method of claim 1 or claim 2, including:dynamically provisioning quorum volumes between the first and second storage controllers, subject to failure rules.

4. The method of any of claims 1 to 3, including:transferring quorum volumes to another cluster in the event that a quorum-providing cluster is due to be decommissioned.

5. The method of any of the preceding claims, including:providing authentication requirement for the first storage controller used as the quorum device to meet the authentication requirements of the second storage controller.

6. The method of any of the preceding claims, including:leveraging security features for operations relating to quorum device volumes where the operations could be potentially destructive.

7. The method of any of the preceding claims, Including:integrating storage-centric actions into a control flow of the quorum device, wherein the storage-centric actions include one or more of the group of: volume snapshotting, safeguarded copies, and migration.

8. The method of any of the preceding claims, wherein taking snapshots of cluster state metadata includes taking snapshots by means of creating a safeguarded copy of a quorum volume through the implementation of a safeguarded policy.

9. The method of claim 8, wherein a safeguarded policy is configured to trigger safeguarded copies during significant configuration actions for quorum volumes, and for other data volumes in the event that these contain data associated with the quorum device cluster.

10. The method of claim 8 or claim 9, wherein a safeguarded policy is configured to keep more than one backup copies of the quorum state allowing a finely grained point-in-time recovery checkpoint in case network of storage controllers was to suffer catastrophic failures.

11. The method of any of the preceding claims, including: implementing automatic discovery and selection of a volume-based quorum device on the storage system.

12. A system for managing a quorum device for a storage system having network of storage controllers of storage clusters, comprising:a processor and a memory configured to provide computer program instructions to the processor to execute a method of:using a first storage controller as a volume-based quorum device for a second storage controller, wherein the first storage controller is aware of being treated as a quorum device;taking snapshots of cluster state metadata at known points and saving as quorum volumes; and recovering a storage cluster from the cluster state metadata in the event of a failure.

13. The system of claim 12, wherein the cluster state metadata is metadata associated with cluster configuration and / or metadata associated with cluster volume contents; and the method includes:selecting recovery points for taking snapshots depending on the type ofcluster state metadata.

14. The system of claim 12 or claim 13, wherein the method includes:dynamically provisioning quorum volumes between the first and second storage controllers, subject to failure rules.

15. The system of any of claims 12 to 14, wherein the method includes:transferring quorum volumes to another cluster in the event that a quorum-providing cluster is due to be decommissioned.

16. The system of any of claims 12 to 15, wherein the method includes:providing authentication requirements for the first storage controller used as the quorum device to meet the authentication requirements of the second storage controller.

17. The system of any of claims 12 to 16, wherein the method includes:integrating storage-centric actions into a control flow of the quorum device, wherein the storage-centric actions include one or more of the group of: volume snapshotting, safeguarded copies, and migration.

18. The system of any of claims 12 to 17, wherein taking snapshots of cluster state metadata includes taking snapshots by means of creating a safeguarded copy of a quorum volume through the implementation of a safeguarded policy.

19. The system of any of claims 12 to 18, wherein the method includes: implementing automatic discovery and selection of a volume-based quorum device on the storage system.

20. A computer program stored on a computer readable medium and loadable into the internal memory of a digital computer, comprising software code portions, when said program is run on a computer, for performing the method steps of any of the claims 1 to 11.18

Images